The mass-luminosity relation in the L/T transition: Individual dynamical masses for the new J-band flux reversal binary SDSS J105213.51+442255.7AB

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dc.contributor.authorDupuy, Trenten_AU
dc.contributor.authorLiu, Michael Cen_AU
dc.contributor.authorLeggett, S Ken_AU
dc.contributor.authorChiu, Kuenleyen_AU
dc.contributor.authorGolimowski, David Aen_AU
dc.contributor.authorIreland, Michaelen_AU
dc.date.accessioned2016-06-14T23:20:07Z
dc.date.issued2015
dc.date.updated2016-06-14T08:45:50Z
dc.description.abstractWe have discovered that SDSS J105213.51+442255.7 (T0.5 ± 1.0) is a binary in Keck laser guide star adaptive optics imaging, displaying a large J- to K-band flux reversal (mag, mag). We determine a total dynamical mass from Keck orbital monitoring (88 ± 5) and a mass ratio by measuring the photocenter orbit from CFHT/WIRCam absolute astrometry (). Combining these provides the first individual dynamical masses for any field L or T dwarfs, 49 ± 3 for the L6.5±1.5 primary and 39 ± 3 for the T1.5±1.0 secondary. Such a low mass ratio for a nearly equal luminosity binary implies a shallow mass-luminosity relation over the L/T transition (). This provides the first observational support that cloud dispersal plays a significant role in the luminosity evolution of substellar objects. Fully cloudy models fail our coevality test for this binary, giving ages for the two components that disagree by 0.2 dex (2.0σ). In contrast, our observed masses and luminosities can be reproduced at a single age by "hybrid" evolutionary tracks where a smooth change from a cloudy to cloudless photosphere around 1300 K causes slowing of luminosity evolution. Remarkably, such models also match our observed JHK flux ratios and colors well. Overall, it seems that the distinguishing features SDSS J1052+4422AB, like a J-band flux reversal and high-amplitude variability, are normal for a field L/T binary caught during the process of cloud dispersal, given that the age ( Gyr) and surface gravity ( = 5.0-5.2) of SDSS J1052+4422AB are typical for field ultracool dwarfs.
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1885/103213
dc.publisherIOP Publishing
dc.rightsAuthor/s retain copyrighten_AU
dc.sourceAstrophysical Journal, The
dc.titleThe mass-luminosity relation in the L/T transition: Individual dynamical masses for the new J-band flux reversal binary SDSS J105213.51+442255.7AB
dc.typeJournal article
dcterms.accessRightsOpen Accessen_AU
local.bibliographicCitation.issue1
local.contributor.affiliationDupuy, Trent, University of Texas at Austin
local.contributor.affiliationLiu, Michael C, University of Hawaii
local.contributor.affiliationLeggett, S K, Gemini Observatory
local.contributor.affiliationIreland, Michael, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationChiu, Kuenley, C3 Energy
local.contributor.affiliationGolimowski, David A, Space Telescope Science Institute
local.contributor.authoremailu5544212@anu.edu.au
local.contributor.authoruidIreland, Michael, u5544212
local.description.notesImported from ARIES
local.identifier.absfor020102 - Astronomical and Space Instrumentation
local.identifier.absfor020104 - Galactic Astronomy
local.identifier.absfor020110 - Stellar Astronomy and Planetary Systems
local.identifier.absseo970102 - Expanding Knowledge in the Physical Sciences
local.identifier.ariespublicationU3488905xPUB5652
local.identifier.citationvolume805
local.identifier.doi10.1088/0004-637X/805/1/56
local.identifier.scopusID2-s2.0-84930000588
local.identifier.uidSubmittedByU3488905
local.type.statusPublished Version

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