Rotational modulation and flares on RS CVn and BY DRA systems. II. IUE observations of BY Draconis and AU Microscopii.
Abstract
The modulation of the strong chromospheric and transition region lines over one cycle of the optical light curves of BY Dra and AU Mic is studied using IUE observations. The IUE observations were made from October 2-5, 1981 and include 7 short wavelength (SW) spectra and 13 long wavelength (LW) spectra. The integrated line flux data reveal that for BY Dra in the SW spectra there is modulation in the C IV, C II, O I, and He II lines and nonflare surface fluxes; and in the LW spectra, flares are detected in the Mg II and Fe II bands. It is observed that there is no modulation in AU Mic, and the optical photometry data reveal a poor correlation between optical flare strength and UV emission line enhancements. The differential emission measure curves for BY Dra and AU Mic are compared with solar curves. It is noted that both stars show the presence of hot material throughout their rotation period.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1987
- Bibcode:
- 1987A&A...174..139B
- Keywords:
-
- Flare Stars;
- Starspots;
- Stellar Flares;
- Stellar Rotation;
- Dwarf Stars;
- Iue;
- Late Stars;
- Light Curve;
- Solar Flares;
- Stellar Spectra;
- Astrophysics