Surface imaging of HD 199178 ( V 1794 Cygni ) ⋆
نویسنده
چکیده
We present surface temperature maps for the FK Comae-type star HD 199178 (V1794 Cygni) calculated from high resolution spectra obtained in 1994 and 1995. The spot pattern evolves, but all maps reveal a large cool spot remaining nearly at the same high latitude. The main spot is 1200 – 1600 K cooler than the mean surface temperature. The observed slightly flat bottomed absorption lines would usually be interpreted as evidence for a large cool polar spot. We argue that antisolar surface differential rotation offers a better explanation for the box like shape of the line profiles. However, we do not find conclusive evidence for antisolar differential rotation and note that there are still other possible explanations for the slightly flat bottomed line profiles.
منابع مشابه
Time series analysis of V 1794 Cygni long–term photometry
Standard Johnson UBVRI photometry of V 1794 Cyg (HD199178) between 1975 and 1995 is analysed. Instead of the traditional constant period ephemeris, we determine the seasonal periodicities (Pphot) and the primary and secondary minima epochs (tmin,1, tmin,2) of the normalized UBVRI magnitudes using the three stage period analysis (TSPA) and complementary methods. Our tmin,1 and tmin,2 estimates w...
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