SPECTROSCOPIC INVESTIGATIONS OF GALACTIC CLUSTERS WITH ASSOCIATED CEPHEID VARIABLES. I. POLARIS CLUSTER AND α UMI

Автор(и)

  • I. A. Usenko Astronomical Observatory, Odessa National University, Mykolaiv Astronomical Observatory, Україна
  • A. S. Miroshnichenko Dept. of Physics and Astronomy, University of North Carolina at Greensboro, США
  • S. Danford Dept. of Physics and Astronomy, University of North Carolina at Greensbo, США
  • V. V. Kovtyukh Astronomical Observatory, Odessa National University, Україна
  • D. G. Turner Dept. of Physics and Astronomy, Saint Mary’s University, Канада
  • A. V. Shulga Mykolaiv Astronomical Observatory, Україна
  • Yu. I. Protsyuk Mykolaiv Astronomical Observatory, Україна

DOI:

https://doi.org/10.18524/1810-4215.2018.31.145379

Ключові слова:

Open clusters, Stars, radial velocities, GAIA parallaxes, Cepheids, main-sequence stars, effective temperatures, distances, α UMi

Анотація

We present the results of an analysis of the spectra of nine so called Polaris cluster A−FV stars
obtained during 2016 - 2018. Radial velocities (RV) and GAIA DR 18 parallaxes-distances for these stars allow us to determine their membership in the cluster and to construct its 3D kinematic model. However Teff for four stars determined spectroscopically give cause
for doubts about the GAIA DR 18 parallaxes accuracy. The comparison between their MV and distances with the those from Pecaut & Mamajek (2013) calibrations shows significant differences for the objects with parallaxes less than 8 mas. The differences in distances
increase exponentially with decreasing parallax. These facts indicate an unreliability of the GAIA DR2 parallx measurements of less than 10 mas. We estimated the distance to Polaris B to be 104.2 pc. 

Посилання

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Опубліковано

2018-10-23

Номер

Розділ

Астрофізика (зоряні атмосфери, взаємодіючі подвійні системи, змінні зорі)