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arxiv 0909.0002 v2 pith:YTNTR7US submitted 2009-08-31 astro-ph.SR astro-ph.EP

Detecting Planets Around Very Low Mass Stars with the Radial Velocity Method

classification astro-ph.SR astro-ph.EP
keywords starsopticalradialvelocitymeasurementsprecisionspotwavelengths
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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The detection of planets around very low-mass stars with the radial velocity method is hampered by the fact that these stars are very faint at optical wavelengths where the most high-precision spectrometers operate. We investigate the precision that can be achieved in radial velocity measurements of low mass stars in the near infrared (nIR) Y-, J-, and H-bands, and we compare it to the precision achievable in the optical. For early-M stars, radial velocity measurements in the nIR offer no or only marginal advantage in comparison to optical measurements. Although they emit more flux in the nIR, the richness of spectral features in the optical outweighs the flux difference. We find that nIR measurement can be as precise than optical measurements in stars of spectral type ~M4, and from there the nIR gains in precision towards cooler objects. We studied potential calibration strategies in the nIR finding that a stable spectrograph with a ThAr calibration can offer enough wavelength stability for m/s precision. Furthermore, we simulate the wavelength-dependent influence of activity (cool spots) on radial velocity measurements from optical to nIR wavelengths. Our spot simulations reveal that the radial velocity jitter does not decrease as dramatically towards longer wavelengths as often thought. The jitter strongly depends on the details of the spots, i.e., on spot temperature and the spectral appearance of the spot. Forthcoming nIR spectrographs will allow the search for planets with a particular advantage in mid- and late-M stars. Activity will remain an issue, but simultaneous observations at optical and nIR wavelengths can provide strong constraints on spot properties in active stars.

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Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. RedDots: Magnetic field of the nearby active M dwarf GJ 729, and a search for companions

    astro-ph.SR 2026-07 conditional novelty 4.0

    GJ 729 exhibits a weak, evolving large-scale magnetic field (50-145 G) and a persistent ~7 d radial velocity signal that could be a ~1.5-2 Earth-mass planet or residual stellar activity.