4.6 Article

BRITE photometry and STELLA spectroscopy of bright stars in Auriga: Rotation, pulsation, orbits, and eclipses

期刊

ASTRONOMY & ASTROPHYSICS
卷 644, 期 -, 页码 -

出版社

EDP SCIENCES S A
DOI: 10.1051/0004-6361/202039310

关键词

binaries: general; stars: rotation; stars: activity; stars: fundamental parameters; stars: oscillations; stars: late-type

资金

  1. State of Brandenburg (MWFK)
  2. German Federal Ministry of Education and Research (BMBF)
  3. National Science Centre (NCN) [2016/21/B/ST9/01126]
  4. Silesian University of Technology: Higher Education Funding for Statutory Activities and Rector Grant [02/140/RGJ20/0001]
  5. NSERC (Canada)
  6. Natural Sciences and Engineering Research Council (NSERC) of Canada
  7. Polish NCN Grant [2015/18/A/ST9/00578]

向作者/读者索取更多资源

Context. Knowing rotational and pulsational periods across the Hertzsprung-Russell diagram is of top priority for understanding stellar activity as a function of time.Aims. We aim to determine periods for bright stars in the Auriga field that are otherwise not easily accessible for ground-based photometry.Methods. Continuous photometry with up to three BRITE satellites was obtained for 12 targets and subjected to a period search. Contemporaneous high-resolution optical spectroscopy with STELLA was used to obtain radial velocities through cross correlation with template spectra as well as to determine astrophysical parameters through a comparison with model spectra.Results. The Capella red light curve was found to be constant over 176 days with a root mean square of 1 mmag, but the blue light curve showed a period of 10.1 +/- 0.6 d, which we interpret to be the rotation period of the G0 component. From STELLA we obtained an improved orbital solution based on 9600 spectra from the previous 12.9 yr. We derive masses precise to approximate to 0.3% but 1% smaller than previously published. The BRITE light curve of the F0 supergiant epsilon Aur suggests 152 d as its main pulsation period, while the STELLA radial velocities reveal a clear 68 d period. An ingress of an eclipse of the zeta Aur binary system was covered with BRITE and a precise timing for its eclipse onset derived. A possible 70 d period fits the proposed tidal-induced, nonradial pulsations of this ellipsoidal K4 supergiant. eta Aur is identified as a slowly pulsating B (SPB) star with a main period of 1.29 d and is among the brightest SPB stars discovered so far. The rotation period of the magnetic Ap star theta Aur is detected from photometry and spectroscopy with a period of 3.6189 d and 3.6177 d, respectively, likely the same within the errors. The radial velocities of this star show a striking non-sinusoidal shape with a large amplitude of 7 km s(-1). Photometric rotation periods are also confirmed for the magnetic Ap star IQ Aur of 2.463 d and for the solar-type star kappa (1) Cet of 9.065 d, and also for the B7 HgMn giant beta Tau of 2.74 d. Revised orbital solutions are derived for the eclipsing SB2 binary beta Aur, which replaces the initial orbit dating from 1948 for the 27-year eclipsing SB1 epsilon Aur, and for the RS CVn binary V711 Tau, for which a spot-corrected orbital solution was achieved. The two stars nu Aur and iota Aur are found to be long-term, low-amplitude RV and brightness variables, but provisional orbital elements based on a period of 20 yr and an eccentricity of 0.7 could only be extracted for nu Aur. The variations of iota Aur are due to oscillations with a period of approximate to 4 yr.

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