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Globular cluster
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin globulus—a small sphere. A globular cluster is sometimes known more simply as a globular.
Globular clusters, which are found in the halo of a galaxy, contain considerably more stars and are much older than the less dense galactic, or open clusters, which are found in the disk. Globular clusters are fairly common; there are about 150[2] to 158[3] currently known globular clusters in the Milky Way, with perhaps 10 to 20 more still undiscovered.[4] Large galaxies can have more: Andromeda, for instance, may have as many as 500.[5] Some giant elliptical galaxies, particularly those at the centers of galaxy clusters, such as M87,[6] have as many as 13,000 globular clusters. These globular clusters orbit the galaxy at large radii of 40 kiloparsecs (approximately 131,000 light-years) or more.[7]
Every galaxy of sufficient mass in the Local Group has an associated group of globular clusters, and almost every large galaxy surveyed has been found to possess a system of globular clusters.[8] The Sagittarius Dwarf galaxy and the disputed Canis Major Dwarf galaxy appear to be in the process of donating their associated globular clusters (such as Palomar 12) to the Milky Way.[9] This demonstrates how many of this galaxy's globular clusters might have been acquired in the past.
Although it appears that globular clusters contain some of the first stars to be produced in the galaxy, their origins and their role in galactic evolution are still unclear. It does appear clear that globular clusters are significantly different from dwarf elliptical galaxies and were formed as part of the star formation of the parent galaxy rather than as a separate galaxy.[10] However, recent conjectures by astronomers suggest that globular clusters and dwarf spheroidals may not be clearly separate and distinct types of objects.[11]
Observation history 1
- Classification of globulars 1.1
- Formation 2
Composition 3
- Metallic content 3.1
- Exotic components 3.2
- Color-magnitude diagram 4
Morphology 5
- Radii 5.1
- Mass segregation, luminosity and core collapse 5.2
- N-body simulations 5.3
- Intermediate forms 5.4
- Tidal encounters 6
- Orbits 7
- Planets 8
- See also 9
References 10
- General resources 10.1
- Books 10.2
- 10.3 Review articles
- External links 11
Observation history
|Cluster name
|Discovered by
|Abraham Ihle
|ω Cen
|Edmond Halley
|Gottfried Kirch
|Edmond Halley
|Philippe Loys de Chéseaux
|Philippe Loys de Chéseaux
|Jean-Dominique Maraldi
|Jean-Dominique Maraldi
The first globular cluster discovered was M22 in 1665 by Abraham Ihle, a German amateur astronomer.[12] However, given the small aperture of early telescopes, individual stars within a globular cluster were not resolved until Charles Messier observed M4.[13] The first eight globular clusters discovered are shown in the table. Subsequently, Abbé Lacaille would list NGC 104, NGC 4833, M55, M69, and NGC 6397 in his 1751–52 catalogue. The M before a number refers to the catalogue of Charles Messier, while NGC is from the New General Catalogue by John Dreyer.
William Herschel began a survey program in 1782 using larger telescopes and was able to resolve the stars in all 33 of the known globular clusters. In addition he found 37 additional clusters. In Herschel's 1789 catalog of deep sky objects, his second such, he became the first to use the name globular cluster as their description.[13]
The number of globular clusters discovered continued to increase, reaching 83 in 1915, 93 in 1930 and 97 by 1947. A total of 152 globular clusters have now been discovered in the Milky Way galaxy, out of an estimated total of 180 ± 20.[4] These additional, undiscovered globular clusters are believed to be hidden behind the gas and dust of the Milky Way.
Beginning in 1914, Harlow Shapley began a series of studies of globular clusters, published in about 40 scientific papers. He examined the RR Lyrae variables in the clusters (which he assumed were cepheid variables) and would use their period–luminosity relationship for distance estimates. Later, it was found that RR Lyrae variables are fainter than cepheid variables, which caused Shapley to overestimate the distance to the clusters.[14]
Of the globular clusters within our Milky Way, the majority are found in the vicinity of the galactic core, and the large majority lie on the side of the celestial sky centered on the core. In 1918, this strongly asymmetrical distribution was used by Harlow Shapley to make a determination of the overall dimensions of the galaxy. By assuming a roughly spherical distribution of globular clusters around the galaxy's center, he used the positions of the clusters to estimate the position of the sun relative to the galactic center.[15] While his distance estimate was significantly in error, it did demonstrate that the dimensions of the galaxy were much greater than had been previously thought. His error was because dust in the Milky Way diminished the amount of light from a globular cluster that reached the earth, thus making it appear farther away. Shapley's estimate was, however, within the same order of magnitude as the currently accepted value.
Shapley's measurements also indicated that the Sun was relatively far from the center of the galaxy, contrary to what had previously been inferred from the apparently nearly even distribution of ordinary stars. In reality, ordinary stars lie within the galaxy's disk and are thus often obscured by gas and dust, whereas globular clusters lie outside the disk and can be seen at much further distances.
Classification of globulars
Shapley was subsequently assisted in his studies of clusters by Henrietta Swope and Helen Battles Sawyer (later Hogg). In 1927–29, Harlow Shapley and Helen Sawyer began categorizing clusters according to the degree of concentration the system has toward the core. The most concentrated clusters were identified as Class I, with successively diminishing concentrations ranging to Class XII. This became known as the Shapley–Sawyer Concentration Class. (It is sometimes given with numbers [Class 1–12] rather than Roman numerals.)[16]
At present, the formation of globular clusters remains a poorly understood phenomenon, and it remains uncertain whether the stars in a globular cluster form in a single generation, or are spawned across multiple generations over a period of several hundred million years. In many globular clusters, most of the stars are at approximately the same stage in stellar evolution, suggesting that they formed at about the same time.[18] However, the star formation history varies from cluster to cluster, with some clusters showing distinct populations of stars. An example of this is the globular clusters in the Large Magellanic Cloud (LMC) that exhibit a bimodal population. During their youth, these LMC clusters may have encountered giant molecular clouds that triggered a second round of star formation.[19] This star-forming period is relatively brief, compared to the age of many globular clusters.[20] It has also been proposed that the reason for this multiplicity in stellar populations could have a dynamical origin. In e.g. the Antennae galaxy we observe thanks to the Hubble Space Telescope clusters of clusters, regions in the galaxy that span hundreds of parsec, where many of the clusters will eventually collide and merge. Many of them present a significant range in ages, hence possibly metallicities, and their merger could plausibly lead to clusters with a bimodal or even multiple distribution of populations.[21]
Observations of globular clusters show that these stellar formations arise primarily in regions of efficient star formation, and where the interstellar medium is at a higher density than in normal star-forming regions. Globular cluster formation is prevalent in starburst regions and in interacting galaxies.[23] Research indicates a correlation between the mass of a central supermassive black holes (SMBH) and the extent of the globular cluster systems of elliptical and lenticular galaxies. The mass of the SMBH in such a galaxy is often close to the combined mass of the galaxy's globular clusters.[24]
No known globular clusters display active star formation, which is consistent with the view that globular clusters are typically the oldest objects in the Galaxy, and were among the first collections of stars to form. Very large regions of star formation known as super star clusters, such as Westerlund 1 in the Milky Way, may be the precursors of globular clusters.[25]
Globular clusters are generally composed of hundreds of thousands of low-metal, old stars. The type of stars found in a globular cluster are similar to those in the bulge of a spiral galaxy but confined to a volume of only a few million cubic parsecs. They are free of gas and dust and it is presumed that all of the gas and dust was long ago turned into stars.
