Stellar jitter from variable gravitational redshift: implications for radial velocity confirmation of habitable exoplanets

Cegla, Heather M., Watson, Christopher, Marsh, Tom, Shelyag, Sergiy, Moulds, Victoria, Littlefair, Stuart, Mathioudakis, Mihalis, Pollacco, Don and Bonfils, Xavier (2012) Stellar jitter from variable gravitational redshift: implications for radial velocity confirmation of habitable exoplanets. Monthly notices of the Royal Astronomical Society: Letters, 421 (1). L54-L58. ISSN 1745-3925

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Official URL: http://dx.doi.org/10.1111/j.1745-3933.2011.01205.x

Abstract

A variation of gravitational redshift, arising from stellar radius fluctuations, will introduce astrophysical noise into radial velocity measurements by shifting the centroid of the observed spectral lines. Shifting the centroid does not necessarily introduce line asymmetries. This is fundamentally different from other types of stellar jitter so far identified, which do result from line asymmetries. Furthermore, only a very small change in stellar radius, ∼0.01 per cent, is necessary to generate a gravitational redshift variation large enough to mask or mimic an Earth-twin. We explore possible mechanisms for stellar radius fluctuations in low-mass stars. Convective inhibition due to varying magnetic field strengths and the Wilson depression of starspots are both found to induce substantial gravitational redshift variations. Finally, we investigate a possible method for monitoring/correcting this newly identified potential source of jitter and comment on its impact for future exoplanet searches.

Item Type: Article
Uncontrolled Keywords: techniques: radial velocities, stars: activity, stars: late‐type, planetary systems
Subjects: F300 Physics
F500 Astronomy
G100 Mathematics
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Sergiy Shelyag
Date Deposited: 23 May 2016 10:27
Last Modified: 09 May 2017 05:48
URI: http://nrl.northumbria.ac.uk/id/eprint/26900

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