The Coronae of AB Dor and V471 Tau: Youth vs Tidal Spin-Up

García-Alvarez, D.; Drake, J. J.; Lin, L.; Kashyap, V.
Referencia bibliográfica

Stars as suns : activity, evolution and planets, Proceedings of the 219th symposium of the International Astronomical Union held during the IAU General Assembly XXV, Sydney, Australia, 21-25 July 2003. Edited by A.K. Dupree and A.O. Benz. San Francisco, CA: Astronomical Society of the Pacific (ASP), 2004. Available on companion CD-ROM., p.858

Fecha de publicación:
1
2004
Número de autores
4
Número de autores del IAC
0
Número de citas
0
Número de citas referidas
0
Descripción
We report on an analysis of high resolution Chandra spectra of two stars with very similar spectral types and rotation rates but with very different evolutionary histories. AB Doradus is a young relatively bright (V=6.9) rapidly rotating (P=0.51d) late-type star (dK0-2) that is just evolving onto the main sequence. V471 Tau is a post-common envelope pre-cataclysmic binary system and is comprised of a cool main-sequence chromospherically active dwarf (dK2V=9.5) and a degenerate hot white dwarf in an orbit with a separation of only 3.4 R* and P=0.52d. Chandra HETGS spectra of AB Dor and LETGS spectra V471 Tau caught both objects in relatively quiescent non-flaring states and show them to have very similar X-ray spectra. Using a new technique based on the ratios of prominent lines of highly ionized Fe and resonance lines of He-like and H-like ions we have determined the temperature structure and chemical composition of the emitting plasma in both coronae. Both stars have coronae that are relatively Ne-rich and Fe-poor similar to the abundances found from high-resolution spectra of other active stars. We compare and constrast the two coronae in the context of outer atmosphere structure and the rich emerging pattern of coronal abundance anomalies.