Globular clusters can contain a high density of stars; on average about 0.4 stars per cubic parsec, increasing to 100 or 1000 stars per cubic parsec in the core of the cluster.[27] The typical distance between stars in a globular cluster is about 1 light year,[28] but at its core, the separation is comparable to the size of the Solar System (100 to 1000 times closer than stars near the Solar System).[29]
However, they are not thought to be favorable locations for the survival of planetary systems. Planetary orbits are dynamically unstable within the cores of dense clusters because of the perturbations of passing stars. A planet orbiting at 1 astronomical unit around a star that is within the core of a dense cluster such as 47 Tucanae would only survive on the order of 108 years.[30] There is a planetary system orbiting a pulsar (PSR B1620−26) that belongs to the globular cluster M4, but these planets likely formed after the event that created the pulsar.[31]
Some globular clusters, like Omega Centauri in our Milky Way and G1 in M31, are extraordinarily massive, with several million solar masses (M☉) and multiple stellar populations. Both can be regarded as evidence that supermassive globular clusters are in fact the cores of dwarf galaxies that are consumed by the larger galaxies.[32] About a quarter of the globular cluster population in the Milky Way may have been accreted along with their host dwarf galaxy.[33]
Several globular clusters (like M15) have extremely massive cores which may harbor black holes,[34] although simulations suggest that a less massive black hole or central concentration of neutron stars or massive white dwarfs explain observations equally well.
Metallic content
Globular clusters normally consist of Population II stars, which have a low proportion of elements other than hydrogen and helium when compared to Population I stars such as the Sun. Astronomers refer to these heavier elements as metals and to the proportions of these elements as the metallicity. These elements are produced by stellar nucleosynthesis and then are recycled into the interstellar medium, where they enter the next generation of stars. Hence the proportion of metals can be an indication of the age of a star, with older stars typically having a lower metallicity.[36]
The Dutch astronomer Pieter Oosterhoff noticed that there appear to be two populations of globular clusters, which became known as Oosterhoff groups. The second group has a slightly longer period of RR Lyrae variable stars.[37] Both groups have weak lines of metallic elements. But the lines in the stars of Oosterhoff type I (OoI) cluster are not quite as weak as those in type II (OoII).[37] Hence type I are referred to as "metal-rich" (e.g. Terzan 7[38]) while type II are "metal-poor" (e.g. ESO 280-SC06[39]).
These two populations have been observed in many galaxies, especially massive elliptical galaxies. Both groups are nearly as old as the universe itself and are of similar ages, but differ in their metal abundances. Many scenarios have been suggested to explain these subpopulations, including violent gas-rich galaxy mergers, the accretion of dwarf galaxies, and multiple phases of star formation in a single galaxy. In our Milky Way, the metal-poor clusters are associated with the halo and the metal-rich clusters with the bulge.[40]
In the Milky Way it has been discovered that the large majority of the low metallicity clusters are aligned along a plane in the outer part of the galaxy's halo. This result argues in favor of the view that type II clusters in the galaxy were captured from a satellite galaxy, rather than being the oldest members of the Milky Way's globular cluster system as had been previously thought. The difference between the two cluster types would then be explained by a time delay between when the two galaxies formed their cluster systems.[41]
Exotic components
Globular clusters have a very high star density, and therefore close interactions and near-collisions of stars occur relatively often. Due to these chance encounters, some exotic classes of stars, such as blue stragglers, millisecond pulsars and low-mass X-ray binaries, are much more common in globular clusters. A blue straggler is formed from the merger of two stars, possibly as a result of an encounter with a binary system.[42] The resulting star has a higher temperature than comparable stars in the cluster with the same luminosity, and thus differs from the main sequence stars formed at the beginning of the cluster.[43]
Astronomers have searched for black holes within globular clusters since the 1970s. The resolution requirements for this task, however, are exacting, and it is only with the Hubble space telescope that the first confirmed discoveries have been made. In independent programs, a 4,000 M☉ intermediate-mass black hole has been suggested to exist based on HST observations in the globular cluster M15 and a 20,000 M☉ black hole in the Mayall II cluster in the Andromeda Galaxy.[44] Both x-ray and radio emissions from Mayall II appear to be consistent with an intermediate-mass black hole.[45]
These are of particular interest because they are the first black holes discovered that were intermediate in mass between the conventional stellar-mass black hole and the supermassive black holes discovered at the cores of galaxies. The mass of these intermediate mass black holes is proportional to the mass of the clusters, following a pattern previously discovered between supermassive black holes and their surrounding galaxies.
Claims of intermediate mass black holes have been met with some skepticism. The heaviest objects in globular clusters are expected to migrate to the cluster center due to mass segregation. As pointed out in two papers by Holger Baumgardt and collaborators, the mass-to-light ratio should rise sharply towards the center of the cluster, even without a black hole, in both M15[46] and Mayall II.[47]
Color-magnitude diagram
The Hertzsprung-Russell diagram (HR-diagram) is a graph of a large sample of stars that plots their visual absolute magnitude against their color index. The color index, B−V, is the difference between the magnitude of the star in blue light, or B, and the magnitude in visual light (green-yellow), or V. Large positive values indicate a red star with a cool surface temperature, while negative values imply a blue star with a hotter surface.
When the stars near the Sun are plotted on an HR diagram, it displays a distribution of stars of various masses, ages, and compositions. Many of the stars lie relatively close to a sloping curve with increasing absolute magnitude as the stars are hotter, known as main-sequence stars. However the diagram also typically includes stars that are in later stages of their evolution and have wandered away from this main-sequence curve.
As all the stars of a globular cluster are at approximately the same distance from us, their absolute magnitudes differ from their visual magnitude by about the same amount. The main-sequence stars in the globular cluster will fall along a line that is believed to be comparable to similar stars in the solar neighborhood. The accuracy of this assumption is confirmed by comparable results obtained by comparing the magnitudes of nearby short-period variables, such as RR Lyrae stars and cepheid variables, with those in the cluster.[49]
By matching up these curves on the HR diagram the absolute magnitude of main-sequence stars in the cluster can also be determined. This in turn provides a distance estimate to the cluster, based on the visual magnitude of the stars. The difference between the relative and absolute magnitude, the distance modulus, yields this estimate of the distance.[50]
When the stars of a particular globular cluster are plotted on an HR diagram, in many cases nearly all of the stars fall upon a relatively well defined curve. This differs from the HR diagram of stars near the Sun, which lumps together stars of differing ages and origins. The shape of the curve for a globular cluster is characteristic of a grouping of stars that were formed at approximately the same time and from the same materials, differing only in their initial mass. As the position of each star in the HR diagram varies with age, the shape of the curve for a globular cluster can be used to measure the overall age of the star population.[51]
The most massive main-sequence stars will also have the highest absolute magnitude, and these will be the first to evolve into the giant star stage. As the cluster ages, stars of successively lower masses will also enter the giant star stage. Thus the age of a single population cluster can be measured by looking for the stars that are just beginning to enter the giant star stage. This forms a "knee" in the HR diagram, bending to the upper right from the main-sequence line. The absolute magnitude at this bend is directly a function of the age of globular cluster, so an age scale can be plotted on an axis parallel to the magnitude.
In addition, globular clusters can be dated by looking at the temperatures of the coolest white dwarfs. Typical results for globular clusters are that they may be as old as 12.7 billion years.[52] This is in contrast to open clusters which are only tens of millions of years old.
