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

Version 2 2024-06-05, 01:38
Version 1 2018-11-02, 15:12
journal contribution
posted on 2012-03-01, 00:00 authored by H M Cegla, C A Watson, T R Marsh, Sergiy ShelyagSergiy Shelyag, V Moulds, S Littlefair, M Mathioudakis, D Pollacco, X Bonfils
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.

History

Journal

Monthly notices of the Royal Astronomical Society: letters

Volume

421

Issue

1

Pagination

L54 - L58

Publisher

Oxford University Press

Location

Oxford, Eng.

ISSN

1745-3933

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2012, The Authors