Distribution and evolution of starspots on the RS CVn binary II Pegasi in 2004

Y. Xiang, S.-H. Gu, A. Collier Cameron, J.R. Barnes

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Abstract

We present Doppler images of RS CVn-type binary II Peg based on two data sets obtained in 2004 February and November. In order to improve signal-to-noise ratio and reliability,we apply least-squares deconvolution technique to calculate average profiles from 2032 photospheric absorption lines. Both of the resulting surface images show a wide latitude distribution of starspots. Most spots are concentrated at a high-latitude belt above 60° and a low-latitude belt near equator. The starspots evolved dramatically between two observing runs, which may indicate shorter time-scale evolution in this epoch, especially for low-latitude belt. There is no stable preferred active longitude that can be found in our images. We also find out a possible phenomenon that the intermediate-latitude spot migrated poleward and merged with the high-latitude spot to make it stronger, which may reveal a more complex behaviour of starspots on II Peg. A potential change of orbital ephemeris zero-point was detected. This may imply an orbital period change of II Peg like other active close binaries.
Original languageEnglish
Pages (from-to)2307-2316
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume438
Issue number3
Early online date30 Dec 2013
DOIs
Publication statusPublished - 1 Mar 2014

Keywords

  • Stars: activity
  • Binaries: close
  • Stars: imaging
  • Stars: individual: II Peg
  • Starspots

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