M dwarf search for pulsations within Kepler Guest Observer programme

• Published in: Monthly notices of the Royal Astronomical Society Vol. 446; no. 3; p. 2613
• Main Authors: Rodriguez-Lopez, C, Gizis, J E, MacDonald, J, Amado, P J, Carosso, A
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 21-01-2015
• Subjects: Amplitudes; Astronomy; Dwarf stars; Instability; Kepler mission (NASA); Observers; Oscillations; Photometry; Pulsars; Pulsation; Sampling; Searching; Spectrum analysis
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stu2211

We present the analysis of four M dwarf stars -- plus one M giant that seeped past our selection criteria -- observed in Cycle 3 of Kepler Guest Observer programme (GO3) in a search for intrinsic pulsations. Stellar oscillations in M dwarfs were theoretically predicted by Rodriguez-Lopez et al. to be in the range similar to 20-40 min and similar to 4-8 h, depending on the age and the excitation mechanism. We requested Kepler short cadence observations to have an adequate sampling of the oscillations. The targets were chosen on the basis of detectable rotation in the initial Kepler results, biasing towards youth. The analysis reveals no oscillations attributable to pulsations at a detection limit of several parts per million, showing that either the driving mechanisms are not efficient in developing the oscillations to observable amplitudes, or that if pulsations are driven, the amplitudes are very low. The size of the sample, and the possibility that the instability strip is not pure, allowing the coexistence of pulsators and non-pulsators, prevent us from deriving definite conclusions. Immediate plans include more M dwarfs photometric observations of similar precision with Kepler K2 mission and spectroscopic searches already underway within the Cool Tiny Beats Project with the high-resolution spectrographs HARPS and HARPS-N.