The ages of globular clusters place a bound on the age limit of the entire universe. This lower limit has been a significant constraint in cosmology. Historically, astronomers were faced with age estimates of globular clusters that appeared older than cosmological models would allow. However, better measurements of cosmological parameters through deep sky surveys and satellites such as the Hubble Space Telescope appear to have resolved this issue.[53]
Evolutionary studies of globular clusters can also be used to determine changes due to the starting composition of the gas and dust that formed the cluster. That is, the evolutionary tracks change with changes in the abundance of heavy elements. The data obtained from studies of globular clusters are then used to study the evolution of the Milky Way as a whole.[54]
In globular clusters a few stars known as blue stragglers are observed, apparently continuing the main sequence in the direction of brighter, bluer stars. The origins of these stars is still unclear, but most models suggest that these stars are the result of mass transfer in multiple star systems.[55]
In contrast to open clusters, most globular clusters remain gravitationally bound for time periods comparable to the life spans of the majority of their stars. However, a possible exception is when strong tidal interactions with other large masses result in the dispersal of the stars.
After they are formed, the stars in the globular cluster begin to interact gravitationally with each other. As a result the velocity vectors of the stars are steadily modified, and the stars lose any history of their original velocity. The characteristic interval for this to occur is the relaxation time. This is related to the characteristic length of time a star needs to cross the cluster as well as the number of stellar masses in the system.[57] The value of the relaxation time varies by cluster, but the mean value is on the order of 109 years.
|Milky Way
Although globular clusters generally appear spherical in form, ellipticities can occur due to tidal interactions. Clusters within the Milky Way and the Andromeda Galaxy are typically oblate spheroids in shape, while those in the Large Magellanic Cloud are more elliptical.[59]
Astronomers characterize the morphology of a globular cluster by means of standard radii. These are the core radius (rc), the half-light radius (rh), and the tidal radius (rt). The overall luminosity of the cluster steadily decreases with distance from the core, and the core radius is the distance at which the apparent surface luminosity has dropped by half.[60] A comparable quantity is the half-light radius, or the distance from the core within which half the total luminosity from the cluster is received. This is typically larger than the core radius.
Note that the half-light radius includes stars in the outer part of the cluster that happen to lie along the line of sight, so theorists will also use the half-mass radius (rm)—the radius from the core that contains half the total mass of the cluster. When the half-mass radius of a cluster is small relative to the overall size, it has a dense core. An example of this is Messier 3 (M3), which has an overall visible dimension of about 18 arc minutes, but a half-mass radius of only 1.12 arc minutes.[61]
Almost all globular clusters have a half-light radius of less than 10 pc, although there are well-established globular clusters with very large radii (i.e. NGC 2419 (Rh = 18 pc) and Palomar 14 (Rh = 25 pc)).[11]
Finally the tidal radius, or Roche limit, is the distance from the center of the globular cluster at which the external gravitation of the galaxy has more influence over the stars in the cluster than does the cluster itself. This is the distance at which the individual stars belonging to a cluster can be separated away by the galaxy. The tidal radius of M3 is about 40 arc minutes,[62] or about 113 pc[63] at the distance of 10.4 kpc.
Mass segregation, luminosity and core collapse
In measuring the luminosity curve of a given globular cluster as a function of distance from the core, most clusters in the Milky Way increase steadily in luminosity as this distance decreases, up to a certain distance from the core, then the luminosity levels off. Typically this distance is about 1–2 parsecs from the core. However about 20% of the globular clusters have undergone a process termed "core collapse". In this type of cluster, the luminosity continues to increase steadily all the way to the core region.[64] An example of a core-collapsed globular is M15.
Core-collapse is thought to occur when the more massive stars in a globular cluster encounter their less massive companions. Over time, dynamic processes cause individual stars to migrate from the center of the cluster to the outside. This results in a net loss of kinetic energy from the core region, leading the remaining stars grouped in the core region to occupy a more compact volume. When this gravothermal instability occurs, the central region of the cluster becomes densely crowded with stars and the surface brightness of the cluster forms a power-law cusp.[65] (Note that a core collapse is not the only mechanism that can cause such a luminosity distribution; a massive black hole at the core can also result in a luminosity cusp.)[66] Over a lengthy period of time this leads to a concentration of massive stars near the core, a phenomenon called mass segregation.
The dynamical heating effect of binary star systems works to prevent an initial core collapse of the cluster. When a star passes near a binary system, the orbit of the latter pair tends to contract, releasing energy. Only after the primordial supply of binaries is exhausted due to interactions can a deeper core collapse proceed.[67][68] In contrast, the effect of tidal shocks as a globular cluster repeatedly passes through the plane of a spiral galaxy tends to significantly accelerate core collapse.[69]
The different stages of core-collapse may be divided into three phases. During a globular cluster's adolescence, the process of core-collapse begins with stars near the core. However, the interactions between binary star systems prevents further collapse as the cluster approaches middle age. Finally, the central binaries are either disrupted or ejected, resulting in a tighter concentration at the core.
The interaction of stars in the collapsed core region causes tight binary systems to form. As other stars interact with these tight binaries, they increase the energy at the core, which causes the cluster to re-expand. As the mean time for a core collapse is typically less than the age of the galaxy, many of a galaxy's globular clusters may have passed through a core collapse stage, then re-expanded.[70]
The Hubble Space Telescope has been used to provide convincing observational evidence of this stellar mass-sorting process in globular clusters. Heavier stars slow down and crowd at the cluster's core, while lighter stars pick up speed and tend to spend more time at the cluster's periphery. The globular star cluster 47 Tucanae, which is made up of about 1 million stars, is one of the densest globular clusters in the Southern Hemisphere. This cluster was subjected to an intensive photographic survey, which allowed astronomers to track the motion of its stars. Precise velocities were obtained for nearly 15,000 stars in this cluster.[71]
A 2008 study by John Fregeau of 13 globular clusters in the Milky Way shows that three of them have an unusually large number of X-ray sources, or X-ray binaries, suggesting the clusters are middle-aged. Previously, these globular clusters had been classified as being in old age because they had very tight concentrations of stars in their centers, another test of age used by astronomers. The implication is that most globular clusters, including the other ten studied by Fregeau, are not in middle age as previously thought, but are actually in 'adolescence'.[72]
The overall luminosities of the globular clusters within the Milky Way and the Andromeda Galaxy can be modeled by means of a gaussian curve. This gaussian can be represented by means of an average magnitude Mv and a variance σ2. This distribution of globular cluster luminosities is called the Globular Cluster Luminosity Function (GCLF). (For the Milky Way, Mv = −7.20 ± 0.13, σ = 1.1 ± 0.1 magnitudes.)[73] The GCLF has also been used as a "standard candle" for measuring the distance to other galaxies, under the assumption that the globular clusters in remote galaxies follow the same principles as they do in the Milky Way.
