SIMBAD references

2018MNRAS.481L.115U - Mon. Not. R. Astron. Soc., 481, L115-L119 (2018/November-3)

Pulsational activity changes in the Cepheid Polaris (α UMi) during 2017-2018: a new amplitude decrease.


Abstract (from CDS):

We present an analysis of 67 recent spectra of α UMi (Polaris) obtained in 2017 August-2018 May. Frequency analysis reveals an increase in the pulsation period to 3^ d^.970662 relative to our 2016/17 observations. The radial velocity amplitude was found to be 3.87 km s–1 in the last half of 2017, but dropped to 2.80 km s–1 during the first half of 2018. In comparison with 4.16 km s–1 observed by us in 2015, the observations reveal a new decrease in pulsation amplitude. Such a result is unexpected given that a gradual amplitude growth was evident during the last decade. The average values of T_ eff_ were found to be 6017 K and 6039 K, respectively, but the T_ eff_ amplitude has increased despite the decrease in radial velocity amplitude. Possibly that could be explained by the presence of starspots on the Cepheid's surface.

Abstract Copyright: © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): stars: variables: Cepheids - stars: atmospheres - techniques: radial velocities - stars: individual: a UMi

Simbad objects: 5

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