DOI: https://doi.org/10.18524/1810-4215.2019.32.182238

PULSATIONAL ACTIVITY OF THE SMALL–AMPLITUDE CEPHEID POLARIS (α UMi) IN 2018-2019

I. A. Usenko, A. S. Miroshnichenko, S. Danford, V. V. Kovtyukh

Анотація


We present the results of an analysis
of 20 spectra of α UMi (Polaris) obtained in September
2018 – January 2019 using 0.81m telescope of the
Three College Observatory (TCO), North Carolina,
USA. Frequency analysis displays an increase of the
pulsational period up to 3.68 min in comparison to
the August - December 2017 - January - May 2018
observational sets, and it come to 3.973216 days. The
systemic velocity (γ – velocity) is equal to −11.75
kms −1 . The radial velocity amplitude rose to 3.50
kms −1 and actually returned to the previous values
of 3.43, 3.31, and 3.81 kms −1 , respectively, found
from the August - December 2016, January - March
2017 and August - December 2017 sets. The radial
velocity’s amplitude growth tendency still remains.
The average T eff = 6051±22 K shows a growth toward
the value found from the 2005 – 2007 observational
sets and probably has a tendency toward the T eff
growth. The joint TCO and Hermes radial velocity
measurements during the last four years show the
changes of Polaris’ pulsational amplitude.

 


Ключові слова


Stars: radial velocities; Cepheids: effective temperatures; Cepheids: pulsational periods; Cepheids: α UM

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Посилання


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