New bright optical spectrophotometric standards: A-type stars from the STIS Next Generation Spectral Library
Abstract
Exoplanets have sparked interest in extremely high signal-to-noise ratio spectroscopic observations of very bright stars, in a regime where flux calibrators, in particular DA white dwarfs, are not available. We argue that A-type stars offer a useful alternative and reliable space-based spectrophotometry is now available for a number of bright ones in the range 3 < V < 8 mag. By means of comparing observed spectrophotometry and model fluxes, we identify 18 new very bright trustworthy A-type flux standards for the optical range (400-800 nm), and provide scaled model fluxes for them. Our tests suggest that the absolute fluxes for these stars in the optical are reliable to within 3 per cent. We limit the spectral range to 400-800 nm, since our models have difficulties to reproduce the observed fluxes in the near-infrared and, especially, in the near-UV, where the discrepancies rise up to ∼10 per cent. Based on our model fits, we derive angular diameters with an estimated accuracy of about 1 per cent.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2016
- DOI:
- 10.1093/mnras/stv2518
- arXiv:
- arXiv:1511.02951
- Bibcode:
- 2016MNRAS.455.3864A
- Keywords:
-
- stars: atmospheres;
- stars: fundamental parameters;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- source files include low-resolution model fluxes