N-body simulations
Computing the interactions between the stars within a globular cluster requires solving what is termed the N-body problem. That is, each of the stars within the cluster continually interacts with the other N−1 stars, where N is the total number of stars in the cluster. The naive CPU computational "cost" for a dynamic simulation increases in proportion to N3,[74][75] so the potential computing requirements to accurately simulate such a cluster can be enormous.[76] An efficient method of mathematically simulating the N-body dynamics of a globular cluster is done by subdividing into small volumes and velocity ranges, and using probabilities to describe the locations of the stars. The motions are then described by means of a formula called the Fokker-Planck equation. This can be solved by a simplified form of the equation, or by running Monte Carlo simulations and using random values. However the simulation becomes more difficult when the effects of binaries and the interaction with external gravitation forces (such as from the Milky Way galaxy) must also be included.[77]
The results of N-body simulations have shown that the stars can follow unusual paths through the cluster, often forming loops and often falling more directly toward the core than would a single star orbiting a central mass. In addition, due to interactions with other stars that result in an increase in velocity, some of the stars gain sufficient energy to escape the cluster. Over long periods of time this will result in a dissipation of the cluster, a process termed evaporation.[78] The typical time scale for the evaporation of a globular cluster is 1010 years.[57] In 2010 it became possible to directly compute, star by star, N-body simulations of a globular cluster over the course of its lifetime.[79]
Binary stars form a significant portion of the total population of stellar systems, with up to half of all stars occurring in binary systems. Numerical simulations of globular clusters have demonstrated that binaries can hinder and even reverse the process of core collapse in globular clusters. When a star in a cluster has a gravitational encounter with a binary system, a possible result is that the binary becomes more tightly bound and kinetic energy is added to the solitary star. When the massive stars in the cluster are sped up by this process, it reduces the contraction at the core and limits core collapse.[43]
The ultimate fate of a globular cluster must be either to accrete stars at its core, causing its steady contraction,[80] or gradual shedding of stars from its outer layers.[81]
Intermediate forms
The distinction between cluster types is not always clear-cut, and objects have been found that blur the lines between the categories. For example, BH 176 in the southern part of the Milky Way has properties of both an open and a globular cluster.[83]
In 2005, astronomers discovered a completely new type of star cluster in the Andromeda Galaxy, which is, in several ways, very similar to globular clusters. The new-found clusters contain hundreds of thousands of stars, a similar number to that found in globular clusters. The clusters share other characteristics with globular clusters such as stellar populations and metallicity. What distinguishes them from the globular clusters is that they are much larger – several hundred light-years across – and hundreds of times less dense. The distances between the stars are, therefore, much greater within the newly discovered extended clusters. Parametrically, these clusters lie somewhere between a globular cluster and a dwarf spheroidal galaxy.[84]
How these clusters are formed is not yet known, but their formation might well be related to that of globular clusters. Why M31 has such clusters, while the Milky Way does not, is not yet known. It is also unknown if any other galaxy contains these types of clusters, but it would be very unlikely that M31 is the sole galaxy with extended clusters.[84]
Tidal encounters
When a globular cluster has a close encounter with a large mass, such as the core region of a galaxy, it undergoes a tidal interaction. The difference in the pull of gravity between the part of the cluster nearest the mass and the pull on the furthest part of the cluster results in a tidal force. A "tidal shock" occurs whenever the orbit of a cluster takes it through the plane of a galaxy.
As a result of a tidal shock, streams of stars can be pulled away from the cluster halo, leaving only the core part of the cluster. These tidal interaction effects create tails of stars that can extend up to several degrees of arc away from the cluster.[85] These tails typically both precede and follow the cluster along its orbit. The tails can accumulate significant portions of the original mass of the cluster, and can form clumplike features.[86]
The globular cluster Palomar 5, for example, is near the apogalactic point of its orbit after passing through the Milky Way. Streams of stars extend outward toward the front and rear of the orbital path of this cluster, stretching out to distances of 13,000 light-years.[87] Tidal interactions have stripped away much of the mass from Palomar 5, and further interactions as it passes through the galactic core are expected to transform it into a long stream of stars orbiting the Milky Way halo.
Tidal interactions add kinetic energy into a globular cluster, dramatically increasing the evaporation rate and shrinking the size of the cluster.[57] Not only does tidal shock strip off the outer stars from a globular cluster, but the increased evaporation accelerates the process of core collapse. The same physical mechanism may be at work in Dwarf spheroidal galaxies such as the Sagittarius Dwarf, which appears to be undergoing tidal disruption due to its proximity to the Milky Way.
There are many globular clusters with a retrograde orbit round the Milky Way Galaxy.[88] A hypervelocity globular cluster was discovered around Messier 87 in 2014, having a velocity in excess of the escape velocity of M87.[89]
In 2000, the results of a search for giant planets in the globular cluster 47 Tucanae were announced. The lack of any successful discoveries suggests that the abundance of elements (other than hydrogen or helium) necessary to build these planets may need to be at least 40% of the abundance in the Sun. Terrestrial planets are built from heavier elements such as silicon, iron and magnesium. The very low abundance of these elements in globular clusters means that the member stars have a far lower likelihood of hosting Earth-mass planets, when compared to stars in the neighborhood of the Sun. Hence the halo region of the Milky Way galaxy, including globular cluster members, are unlikely to host habitable terrestrial planets.[90]
In spite of the lower likelihood of giant planet formation, just such an object has been found in the globular cluster Messier 4. This planet was detected orbiting a pulsar in the binary star system PSR B1620-26. The eccentric and highly inclined orbit of the planet suggests it may have been formed around another star in the cluster, then was later "exchanged" into its current arrangement.[91] The likelihood of close encounters between stars in a globular cluster can disrupt planetary systems, some of which break loose to become free floating planets. Even close orbiting planets can become disrupted, potentially leading to orbital decay and an increase in orbital eccentricity and tidal effects.[92]
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- ^ Chaboyer, B. "Globular Cluster Age Dating". Astrophysical Ages and Times Scales, ASP Conference Series 245: 162–172.
- ^ Piotto, Giampaolo (June 2009). "Observations of multiple populations in star clusters". The Ages of Stars, Proceedings of the International Astronomical Union, IAU Symposium 258: 233–244.
- ^ Weaver, D.; Villard, R.; Christensen, L. L.; Piotto, G.; Bedin, L. (2007-05-02). "Hubble Finds Multiple Stellar 'Baby Booms' in a Globular Cluster". Hubble News Desk. Retrieved 2007-05-01.
- ^ Amaro-Seoane, P.; Konstantinidis, S.; Brem, P.; Catelan, M. (2013). "Mergers of multimetallic globular clusters: the role of dynamics".
- ^ "This Star Cluster Is Not What It Seems". www.eso.org. European Southern Observatory. Retrieved 12 September 2014.
- ^ Elmegreen, B. G.; Efremov, Y. N. (1999). "A Universal Formation Mechanism for Open and Globular Clusters in Turbulent Gas". Astrophysical Journal 480 (2): 235.
- ^ Burkert, Andreas; Tremaine, Scott (April 1, 2010). "A correlation between central supermassive black holes and the globular cluster systems of early-type galaxies". arXiv:1004.0137 [astro-ph.CO]. "A possible explanation is that both large black-hole masses and large globular cluster populations are associated with recent major mergers.".
- ^ "Young and Exotic Stellar Zoo: ESO's Telescopes Uncover Super Star Cluster in the Milky Way". ESO. 2005-03-22. Retrieved 2007-03-20.
- ^ "ESA/Hubble Picture of the Week". Engulfed by Stars Near the Milky Way's Heart. Retrieved 28 June 2011.
- ^ Talpur, Jon (1997). "A Guide to Globular Clusters". Keele University. Retrieved 2007-04-25.
- ^ University of Durham - Department of Physics - The Hertzsprung-Russell Diagram of a Globular Cluster
- ^ ESO - eso0107 - Ashes from the Elder Brethren
- ^ Sigurdsson, Steinn (1992). "Planets in globular clusters?". Astrophysical Journal 399 (1): L95–L97.
- ^ Arzoumanian, Z.; Joshi, K.; Rasio, F. A.; Thorsett, S. E.; Joshi; Rasio; Thorsett (1999). "Orbital Parameters of the PSR B1620-26 Triple System". Proceedings of the 160th colloquium of the International Astronomical Union 105: 525.
