An active M8.5 dwarf wide companion to the M4/DA binary LHS4039/LHS4040

Abstract

Low-mass and brown dwarfs have recently been found as wide companions to many nearby stars, formerly believed to be single. Wide binaries are usually found as common proper motion pairs. Sometimes, more than two objects share the same large proper motion, identifying them as nearby systems. We have found a third, low-mass component to a known wide binary at a distance of about 21pc, consisting of a red and a white dwarf (LHS4039 and LHS4040; about 150AU separation). The new companion, APMPMJ2354-3316C separated by about 2200AU, was classified as M8.5 dwarf. In recent spectroscopic observations it shows a very strong $H_{\alpha }$ emission line and blue continuum. Comparing this event to flares in late-type M dwarfs, we find some similarity with LHS2397a, a nearby M8 dwarf which is so far the only known example of a low-mass star with a tight brown dwarf companion (separation of less than 4AU). The level of the activity as measured by $L_{H_{\alpha }}/L_{bol}$ is comparable to that of the M9.5 dwarf 2MASSWJ0149+29 both during the flare and in quiescence.

arXiv comment6 pages, 3 figures, accepted for publication in MNRAS, Figures 1 and 2 available as finding_chart.jpg and 2mass_k.jpg

References in corpus (23)

• Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs
• The SuperCOSMOS Sky Survey. Paper I: Introduction and Description
• New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence
• Brown Dwarf Companions to G-type Stars. I: Gliese 417B and Gliese 584C
• Discovery of a Brown Dwarf Companion to Gliese 570ABC: A 2MASS T Dwarf Significantly Cooler than Gliese 229B
• The SuperCOSMOS Sky Survey. Paper II: Image detection, parameterisation, classification and photometry
• The SuperCOSMOS Sky Survey. Paper III: Astrometry
• Epsilon Indi B: a new benchmark T dwarf
• Three Wide-Separation L dwarf Companions from the Two Micron All Sky Survey: Gl 337C, Gl 618.1B, and HD 89744B
• Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalogue
• The census of cataclysmic variables in the ROSAT Bright Survey
• Discovery of a Tight Brown Dwarf Companion to the Low Mass Star LHS 2397a
• A 2MASS L Dwarf Companion to the Nearby K Dwarf GJ 1048
• Discovery of a very cool object with extraordinarily strong H(alpha) emission
• The Liverpool-Edinburgh High Proper Motion Survey
• A Distant Stellar Companion in the Upsilon Andromedae System
• SSSPMJ0829-1309: A new nearby L dwarf detected in SuperCOSMOS Sky Surveys
• A new wide pair of cool white dwarfs in the Solar neighbourhood
• New nearby stars selected in a high proper motion survey by DENIS photometry
• A Near-Infrared Wide-Field Proper Motion Search for Brown Dwarfs
• Discovery of three nearby L dwarfs in the Southern Sky
• Three newly-discovered M-dwarf companions of Solar Neighbourhood stars
• New distant companions to known nearby stars: I. GJ 4047B, GJ 718B, GJ 747.2C, GJ 4100B, and GJ 4153B

Cited by in corpus (17)

• First Results from the Catalina Real-time Transient Survey
• The Hawaii Infrared Parallax Program. I. Ultracool Binaries and the L/T Transition
• Fundamental Parameters and Spectral Energy Distributions of Young and Field Age Objects with Masses Spanning the Stellar to Planetary Regime
• Low Luminosity Companions to White Dwarfs
• The binarity of the local white dwarf population
• The Solar Neighborhood XXXII. The Hydrogen Burning Limit
• The evolution of stellar triples: The most common evolutionary pathways
• Resolved Spectroscopy of M Dwarf/L Dwarf Binaries. I. DENIS J220002.05-303832.9AB
• The Solar Neighborhood. XXI. Parallax Results from the CTIOPI 0.9m Program: 20 New Members of the 25 Parsec White Dwarf Sample
• Wide, Cool and Ultracool Companions to Nearby Stars from Pan-STARRS1
• Spectroscopic classification of red high proper motion objects in the Southern Sky
• The Ultracool SpeXtroscopic Survey. I. Volume-Limited Spectroscopic Sample and Luminosity Function of M7$-$L5 Ultracool Dwarfs
• X-ray emission of brown dwarfs: Towards constraining the dependence on age, luminosity, and temperature
• Parallax and Luminosity Measurements of an L Subdwarf
• Quiescent X-ray emission from an evolved brown dwarf ?
• Discovery of a widely separated UCD-WD binary
• The Brown Dwarf Kinematics Project (BDKP). II. Details on Nine Wide Common Proper Motion Very Low-Mass Companions to Nearby Stars