The Active Chromosphere Binary HD 17433 (VY Arietis)
Abstract
The sixth-magnitude K star HD 17433 (VY Ari) is shown to be an active-chromosphere binary with an orbital period of 13.198 days. A photometric (rotational) period of 17.4 days is indicated by the existing photometry, implying that HD 17433 is not in synchronous rotation. In the optical, H-alpha is seen in emission, with variable profile and intensity; He I lambda-5876 is present in absorption. IUE observations show chromospheric and transition-region emission lines with surface fluxes up to 200 times greater than those observed in the quiet sun. The luminosity and radius are appropriate for a subgiant, and the kinematics suggest Pleiades group membership. The presence of a lithium absorption feature indicates it may either be a young object, possibly a pre-main sequence star or an evolved spotted RS CVn system. Interpretations from the optical measurement of the magnetic field strength of HD 17433 are given.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1989
- DOI:
- 10.1086/167360
- Bibcode:
- 1989ApJ...339.1059B
- Keywords:
-
- Binary Stars;
- Chromosphere;
- K Stars;
- Magnetic Stars;
- Pre-Main Sequence Stars;
- Stellar Activity;
- Emission Spectra;
- H Alpha Line;
- Line Spectra;
- Lithium;
- Magnetic Flux;
- Radial Velocity;
- Stellar Orbits;
- Ultraviolet Spectra;
- Astrophysics;
- STARS: BINARIES;
- STARS: CHROMOSPHERES;
- STARS: EMISSION-LINE;
- STARS: INDIVIDUAL HENRY DRAPER NUMBER: HD 17433;
- STARS: INDIVIDUAL CONSTELLATION NAME: VY ARIETIS;
- STARS: MAGNETIC;
- STARS: PRE--MAIN-SEQUENCE