- ^ Bekki, K.; Freeman, K. C. (December 2003). "Formation of ω Centauri from an ancient nucleated dwarf galaxy in the young Galactic disc". Monthly Notices of the Royal Astronomical Society 346 (2): L11–L15.
- ^ Forbes, Duncan A.; Bridges, Terry (January 25, 2010). "Accreted versus In Situ Milky Way Globular Clusters". arXiv:1001.4289 [astro-ph.GA].
- ^ van der Marel, Roeland (2002-03-03). "Black Holes in Globular Clusters". Space Telescope Science Institute. Retrieved 2006-06-08.
- ^ "Spot the Difference — Hubble spies another globular cluster, but with a secret". Picture of the Week. ESA/Hubble. Retrieved 5 October 2011.
- ^ Green, Simon F.; Jones, Mark H.; Burnell, S. Jocelyn (2004). An introduction to the sun and stars. Cambridge University Press. p. 240.
- ^ a b van Albada, T. S.; Baker, Norman (1973). "On the Two Oosterhoff Groups of Globular Clusters". Astrophysical Journal 185: 477–498.
- ^ Buonanno, R., Corsi, C.E., Pulone, L. (1995). "ESO 280-SC06". Astronomical Journal 109. Retrieved 2014-04-19.
- ^ "ESO 280-SC06". Globular cluster ESO 280-SC06, in Ara. Retrieved 2014-04-19.
- ^ Harris, W. E. (1976). "Spatial structure of the globular cluster system and the distance to the galactic center". Astronomical Journal 81: 1095–1116.
- ^ Lee, Y. W.; Yoon, S. J. (2002). "On the Construction of the Heavens". An Aligned Stream of Low-Metallicity Clusters in the Halo of the Milky Way 297 (5581): 578–81.
- ^ Leonard, P. J. t. (1989). "Stellar collisions in globular clusters and the blue straggler problem". The Astrophysical Journal 98: 217.
- ^ a b Rubin, V. C.; Ford, W. K. J. (1999). "A Thousand Blazing Suns: The Inner Life of Globular Clusters". Mercury 28: 26.
- ^ Savage, D.; Neal, N.; Villard, R.; Johnson, R.; Lebo, H. (2002-09-17). "Hubble Discovers Black Holes in Unexpected Places". HubbleSite (Space Telescope Science Institute). Retrieved 2006-05-25.
- ^ Finley, Dave (2007-05-28). "Star Cluster Holds Midweight Black Hole, VLA Indicates". NRAO. Retrieved 2007-05-29.
- ^ Baumgardt, Holger; Hut, Piet; Makino, Junichiro; McMillan, Steve; Portegies Zwart, Simon (2003). "On the Central Structure of M15". Astrophysical Journal Letters 582 (1): 21.
- ^ Baumgardt, Holger; Hut, Piet; Makino, Junichiro; McMillan, Steve; Portegies Zwart, Simon (2003). "A Dynamical Model for the Globular Cluster G1". Astrophysical Journal Letters 589 (1): 25.
- ^ "Cosmic fairy lights". ESA/Hubble Picture of the Week. Retrieved 29 April 2014.
- ^
- ^ Martin, Schwarzschild (1958). Structure and Evolution of Stars. Princeton University Press.
- ^
- ^ Hansen, B. M. S.; Brewer, J.; Fahlman, G. G.; Gibson, B. K.; Ibata, R.; Limongi, M.; Rich, R. M.; Richer, H. B.; Shara, M. M.; Stetson, P. B. (2002). "The White Dwarf Cooling Sequence of the Globular Cluster Messier 4". Astrophysical Journal Letters 574 (2): L155.
- ^ Majaess, D. (February 23, 2013). "Nearby Ancient Star is Almost as Old as the Universe". Universe Today. Retrieved November 29, 2014.
- ^ "Ashes from the Elder Brethren — UVES Observes Stellar Abundance Anomalies in Globular Clusters" (Press release). 2001-03-01. Retrieved 2006-05-26.
- ^ Leonard, Peter J. T. (1989). "Stellar collisions in globular clusters and the blue straggler problem". The Astronomical Journal 98: 217–226.
- ^ "Appearances can be deceptive". ESO Picture of the Week. Retrieved 12 February 2013.
- ^ a b c Benacquista, Matthew J. (2006). "Globular cluster structure". Living Reviews in Relativity. Retrieved 2006-08-14.
- ^ Staneva, A.; Spassova, N.; Golev, V. (1996). "The Ellipticities of Globular Clusters in the Andromeda Galaxy". Astronomy and Astrophysics Supplement 116 (3): 447–461.
- ^ Frenk, C. S.; White, S. D. M. (1980). "The ellipticities of Galactic and LMC globular clusters". Monthly Notices of the Royal Astronomical Society 286 (3): L39–L42.
- ^ Kenneth Janes (November 2000). "Star Clusters". Encyclopedia of Astronomy and Astrophysics. p. 2. Retrieved 26 March 2014.
- ^ Buonanno, R.; Corsi, C. E.; Buzzoni, A.; Cacciari, C.; Ferraro, F. R.; Fusi Pecci, F.; Corsi; Buzzoni; Cacciari; Ferraro; Fusi Pecci (1994). "The Stellar Population of the Globular Cluster M 3. I. Photographic Photometry of 10 000 Stars". Astronomy and Astrophysics 290: 69–103.
- ^ Da Costa, G. S.; Freeman, K. C. (May 1976). "The structure and mass function of the globular cluster M3". ApJ 206 (1): 128–137.
- ^ Brosche, P.; Odenkirchen, M.; Geffert, M. (March 1999). "Instantaneous and average tidal radii of globular clusters". New Astronomy 4 (2): 133–139.
- ^ Djorgovski, S.; King, I. R. (1986). "A preliminary survey of collapsed cores in globular clusters". Astrophysical Journal 305: L61–L65.
- ^ Ashman, Keith M.; Zepf, Stephen E. (1998). Globular cluster systems. Cambridge astrophysics series 30. Cambridge University Press. p. 29.
- ^ Binney, James; Merrifield, Michael (1998). Galactic astronomy. Princeton series in astrophysics. Princeton University Press. p. 371.
- ^ Vanbeveren, D. (2001). The influence of binaries on stellar population studies. Astrophysics and space science library 264. Springer. p. 397.
- ^ Spitzer, L., Jr. (June 2–4, 1986). P. Hut and S. McMillan, ed. "Dynamical Evolution of Globular Clusters". The Use of Supercomputers in Stellar Dynamics, Proceedings of a Workshop Held at the Institute for Advanced Study 267 (Princeton, USA: Springer-Verlag, Berlin Heidelberg New York): 3.
- ^ Gnedin, Oleg Y.; Lee, Hyung Mok; Ostriker, Jeremiah P. (September 1999). "Effects of Tidal Shocks on the Evolution of Globular Clusters". The Astrophysical Journal 522 (2): 935–949.
- ^ Bahcall, John N.; Piran, Tsvi; Weinberg, Steven (2004). Dark matter in the universe (2nd ed.). World Scientific. p. 51.
- ^ "Stellar Sorting in Globular Cluster 47". Hubble News Desk. 2006-10-04. Retrieved 2006-10-24.
- ^ Baldwin, Emily (2008-04-29). "Old globular clusters surprisingly young". Astronomy Now Online. Retrieved 2008-05-02.
