Radial and rotational velocities of young brown dwarfs and very low-mass stars in the Upper Scorpius OB association and the Ophiuchi cloud core

2006/09/02 by Ryuichi Kurosawa, Tim J. Harries, S. P. Littlefair · 4 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Brown dwarf #Galaxy #Low Mass #Physics #Radial velocity #Spectral line #Spectrograph #Stars #Stellar, planetary, and galactic studies #Telescope #Velocity dispersion #Very Large Telescope #astro-ph

paper · pdf · doi:10.1111/j.1365-2966.2006.11005.x

published as Mon.Not.Roy.Astron.Soc.372:1879-1887,2006 · 10 pages, 5 figures, accepted for publication in MNRAS

arxiv created 2006/09/02 · openalex publication_date 2006/10/14 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We present the results of a radial velocity (RV) survey of 14 brown dwarfs (BDs) and very low-mass (VLM) stars in the Upper Scorpius OB association (UScoOB) and three BD candidates in the ρ Ophiuchi dark cloud core. We obtained high-resolution echelle spectra at the Very Large Telescope using the Ultraviolet and Visual Echelle Spectrograph (UVES) at two different epochs for each object, and measured the shifts in their RVs to identify candidates for binary/multiple systems in the sample. The average time separation of the RV measurements is 21.6 d, and our survey is sensitive to the binaries with separation <0.1 au. We found that four out of 17 objects (or 24+16−13 per cent by fraction) show a significant RV change in 4–33 d time-scale, and are considered as binary/multiple ‘candidates’. We found no double-lined spectroscopic binaries in our sample, based on the shape of cross-correlation curves. The RV dispersion of the objects in UScoOB is found to be very similar to that of the BD and VLM stars in Chamaeleon I (Cha I). We also found the distribution of the mean rotational velocities (v sin i) of the UScoOB objects is similar to that of the Cha I, but the dispersion of v sin i is much larger than that of the Cha I objects.

Citations

• Photometry of Proxima Centauri and Barnard's Star Using [ITAL]Hubble[/ITAL] [ITAL]Space[/ITAL] [ITAL]T[/ITAL][ITAL]elescope[/ITAL] Fine Guidance Sensor 3: A Search for Periodic Variations
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• Spectroscopy of Brown Dwarf Candidates in the ρ Ophiuchi Molecular Core
• Accretion in Young Stellar/Substellar Objects
• The First Discovery of a Wide Binary Brown Dwarf
• Pulsating young brown dwarfs
• An optimal extraction algorithm for CCD spectroscopy
• The Formation of Brown Dwarfs as Ejected Stellar Embryos
• First radius measurements of very low mass stars with the VLTI
• The T Tauri Phase Down to Nearly Planetary Masses: Echelle Spectra of 82 Very Low Mass Stars and Brown Dwarfs
• AHubble Space TelescopeWide Field Planetary Camera 2 Survey for Brown Dwarf Binaries in the α Persei and Pleiades Open Clusters
• Detection of Nine M8.0–L0.5 Binaries: The Very Low Mass Binary Population and Its Implications for Brown Dwarf and Very Low Mass Star Formation
• A [ITAL]Hipparcos[/ITAL] Census of the Nearby OB Associations
• Spectroscopic rotation velocities of L dwarfs from VLT/UVES and their comparison with periods from photometric monitoring
• The Formation of Free-Floating Brown Dwarves and Planetary-Mass Objects by Photo-Erosion of Prestellar Cores

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