Differential Rotation of the Active G5 V Star κ¹ Ceti: Photometry from the MOST Satellite

Author(s)

Slavek M. Rucinski, Gordon A. H. Walker, Jaymie M. Matthews, Rainer Kuschnig, Sergey V. Marchenko, Evgenya Shkolnik, David A. Bohlender, David B. Guenther, Anthony F J Moffat, Dimitar Sasselov, Werner Wolfgang Weiss

Abstract

About 30.5 days of nearly uninterrupted broadband photometry of the solar‐type star κ¹ Ceti, obtained with the MOST (Microvariability and Oscillations of Stars) satellite, shows evidence for two large starspots with different rotation periods of 8.9 and ∼9.3 days ( ). Ground‐based measurements of Ca ii

H and K emission in 2002 and 2003 reveal variations in chromospheric

activity with a period of about 9.3 days. The data were obtained during

the MOST commissioning phase. When the data are combined with

historical observations, they indicate that the 9.3 day spot has been

stable in its period for over 30 yr. The photometry, with a sampling

rate of approximately once per minute, was also used to search for

acoustic (p‐mode) oscillations in the star. We detect no clear evidence for p‐modes in the κ¹

Ceti photometry, with a noise level around 7–9 μmag at frequencies in

the range of 0.5–4 mHz (3 σ detection limit of 21–27 μmag). There were

no flares or planetary transits during 30.5 days of MOST

monitoring with light amplitudes greater than 2 mmag (durations >200

minutes) and 3 mmag (2–200 minute durations). While this rules out any

close‐in planets with Jupiter diameters ≥0.5 and orbital inclinations

close to 90°, the scatter in differential radial velocities permit a

close giant planet in a more highly inclined orbit.

Organisation(s)

Department of Astrophysics

External organisation(s)

University of Toronto, University of British Columbia (UBC), National Research Council Canada (NRC-CNRC), Saint Mary's University, University of Montreal, Harvard-Smithsonian Center for Astrophysics, Western Kentucky University

Journal

Publications of the Astronomical Society of the Pacific

Volume

116

Pages

1093-1104

No. of pages

12

ISSN

0004-6280

DOI

https://doi.org/10.1086/426928

Publication date

2004

Peer reviewed

Yes

Austrian Fields of Science 2012

103003 Astronomy

Portal url

https://ucrisportal.univie.ac.at/en/publications/8ce6852a-d6b8-4f8f-a936-5e1d7aeb9f36