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

Heather Cegla, Christopher Watson, T.R. Marsh, Sergiy Shelyag, Victoria Moulds, S. Littlefair, Michail Mathioudakis, Don Pollacco, X. Bonfils

Research output: Contribution to journalLetter

12 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)L54-L58
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Volume421
Issue number1
DOIs
Publication statusPublished - Mar 2012

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