LO Peg in 1998: star-spot patterns and differential rotation

JR Barnes, Andrew Collier Cameron, TA Lister, GR Pointer, MD Still

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

We present Doppler images of the young K5V-K7V rapid rotator LO Peg from seven nights of continuous spectroscopy obtained in 1998 from July 04 to July 10. The images reveal the presence of a strong polar cap with appendages extending to mid-latitudes, but no star-spots are seen below 15degrees. We briefly discuss the distribution of spots in light of recent flux transport simulations, which are able to reproduce the observed latitude dependence. With the full time series of spectra, of which 314 are useful, many phases are observed three times over the seven nights of observations. Using star-spots as tracers of a solar-like latitudinal differential rotation in our image reconstructions, we find that the equatorial regions complete one more rotation than the polar regions every 181 +/- 35 d. LO Peg is the second coolest star for which such a measurement has been made using indirect imaging methods. The degree of latitudinal shear is less than that seen in G and early K dwarfs, suggesting a trend in which differential rotation decreases with stellar mass in (pre-)main-sequence objects.

Original languageEnglish
Pages (from-to)1501-1508
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume356
Issue number4
DOIs
Publication statusPublished - 1 Feb 2005

Keywords

  • line : profiles
  • methods : data analysis
  • stars : activity
  • stars : atmospheres
  • stars : individual : LO Peg (BD+22 4409)
  • stars : late-type
  • MAIN-SEQUENCE STARS
  • DUAL-SITE OBSERVATIONS
  • G-DWARFS
  • DOPPLER IMAGES
  • ACTIVE STARS
  • AB DORADUS
  • COOL STARS
  • BD+22-DEGREES-4409
  • EVOLUTION
  • YOUNG

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