- ^ Secker, Jeff (1992). "A Statistical Investigation into the Shape of the Globular cluster Luminosity Distribution". Astronomical Journal 104 (4): 1472–1481.
- ^ Benacquista, Matthew J. (2002-02-20). "Relativistic Binaries in Globular Clusters: 5.1 N-body". Living Reviews in Relativity. Retrieved 2006-10-25.
- ^
- ^ Heggie, D. C.; Giersz, M.; Spurzem, R.; Takahashi, K. (1998). Johannes Andersen, ed. "Dynamical Simulations: Methods and Comparisons". Highlights of Astronomy Vol. 11A, as presented at the Joint Discussion 14 of the XXIIIrd General Assembly of the IAU, 1997 (Kluwer Academic Publishers): 591.
- ^ Benacquista, Matthew J. (2006). "Relativistic Binaries in Globular Clusters". Living Reviews in Relativity 9.
- ^ J. Goodman and P. Hut, ed. (1985). Dynamics of Star Clusters (International Astronomical Union Symposia). Springer.
- ^ Hasani Zonoozi, Akram; et al. (March 2011). "Direct N-body simulations of globular clusters – I. Palomar 14". Monthly Notices of the Royal Astronomical Society 411 (3): 1989–2001.
- ^
- ^ Pooley, Dave. "Globular Cluster Dynamics: the importance of close binaries in a real N-body system". UW-Madison. Retrieved 2008-12-11.
- ^ "Globular Cluster M10". ESA/Hubble Picture of the Week. Retrieved 18 June 2012.
- ^ Ortolani, S.; Bica, E.; Barbuy, B.; Bica; Barbuy (1995). "BH 176 and AM-2: globular or open clusters?". Astronomy and Astrophysics 300: 726.
- ^ a b Huxor, A. P.; Tanvir, N. R.; Irwin, M. J.; R. Ibata (2005). "A new population of extended, luminous, star clusters in the halo of M31". Monthly Notices of the Royal Astronomical Society 360 (3): 993–1006.
- ^ Lauchner, A.; Wilhelm, R.; Beers, T. C.; Allende Prieto, C. (December 2003). "A Search for Kinematic Evidence of Tidal Tails in Globular Clusters". American Astronomical Society Meeting 203, #112.26.
- ^ Di Matteo, P.; Miocchi, P.; Capuzzo Dolcetta, R. (May 2004). "Formation and Evolution of Clumpy Tidal Tails in Globular Clusters". American Astronomical Society, DDA meeting #35, #03.03.
- ^ Staude, Jakob (2002-06-03). "Sky Survey Unveils Star Cluster Shredded By The Milky Way". Image of the Week. Sloan Digital Sky Survey. Retrieved 2006-06-02.
- ^ Kravtsov, V. V. (2001). "Globular Clusters and Dwarf Spheroidal Galaxies of the Outer Galactic Halo: on the Putative Scenario of their Formation" (PDF). Astronomical and Astrophysical Transactions 20 (1): 89–92.
- ^ Nelson Caldwell (CfA), Jay Strader (Michigan St), Aaron J. Romanowsky (San Jose St/Santa Cruz), Jean P. Brodie (Santa Cruz), Ben Moore (Zurich), Jurg Diemand (Zurich), Davide Martizzi (Berkeley) (25 February 2014). "A Globular Cluster Toward M87 with a Radial Velocity < -1000 km/s: The First Hypervelocity Cluster".
- ^ Gonzalez, Guillermo; Brownlee, Donald; Ward, Peter (July 2001). "The Galactic Habitable Zone: Galactic Chemical Evolution". Icarus 152 (1): 185–200.
- ^ Sigurdsson, S.; Stairs, I. H.; Moody, K.; Arzoumanian, K. M. Z.; Thorsett, S. E. (2008). Fischer, D.; Rasio, F. A.; Thorsett, S. E.; Wolszczan, A., eds. "Planets Around Pulsars in Globular Clusters". Extreme Solar Systems, ASP Conference Series, proceedings of the conference held 25–29 June 2007, at Santorini Island, Greece 398: 119.
- ^ Spurzem, R. et al. (May 2009). "Dynamics of Planetary Systems in Star Clusters". The Astrophysical Journal 697 (1): 458–482.
General resources
- NASA Astrophysics Data System has a collection of past articles, from all major astrophysics journals and many conference proceedings.
- SCYON is a newsletter dedicated to star clusters.
- MODEST is a loose collaboration of scientists working on star clusters.
- Binney, James; Tremaine, Scott (1987). Galactic Dynamics (First ed.). Princeton, New Jersey: Princeton University Press.
- Heggie, Douglas; Hut, Piet (2003). The Gravitational Million-Body Problem: A Multidisciplinary Approach to Star Cluster Dynamics. Cambridge University Press.
- Spitzer, Lyman (1987). Dynamical Evolution of Globular Clusters. Princeton, New Jersey: Princeton University Press.
Review articles
- Elson, Rebecca; Hut, Piet; Inagaki, Shogo (1987). Dynamical evolution of globular clusters. Annual review of astronomy and astrophysics 25 565. Bibcode: 1987ARA&A..25..565E
- Meylan, G.; Heggie, D. C. (1997). Internal dynamics of globular clusters. The Astronomy and Astrophysics Review 8 1. Bibcode: 1997A&ARv...8....1M
External links
- Globular Clusters, SEDS Messier pages
- Milky Way Globular Clusters
- Catalogue of Milky Way Globular Cluster Parameters by William E. Harris, McMaster University, Ontario, Canada
- A galactic globular cluster database by Marco Castellani, Rome Astronomical Observatory, Italy
- Key stars have different birthdays article describes how stars in globular clusters are born in several bursts, rather than all at once
- Globular Clusters Blog News, papers and preprints on Galactic Globular Clusters
- Clickable Messier Object table including globular clusters


text:
"Glee" actor Cory Monteith died of a mixed drug toxicity involving heroin and alcohol, according to Canadian authorities.
The British Columbia Coroners Service issued a statement Tuesday saying that post-mortem testing on Monteith included an autopsy and toxicological analysis, and that no other details were available at this time.
"There is no evidence to suggest that this is anything other than a most sad and tragic accident," Coroner Barbara McLintock said in a video released by the BC Coroner's service (see below).
U.S. & World
In the video statement McLintock goes on to offer "heartfelt condolences" to all of Monteith's family and friends. The Coroner's office confirmed Monday that they were fast-tracking the autopsy and toxicological analysis due to the intense public interest in the case.
Monteith, 31, was found dead in his room at the Fairmont Pacific Rim Hotel in Vancouver on Saturday after missing his scheduled checkout time.
The actor went out on Friday night with a male friend and two female friends but returned to his hotel room alone around 2:15 a.m., Vancouver police Constable Brian Montague said at a press conference Tuesday afternoon.
"This was an overdose and a tragic accident," Montague said, adding, "Our belief is that when he took the heroin he was alone." He went on to say that there was evidence in the room that was consistent with a drug overdose but did not provide details of exactly what was found at the scene.
Monteith's whereabouts Friday evening were also not disclosed because "there's nothing to suggest that that has anything to do with our investigation," Montague said. Police believe the actor had been dead for several hours when he was found.
The investigation into this death by the BC Coroners Service is continuing and a full Coroner's Report will be issued once the case is concluded.
Monteith admitted himself to a treatment facility in April for substance addiction and asked for privacy as he took steps toward recovery, a representative said. Lea Michele, Monteith's "Glee" co-star and real-life girlfriend, told People magazine at the time that she loved and supported him and was proud he was seeking help.
