The fundamental parameters of the roAp star α Circini
- 30 April 2008
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 386 (4), 2039-2046
- https://doi.org/10.1111/j.1365-2966.2008.13167.x
Abstract
We have used the Sydney University Stellar Interferometer to measure the angular diameter of α Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, α Cir being the brightest member of its class. We used the new and more accurate Hipparcos parallax to determine the radius to be 1.967 ± 0.066 R⊙. We have constrained the bolometric flux from calibrated spectra to determine an effective temperature of 7420 ± 170 K. This is the first direct determination of the temperature of an roAp star. Our temperature is at the low end of previous estimates, which span over 1000 K and were based on either photometric indices or spectroscopic methods. In addition, we have analysed two high-quality spectra of α Cir, obtained at different rotational phases and we find evidence for the presence of spots. In both spectra we find nearly solar abundances of C, O, Si, Ca and Fe, high abundance of Cr and Mn, while Co, Y, Nd and Eu are overabundant by about 1 dex. The results reported here provide important observational constraints for future studies of the atmospheric structure and pulsation of α Cir.This publication has 41 references indexed in Scilit:
- The Complementary Roles of Interferometry and Asteroseismology in Determining the Mass of Solar‐Type StarsThe Astrophysical Journal, 2007
- First Magnetic Doppler Images of a roAp starCommunications in Asteroseismology, 2007
- The discovery of 8.0-min radial velocity variations in the strongly magnetic cool Ap star HD 154708, a new roAp starMonthly Notices of the Royal Astronomical Society, 2006
- Detection of an extraordinarily large magnetic field in the unique ultra-cool Ap star HD 154708Astronomy & Astrophysics, 2005
- Stellar model atmospheres with magnetic line blanketingAstronomy & Astrophysics, 2005
- A catalog of stellar magnetic rotational phase curvesAstronomy & Astrophysics, 2005
- Multi-element abundance Doppler imaging of the rapidly oscillating Ap star HR 3831Astronomy & Astrophysics, 2004
- The core-wing anomaly of cool Ap starsAstronomy & Astrophysics, 2001
- Limb-darkening corrections for interferometric uniform disc stellar angular diametersMonthly Notices of the Royal Astronomical Society, 2000
- Discovery of magnetic field in four southern AP stars.Publications of the Astronomical Society of the Pacific, 1975