Multiepoch Radial Velocity Observations of L Dwarfs

Abstract

We report on the development of a technique for precise radial-velocity measurements of cool stars and brown dwarfs in the near infrared. Our technique is analogous to the Iodine (I2) absorption cell method that has proven so successful in the optical regime. We rely on telluric CH4 absorption features to serve as a wavelength reference, relative to which we measure Doppler shifts of the CO and H2O features in the spectra of our targets. We apply this technique to high-resolution (R~50,000) spectra near 2.3 micron of nine L dwarfs taken with the Phoenix instrument on Gemini-South and demonstrate a typical precision of 300 m/s. We conduct simulations to estimate our expected precision and show our performance is currently limited by the signal-to-noise of our data. We present estimates of the rotational velocities and systemic velocities of our targets. With our current data, we are sensitive to companions with M sin i > 2MJ in orbits with periods less than three days. We identify no companions in our current data set. Future observations with improved signal-to-noise should result in radial-velocity precision of 100 m/s for L dwarfs.

Accepted for publication in ApJ, 24 pages, 7 figures

References in corpus (8)

• Detection of Thermal Emission from an Extrasolar Planet
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• Microlens OGLE-2005-BLG-169 Implies Cool Neptune-Like Planets are Common
• Exploring The Frequency Of Close-In Jovian Planets Around M Dwarfs
• Strong Infrared Emission from the Extrasolar Planet HD189733b
• Activity and Kinematics of Ultracool Dwarfs Including An Amazing Flare Observation
• A multiwavelength radial velocity search for planets around the brown dwarf LP 944-20
• Rapid Formation of Super-Earths around M Dwarf Stars

Cited by in corpus (17)

• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Young L Dwarfs Identified in the Field: A Preliminary Low-Gravity, Optical Spectral Sequence from L0 to L5
• Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839-0446358
• Doppler Imaging of Exoplanets and Brown Dwarfs
• IN-SYNC I: Homogeneous Stellar Parameters from High Resolution APOGEE Spectra for Thousands of Pre-main Sequence Star
• A Young Planet Search in Visible and IR Light: DN Tau, V836 Tau, and V827 Tau
• Near Infrared Monitoring of Ultracool Dwarfs: Prospects for Searching for Transiting Companions
• Trigonometric parallaxes of young field L dwarfs
• ACRONYM III: Radial Velocities for 336 Candidate Young Low-Mass Stars in the Solar Neighborhood, Including 78 Newly Confirmed Young Moving Group Members
• A Spectroscopic Binary at the M/L Transition
• The MEarth project: searching for transiting habitable super-Earths around nearby M-dwarfs
• The 3-D Kinematics of the Orion Nebula Cluster: NIRSPEC-AO Radial Velocities of the Core Population
• Individual, Model-Independent Masses of the Closest Known Brown Dwarf Binary to the Sun
• A Pathfinder Instrument for Precision Radial Velocities in the Near-Infrared
• An Age Constraint for the Very Low-Mass Stellar/Brown Dwarf Binary 2MASS J03202839-0446358AB
• The 3D Kinematics of the Orion Nebula Cluster II: Mass-dependent Kinematics of the Inner Cluster
• The Brown Dwarf Kinematics Project (BDKP). V. Radial and Rotational Velocities of T Dwarfs from Keck/NIRSPEC High-Resolution Spectroscopy