Multiepoch radial velocity observations of L dwarfs

Cullen H. Blake, David Charbonneau, Russel J. White, Mark S. Marley, Didier Saumon

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


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 μm of nine L dwarfs taken with the Phoenix instrument on Gemini South and demonstrate a typical precision of 300 m s-1. We conduct simulations to estimate our expected precision and show that our performance is currently limited by the signal-to-noise ratio (S/N) 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 > 2 M J in orbits with periods less than 3 days. We identify no companions in our current data set. Future observations with improved S/N should result in radial velocity precision of 100 m s-1 for L dwarfs.

Original languageEnglish (US)
Pages (from-to)1198-1204
Number of pages7
JournalAstrophysical Journal
Issue number2 I
StatePublished - 2007
Externally publishedYes


  • Planetary systems
  • Stars: low-mass, brown dwarfs
  • Techniques: radial velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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