It was not Monteith's first time in rehab. He received treatment when he was 19 and had previously talked about his addiction struggles, saying he had a serious problem and took just "anything and everything."
He told Parade magazine in 2011 that he was "lucky to be alive."
Representatives issued a statement on Michele's behalf Tuesday afternoon:
"Lea is deeply grateful for all the love and support she's received from family, friends, and fans. Since Cory's passing, Lea has been grieving alongside his family and making appropriate arrangements with them. They are supporting each other as they endure this profound loss together. We continue to ask the media to respect the privacy of Lea and Cory's family."
Monteith was due to begin working on the fifth season of "Glee" in two weeks. How his absence will be handled in the Fox Network show about a high school singing club has yet to be announced.

subset: commoncrawl


text:
Kwesi Fraser necesitaba un nuevo diseño de logotipo y lanzó un concurso de diseño en 99designs.
Un ganador ha sido elegido entre 60 diseños de 22 diseñadores freelance.
Drink Fresh Juice
I used to work in marketing, on both the client side and agency side (account services), strategically developing promotional events and all the associated supporting collateral material. I moved to Grand Cayman less than a year ago from Brooklyn NYC and I am about to start my own company (with my fiance Kim.)
I am used to reviewing creative work and look forward to developing a sick logo for my mobile juice company.
My primary target will be business professionals 25 plus, who are health conscious and have limited time to break away from their desk to eat (much less options to choose from for a healthy snack or meal.) I will promote my services to this group as a way to boost output and maximize mental potential /stamina during the day.
My secondary targets will be tourists on island for a few hours to shop, eat and experience Cayman. To this group I will promote the benefits of juicing as well as the importance of supporting local farmers (as I am resourcing all of my produce from the island.)
Additional targets to consider include:
-the ill and those looking to improve their heath by juicing.
-the already health committed / dedicated people who make eating healthy a priority.
There are less that 5 other fresh juice places on the island and none of them have the juicer that I have and thus really only focus on smoothies. My juicer is a twin gear, stainless steel, masticating juicer which provides the maximum juice liquid and maximum nutrient yield. They also don't deliver, so to that regard, I will be first to market with this concept.
I want to develop a logo for my company to be carried thru on a website, business cards, and the side of my mobile cart. I want to use FedEx as the bulls-eye...colors, font, and layout. When anybody sees the logo they should also feel FedEx....almost confuse the two.
With this logo I would like to see how we can use the first letter (or 2) in each word of the company name DRINK FRESH JUICE, and come off with a FedEx feel. I'm not sure if the entire name spelled out will give off the same feel...but ultimately I will have to put the name spelled out somewhere like in the web URL...so I am less concerned about the company name coming across as I am about the FedEx feel....
Simple enough?
Descubre cómo funciona un concurso de diseño u obtén más información sobre nuestros servicios de diseño de logo.


text:
By Kimberly Atkins
Dolan Media Newswires
BOSTON, MA--When President Bill Clinton was in office, he hoped to start a tradition: sitting down regularly with the nine justices of the U.S. Supreme Court.
But it never happened. According to Justice Ruth Bader Ginsburg, something came up.
"He was hit first with Paula Jones and then other things," Ginsburg told a crowd of about 2,000 at Southern Methodist University's Dedman School of Law in Dallas Monday, according to the Associated Press.
In her remarks, Ginsburg also lamented the polarization of the Supreme Court confirmation process, saying that she doubts she would have been confirmed if she were nominated today.
"I wish we could wave a magic wand and go back to the days when the process was bipartisan," Ginsburg told the crowd, adding: "Today, my ACLU connection would probably disqualify me."
Prior to her appointment as a federal judge on the DC Circuit, Ginsburg was general counsel for the ACLU, and helped found the group's Women's Right Project. Such a resume item would prove too controversial to win confirmation today, Ginsburg said. Even in 1993, White House officials prepping her for her Senate hearings warned her it would be a hot-button topic.
She told them: "There's nothing you can do to get me to bad mouth the ACLU."
Entire contents copyrighted © 2011 by Dolan Media Company.
Published: Thu, Sep 8, 2011


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By separating the tweeter and the woofer, component speaker systems improve the sound quality and overall audio experience in your car in three very big ways.
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text: Wednesday, February 01, 2012 APTA Seeks Volunteers for Vision Task Force At its June 2011 meeting, the House of Delegates adopted a motion charging the association to review and revise its current APTA Vision Sentence for Physical Therapy 2020 and APTA Vision Statement for Physical Therapy 2020 (HOD P06-00-24-35) to reflect the vision of the profession of physical therapy and its commitment to society beyond 2020. To fulfill this charge and facilitate the Board of Directors ability to create and implement a strategic plan to achieve the House-adopted vision, a Board-appointed Vision Task Force is being created. APTA members interesting in serving on this task force should complete and submit the volunteer application and CV by 11:59 PM ET February 15. Applications should be submitted via e-mail or by fax to 703/706-8519. E-mail APTA's Governance Department with questions regarding this task force or call 800/999-2782, ext 3256, for assistance. Comments I would love to participate Posted by kirk bradley on 2/4/2012 11:52 AM


text: Nine driving offences you didn't know were illegal There are numerous rules and restrictions around driving, ranging from alcohol consumption to speed limits. But did you know these nine common driving habits are actually illegal? 1. Parking the wrong way round at night This is a driving offence under rule 248 of the Highway Code, which states You MUST NOT park on a road at night facing against the direction of the traffic flow unless in a recognised parking space. Shutterstock other Buy a Photo 2. Flashing your lights to give way Flashing your lights to allow other drivers to go can be considered a driving offence if an accident results from doing so. Headlight flashes should only be used to warn drivers of your presence on the road. Shutterstock other Buy a Photo 3. Hogging the middle lane of the motorway Hogging the middle lane of the motorway is an offence, listed under careless driving. New laws introduced in 2013 allow police officers to hand out on-the-spot fines of 100 and three penalty points to lane-hoggers. Shutterstock other Buy a Photo 4. Beeping your horn at certain hours Beeping your horn between 11.30pm and 7am in a built-up area is an illegal driving offence that you may not be aware of. Shutterstock other Buy a Photo View more Page 1 of 3


text:
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• We also offer alterations for garments purchased elsewhere. Please call us to confirm availability, as we are extremely busy during our high seasons.
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To help you look your best and give you peace-of-mind during your special occasion, Seng Couture offers professional on-site dressing services for the Bride, Mother of the Bride/Groom, the Bridal Party, and Bar Bat Mitzvah occasions. We will see to every detail and to all of your needs so that you look and feel beautiful on the day of your event. For pricing and availability, please contact us via phone or email to inquire.
All Dressing Services must be confirmed and booked at least 2 months in advance before occasion


text:
Red Sox - 320 180 000 - 14 16 0 Cleveland - 100 000 000 - 1 5 1
Lester last struck out as many as 12 batters on September 13, 2010, when he fanned 12 Mariners. He allowed singles to the first two Cleveland batters in the first inning - one of them scored on a sac fly - but was superb after that. He struck out the side in the third and fifth innings, and punched out 10 of his last 14 batters.
For the offense, Carl Crawford doubled three times, scored twice, and drove in three runs, before being pulled after the eight-run explosion because his wrist was bothering him a little bit.
Adrian Gonzalez hit his 13th home run in the first inning, and drove in four runs. Mike Aviles reached base five times and scored three runs. Dustin Pedroia also scored three times.
Danny Valencia made his Red Sox debut, going 0-for-4 with a sacrifice fly.
