RESOLVED SPECTROSCOPY OF M DWARF/L DWARF BINARIES. IV. DISCOVERY OF AN M9 + L6 BINARY SEPARATED BY OVER 100 AU

2010/10/11 by Saurav Dhital, Adam J. Burgasser, Dagny L. Looper +1
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Binary number #Brown dwarf #Infrared #Mass ratio #Physics #Proper motion #Sky #Spectroscopy #Stars #Stellar, planetary, and galactic studies #Telescope #astro-ph.SR

paper · pdf · doi:10.1088/0004-6256/141/1/7

Accepted by the AJ (8 pages, emulateapj format)

arxiv created 2010/10/11 · openalex publication_date 2010/12/07 · arxiv updated 2012/02/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

We report the discovery of a faint L6 ± 1 companion to the previously known M9 dwarf, 2MASS J01303563−4445411, based on our near-infrared imaging and spectroscopic observations with the 3 m Infrared Telescope Facility SpeX imager/spectrometer. The visual binary is separated by 3 28 ± 0 05 on the sky at a spectrophotometric distance of 40 ± 14 pc. The projected physical separation is 130 ± 50 AU, making it one of the widest very low mass (VLM) field multiples containing a brown dwarf companion. 2MASS J0130−4445 is only one of ten wide VLM pairs and only one of six in the field. The secondary is considerably fainter (Δ K ≈ 2.35 mag) and redder (Δ ( J − K s ) ≈ 0.81 dex), consistent with component near-infrared types of M9.0 ± 0.5 and L6 ± 1 based on our resolved spectroscopy. The component types suggest a secondary mass well below the hydrogen-burning limit and an age-dependent mass ratio of 0.6–0.9. The system's space motion and spectroscopic indicators suggest an age of 2–4 Gyr while the model-dependent masses and binding energies suggest that this system is unlikely to have formed via dynamical ejection. The age, composition, and separation of the 2MASS J01303563−4445411 system make it useful for tests of VLM formation theories and of condensate cloud formation in L dwarfs.

Citations

• An expanded set of brown dwarf and very low mass star models
• Stellar, brown dwarf and multiple star properties from hydrodynamical simulations of star cluster formation
• The First Direct Measurements of Surface Magnetic Fields on Very Low Mass Stars
• The Mauna Kea Observatories Near‐Infrared Filter Set. II. Specifications for a NewJHKL′M′ Filter Set for Infrared Astronomy
• The Formation of Brown Dwarfs as Ejected Stellar Embryos
• The Evolution of L and T Dwarfs in Color‐Magnitude Diagrams
• Spextool: A Spectral Extraction Package for SpeX, a 0.8–5.5 Micron Cross‐Dispersed Spectrograph
• Radio Observations of a Large Sample of Late M, L, and T Dwarfs: The Distribution of Magnetic Field Strengths
• SpeX: A Medium‐Resolution 0.8–5.5 Micron Spectrograph and Imager for the NASA Infrared Telescope Facility
• The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low‐Resolution Near‐Infrared Spectra
• A Method of Correcting Near‐Infrared Spectra for Telluric Absorption1
• Multiplicity among M dwarfs
• The Mauna Kea Observatories Near‐Infrared Filter Set. I. Defining Optimal 1–5 Micron Bandpasses
• 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 Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf “Lithium Test” at Early Ages
• Precipitating Condensation Clouds in Substellar Atmospheres
• New Spectral Types L and T
• Discovery of a T Dwarf Binary with the Largest KnownJ‐Band Flux Reversal
• The Two Micron All Sky Survey (2MASS)
• Subtle Signatures of Multiplicity in Late‐type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839−0446358
• The Formation of Free-Floating Brown Dwarves and Planetary-Mass Objects by Photo-Erosion of Prestellar Cores