Differential Rotation of the Active G5 V Star κ1Ceti: Photometry from theMOSTSatellite1

• Published in: Publications of the Astronomical Society of the Pacific Vol. 116; no. 826; pp. 1093 - 1104
• Main Authors: Rucinski, Slavek M., Walker, Gordon A. H., Matthews, Jaymie M., Kuschnig, Rainer, Shkolnik, Evgenya, Marchenko, Sergey, Bohlender, David A., Guenther, D. B., Moffat, Anthony F. J., Sasselov, Dimitar, Weiss, Werner W.
• Format: Journal Article
• Language: English
• Published: The University of Chicago Press 23.11.2004; 01.12.2004
• Subjects: Artificial satellites; Astronomical photometry; Light curves; Parametric models; Planetary orbits; Radial velocity; Rotation; Satellite orbits; Stars; Stellar rotation
• ISSN: 0004-6280; 1538-3873
• DOI: 10.1086/426928

About 30.5 days of nearly uninterrupted broadband photometry of the solar‐type star κ1Ceti, obtained with theMOST(Microvariability and Oscillations of Stars) satellite, shows evidence for two large starspots with different rotation periods of 8.9 and ∼9.3 days ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\Delta \Omega / \Omega \simeq 4\% $ \end{document} ). Ground‐based measurements of CaiiH 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 theMOSTcommissioning 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 forp‐modes in the κ1Ceti 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 ofMOSTmonitoring 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.