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Stellar jitter from variable gravitational redshift: implications for radial velocity confirmation of habitable exoplanets
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 BonfilsA 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: lettersVolume
421Issue
1Pagination
L54 - L58Publisher
Oxford University PressLocation
Oxford, Eng.Publisher DOI
ISSN
1745-3933Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2012, The AuthorsUsage metrics
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