Effective temperature and radial velocity of the small-amplitude Cepheid   Polaris (alpha UMi) in 2015
  We present the results of an analysis of 21 spectra of alpha UMi (Polaris) obtained in September - December 2015. Frequency analysis shows an increase of the pulsation period up to 8.6 min in comparison to the 2007 observational set. The radial velocity amplitude comes to 4.16 km s^-1, and it approximately twice the one found in 2007. The average Teff = 6017 K, and it is close to the value determined for the 2001-2004 set. Therefore Polaris moves to the red edge of the Cepheid instability strip (CIS) 
I. A. Usenko, V. V. Kovtyukh, A. S. Miroshnichenko, and S. Danford
astro-ph.SR