On the reliability of measuring differential rotation of spotted stars

Zsolt Kovári, János Bartus, Levente Kriskovics, Krisztián Vida, Katalin Oláh

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Cross-correlation of consecutive Doppler images is one of the most common techniques used to detect surface differential rotation (hereafter DR) on spotted stars. The disadvantage of a single cross-correlation is, however, that the expected DR pattern can be overwhelmed by sudden changes in the apparent spot configuration. Another way to reconstruct the image shear using Doppler imaging is to include a predefined latitude-dependent rotation law in the inversion code ('sheared image method'). However, special but not unusual spot distributions, such like a large polar cap or an equatorial belt (e.g., small random spots evenly distributed along the equator), can distort the rotation profile similarly as the DR does, consequently, yielding incorrect measure of the DR from the sheared image method. To avoid these problems, the technique of measuring DR from averaged cross-correlations using time-series Doppler images ('ACCORD') is introduced and the reliability of this tool is demonstrated on artificial data.

Original languageEnglish
Title of host publicationMagnetic Fields throughout Stellar Evolution
PublisherCambridge University Press
Pages198-199
Number of pages2
EditionS302
ISBN (Print)9781107044982
DOIs
Publication statusPublished - Aug 2014

Publication series

NameProceedings of the International Astronomical Union
NumberS302
Volume9
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221

Keywords

  • stars: activity
  • stars: imaging
  • stars: late-type
  • stars: spots

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science

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  • Cite this

    Kovári, Z., Bartus, J., Kriskovics, L., Vida, K., & Oláh, K. (2014). On the reliability of measuring differential rotation of spotted stars. In Magnetic Fields throughout Stellar Evolution (S302 ed., pp. 198-199). (Proceedings of the International Astronomical Union; Vol. 9, No. S302). Cambridge University Press. https://doi.org/10.1017/S1743921314002063