Multiband Optical Observation of P/2010 A2 Dust Tail
  An inner main-belt asteroid, P/2010 A2, was discovered on January 6th, 2010. Based on its orbital elements, it is considered that the asteroid belongs to the Flora collisional family, where S-type asteroids are common, whilst showing a comet-like dust tail. Although analysis of images taken by the Hubble Space Telescope and Rosetta spacecraft suggested that the dust tail resulted from a recent head-on collision between asteroids (Jewitt et al. 2010; Snodgrass et al. 2010), an alternative idea of ice sublimation was suggested based on the morphological fitting of ground-based images (Moreno et al. 2010). Here, we report a multiband observation of P/2010 A2 made on January 2010 with a 105 cm telescope at the Ishigakijima Astronomical Observatory. Three broadband filters, $g'$, $R_c$, and $I_c$, were employed for the observation. The unique multiband data reveals that the reflectance spectrum of the P/2010 A2 dust tail resembles that of an Sq-type asteroid or that of ordinary chondrites rather than that of an S-type asteroid. Due to the large error of the measurement, the reflectance spectrum also resembles the spectra of C-type asteroids, even though C-type asteroids are uncommon in the Flora family. The reflectances relative to the $g'$-band (470 nm) are 1.096$\pm$0.046 at the $R_c$-band (650 nm) and 1.131$\pm$0.061 at the $I_c$-band (800 nm). We hypothesize that the parent body of P/2010 A2 was originally S-type but was then shattered upon collision into scaterring fresh chondritic particles from the interior, thus forming the dust tail. 
Junhan Kim, Masateru Ishiguro, Hidekazu Hanayama, Sunao Hasegawa,   Fumihiko Usui, Kenshi Yanagisawa, Yuki Sarugaku, Jun-ich...
astro-ph.EP