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Doppler imaging of stellar surface structure
III. The X-ray source HD 116544 = IN Virginis
Received 17 June 1996 / Accepted 30 July 1996
We present the first Doppler image of the EXOSAT X-ray source EXO 1321.8-0203, recently identified to be a chromospherically active star exhibiting periodic light variations and consequently named IN Virginis. Our high-resolution spectra show IN Virginis to be a single-lined spectroscopic binary with an orbital period of 8.2 days, very strong Ca II emission, and an inverse P-Cygni type H line profile. A detailed spectrum synthesis yields a photospheric temperature of 4600 70 K and and slight overabundance of the heavy elements but otherwise solar abundances. We redetermine the photometric period from a new set of photometry obtained with a robotic photoelectric telescope in the years 1994 and 1995 and conclude that IN Virginis is more likely a K2-3 subgiant instead of a K5 dwarf or K4 subgiant as previously published.
The Doppler images from March 1994 show a cool polar spot that is dominated by a large appendage reaching a latitude of . Its average temperature difference, photosphere minus polar spot, is 1000 K. Additionally, three equatorial spots are clearly recovered but have 400 K. Possibly, we also detected a warm equatorial feature with -150 K. We emphasize that Doppler imaging of IN Virginis is very challenging because of both the small of the star (24.0 km s-1) and its relatively cool photosphere causing many weak absorption-line blends. Still, maps from the different lines appear encouragingly similar.
Key words: stars: activity of stars: imaging stars: individual: IN Vir stars: late-type stars: fundamental data
* Visiting Astronomer, Kitt Peak National Observatory, operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Science Foundation
Online publication: July 3, 1998