Jon Lester / Corey Kluber
Ellsbury, CFDavid Ortiz (strained right Achilles tendon) had hoped to return to the lineup today, but that will likely not happen.
Crawford, LF
Pedroia, 2B
Gonzalez, 1B
Ross, RF
Saltalamacchia, DH
Aviles, SS
Valencia, 3B
Shoppach, C
I'm only so-so. ... Still pretty sore.Ortiz has been on the DL since July 17. He still leads the American League in OBP (.414), slugging (.609), and OPS (1.024).


text:
Problem solving skills, mentoring, help foster children succeed
Foster children who receive mentoring and training in anger management, problem solving and healthy communication are more likely to succeed — to avoid decisions that land them in residential treatment programs, or shuffle them from foster home to foster home, or cause them to drop out of school — and possibly reunite with their biological families, according to a six-year study by University of Colorado School of Medicine researchers.
Their report, published in Pediatrics, followed 149 ethnically diverse children between the ages of 9 and 11. Noting that children entering foster care often have emotional, behavioral, developmental and physical health problems — eligible foster children accounted for 41 percent of all children who received mental health services through a California medical program — the researchers looked at how to address those issues. Fifty children who received mentoring and skills training over a six-year period were compared to approximately 50 children who received typical community and social services.
The researchers found that the foster children in the mentoring program had 44% fewer placement changes between foster homes, and were 82% likelier to be reunited with their biological families.
"A decade of work and analysis shows that well-designed and supervised mentoring programs can be effective for high-risk youth," Taussig said.


text:
The fat acceptance debate is one fraught with logical fallacies. People who don't support fat acceptance cite a variety of reasons.
Fat is ugly.
Being fat can't be healthy.
Fat people use up a disproportionate amount of resources.
Accepting fat people is acknowledging fat is okay.
The list goes on.
Health at Every Size is a movement dating back to the '60s and, simply put, it states that aggressive dieting rarely works, and is emotionally and physically damaging. The idea is that everyone has their own natural metabolic weight ranges, and through intuitive eating, paying attention to what one's body needs, and providing nutritious and varied meals combined with enjoyable exercise, the body will find its own set weight point for optimum metabolism and health. In short, many attempts to lose weight through drastic dieting do not lead to successful, sustained weight loss over time, and optimal mental and physical health comes from self-acceptance.
Self acceptance is the only real link between fat acceptance and HAES. HAES is a lifestyle. HAES is a choice people make for themselves to promote their own health and well-being. Fat acceptance is none of those things.
Fat acceptance is a movement. It is based in justice, equal rights, fairness, ethics, and inclusivity.
Fat acceptance isn't a bunch of Tumblrinas HAES-binging on cupcakes screaming "MUH CURVES".
Fat acceptance isn't about hating thin people.
Fat acceptance isn't about hating "small fats" for not having as tough a time as fatter women.
Fat acceptance isn't about food.
Fat acceptance isn't about dieting.
Fat acceptance isn't even about science. Science is HAES territory.
Fat acceptance is a campaign to end weight discrimination and the negative stigma perpetuated by societal pressures of consumerism and mass media.
Fat acceptance is the idea that no one, regardless of size, deserves to be treated poorly.
No, you DON'T have to find us attractive. Attractiveness has nothing to do with equitable treatment.
No, you DON'T get to worry about our health status. Health status has nothing to do with fair treatment.
… And there's the rub. When you lump HAES in with fat acceptance, you are opening the door for all sorts of fallacious arguments. It's food for the Concern Trolls who seek to delegitimize the fat acceptance movement with health science "proving" fat is unhealthy and therefore is not an acceptable way to live. It also invites in all of the simplistic calories in/calories out "nutrition experts" saying that, if we're unhappy, it's because we aren't taking the necessary steps to make our lives better.
How people appear, how they feel, how abled they are, what their BMI is, none of that matters. A fat person with diabetes deserves to be treated the same as a fat person with perfect metabolic health, a thin person with great metabolic health, or a thin person with terrible metabolic health.
Health. Is. Not. Relevant. Period. This is an issue of discrimination and tolerance. Using health status to justify why we shouldn't treat everyone with the same care and compassion is a slippery slope. Making assumptions about a person's lifestyle and then judging people based on those assumptions is unconscious, societally-bred prejudice at best, and at worst it is open hostility toward someone who does not conform to a prescribed "normal".
If we open up HAES as a talking point in any debate about the fat acceptance movement, we are not just opening up the field in which detractors can erect straw men; we are giving them the straw for free, and showing them the best and most efficient means for construction. People will start trying to prove that being fat is bad for your health. They will turn the conversation from a social justice issue to a health science issue. It will become a discussion of will power, of laziness, of lack of motivation. It will become a conversation of "but we're just trying to help motivate you to make better life choices!"
Fuck life choices. Who's job is it to police life choices? Especially if said policing is, in actuality, just inferring one's life choices with a cursory glance, confirming "yup, that's a fatty!", and then telling them to feel bad for it.
It's my body. It changes. It gets bigger, it gets smaller. Why? Fuck you, that's why. It does not matter. It's my own goddamned business. My body, body choices, and health status do not factor into the reality that I am a human being, a member of society, and deserve to be recognized and respected as such.
"If you worked out as hard as you blogged, you wouldn't need to blog anymore."
Opponents will bring it back to metabolic health, again and again, because FACTS SCIENCE FATTY LIVER DEATH FAT DIABEETUS is the only real leg they have to stand on, and a hollow one at that, because again:
HEALTH STATUS IS IRRELEVANT in issues of basic human rights and social justice.
Yes, there are many fat people who practice HAES. There are thin people who practice HAES as well. HAES has self-acceptance at its core; it plays a key role in helping people overcome disordered eating, low self-esteem, and other symptoms of fat discrimination.
Fat acceptance is the movement that will end fat discrimination.
Here's a space cupcake:


text:
The last day of the Round of 16 was as exciting as it could get. China gave Lithuania all it could handle, and the winner of the South American clash wasn't known until the final seconds.
The day started with Lithuania, Group D winners, playing China, who won one game in their group play and still qualified. China came out strong in the beginning and managed to lead Lithuania most of the first half until Lithuanian star Linas Kleiza stepped up once again and had Lithuania on top by 5 at halftime. The third quarter was all Lithuania, yet as the fourth started, the Chinese slowly started getting back into the game, yet Kleiza, 30 points and 9 rebounds, scored 13 of Lithuania's 14 points in the last quarter, keeping Lithuania on top comfortably everytime China got closer, and won the game 78-67. Liu Wei had 21 points for China.
The nightcap for the day was a South American classic rival match between Argentina and Brazil. After giving the American team a fit in group play, it was assumed that Brazil would make things hard if not win as well this game and play Lithuania. The game was even by the end of the first quarter, with Luis Scola and Carlos Delfino doing the job for Argentina while Brazil's Marcos Huertas and Leando Barbosa scoring 20 of their team's 25 points in the first quarter. The game continued to be as equal, with no team able to lead by a lot and by the third quarter the game was tied again. Insert Hernan Jasen for Argentina, who tied the score again after Barbosa knocking down 2 straight 3 pointers. Yet Scola's 37 points overcame Huertas' 32 points and his desperation three pointer to cut the lead to 2 points with 2 seconds left, to give Argentina a 93-89 win and a berth in the quarters to face Lithuania. Delfino had 20 points (3 for 3 on 3 pointers) and Jasen had 15 for Argentina, while Barbosa had 20 points for Brazil