SPECTROSCOPIC INVESTIGATIONS OF THE POLARIS (α UMi) SYSTEM: RADIAL VELOCITY MEASUREMENTS, NEW ORBIT, AND COMPANION INFLUENCE FOR THE CEPHEID POLARIS Aa PULSATION ACTIVITY

Автор(и)

  • I. A. Usenko Odessa National University, Astronomical Observatory, Mykolaiv Astronomical Observatory, Ukraine
  • A. S. Miroshnichenko Dept. of Physics and Astronomy, University of North Carolina at Greensboro,, United States
  • S. Danford Dept. of Physics and Astronomy, University of North Carolina at Greensboro, United States
  • V. V. Kovtyukh Odessa National University, Astronomical Observatory, Ukraine
  • D. G. Turner Dept. of Astronomy and Physics, Saint Mary’s University, Canada

DOI:

https://doi.org/10.18524/1810-4215.2020.33.216289

Ключові слова:

α UMi (Polaris Aa and Polaris Ab) system, radial velocities, Polaris Aa effective temper- atures, Polaris Aa pulsational period and amplitude, orbital elements

Анотація

Thirty three spectra of the Polaris
system obtained in August–December 2019 and
February–April 2020 at the 0.81m telescope of the
Three College Observatory (TCO, North Carolina,
USA) were used to determine the radial velocities (RV)
and effective temperature of the Cepheid Polaris Aa.
These new data have been added to the entire Polaris
system RV data collection (over 2,500 measurements)
to compute a new orbit of the Polaris Aa companion.
Furthermore we have used our eight observational
datasets taken in 2015–2020 and eight datasets taken
in 2011–2018 by Anderson (2019) to check for possible
influence of the orbital motion of Polaris Ab on the
Polaris Aa pulsational activity. It was found that the
mean pulsational period in 2015–2020 was quite stable
(3.976±0.012 days), while the pulsational amplitude
showed evident changes: a growth before HJD 2457350
with a following decrease. This fact could be due to
the Polaris Ab passing through the periastron.

Посилання

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Опубліковано

2020-11-14

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Astrophysics