A multiwavelength radial velocity search for planets around the brown dwarf LP 944-20

Abstract

The nearby brown dwarf LP 944-20 has been monitored for radial velocity variability at optical and near-infrared wavelengths using the VLT/UVES and the Keck/NIRSPEC spectrographs, respectively. The UVES radial velocity data obtained over 14 nights spanning a baseline of 841 days shows significant variability with an amplitude of 3.5 km s${}^{-1}$. The periodogram analysis of the UVES data indicates a possible period between 2.5 hours and 3.7 hours, which is likely due to the rotation of the brown dwarf. However, the NIRSPEC data obtained over 6 nights shows an rms dispersion of only 0.36 km s${}^{-1}$ and do not follow the periodic trend. These results indicate that the variability seen with UVES is likely to be due to rotationally modulated inhomogeneous surface features. We suggest that future planet searches around very low-mass stars and brown dwarfs using radial velocities will be better conducted in the near-infrared than in the optical.

accepted by ApJ Letters

References in corpus (1)

• Magnetic field generation in fully convective rotating spheres

Cited by in corpus (18)

• Doppler Imaging of Exoplanets and Brown Dwarfs
• Space Velocities of L- and T-type Dwarfs
• Multiepoch Radial Velocity Observations of L Dwarfs
• An Ultracool Star's Candidate Planet
• The HADES RV Programme with HARPS-N@TNG II. Data treatment and simulations
• WISE J072003.20-084651.2: An Old and Active M9.5 + T5 Spectral Binary 6 pc from the Sun
• Radial velocity photon limits for the dwarf stars of spectral classes F--M
• Lithium in LP 944-20
• Are isolated planetary-mass objects really isolated? A brown dwarf-exoplanet system candidate in the sigma Orionis cluster
• A Pathfinder Instrument for Precision Radial Velocities in the Near-Infrared
• Optical and near-infrared stellar activity characterization of the early M dwarf Gl~205 with SOPHIE and SPIRou
• On the radial velocity detection of additional planets in transiting, slowly rotating M-dwarf systems: the case of GJ 1132
• Spectral analysis of high resolution near-infrared spectra of ultra cool dwarfs
• DE0823$-$49 is a juvenile binary brown dwarf at 20.7 pc
• The photometric periods of rapidly rotating field ultra-cool dwarfs
• Empirical Determination of the Lithium 6707.856 Å Wavelength in Young Stars
• Gl 725A b: a potential super-Earth detected with SOPHIE and SPIRou in an M dwarf binary system at 3.5 pc
• Short-term spectroscopic monitoring of two cool dwarfs with strong magnetic fields