J/AJ/163/288ivo://CDS.VizieR/J/AJ/163/288doi:10.26093/cds/vizier.51630288CDSChen M.Li Y.Brandt T.D.Dupuy T.J.Cardoso C.V.McCaughrean M.J.2024-02-13T12:07:35Z2022-10-21T07:22:23ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frexoplanetsmultiple-starsdwarf-starsastrometryinfrared-photometryWe report individual dynamical masses of 66.92{+/-}0.36 MJup and 53.25{+/-}0.29MJup for the binary brown dwarfs {epsilon} Indi Ba and Bb, measured from long-term (~10yr) relative orbit monitoring and absolute astrometry monitoring data on the Very Large Telescope (VLT). Relative astrometry with NACO fully constrains the Keplerian orbit of the binary pair, while absolute astrometry with FORS2 measures the system's parallax and mass ratio. We find a parallax consistent with the Hipparcos and Gaia values for {epsilon} Indi A, and a mass ratio for {epsilon} Indi Ba to Bb precise to better than 0.2%. {epsilon} Indi Ba and Bb have spectral types T1-1.5 and T6, respectively. With an age of 3.5_-1.0_^+0.8^Gyr from {epsilon} Indi A's activity, these brown dwarfs provide some of the most precise benchmarks for substellar cooling models. Assuming coevality, the very different luminosities of the two brown dwarfs and our moderate mass ratio imply a steep mass-luminosity relationship (L{prop}M^5.37{+/-}0.08^) that can be explained by a slowed cooling rate in the L/T transition, as previously observed for other L/T binaries. Finally, we present a periodogram analysis of the near-infrared photometric data, but find no definitive evidence of periodic signals with a coherent phase.2022AJ....163..288Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/163/288CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/pastel : The PASTEL catalogue (Soubiran+, 2016-)IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)I/259 : The Tycho-2 Catalogue (Hog+ 2000)I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/348/897 : Ages of main-sequence stars (Lachaume+, 1999)J/AJ/132/161 : NStars project; The southern sample. I. (Gray+, 2006)J/A+A/509/A52 : Search for companions with VLT/NACO (Chauvin+, 2010)J/A+A/510/A99 : Epsilon Indi Ba and Bb IR spectra (King+, 2010)J/A+A/512/A37 : Velocities of 43 nearby L dwarfs (Seifahrt+, 2010)J/MNRAS/428/2824 : Rapid optical variability in ultracool dwarfs (Koen, 2013)J/A+A/551/L8 : Chromospheric activity of field stars (Pace, 2013)J/A+A/552/A78 : Solar like stars radial velocities (Zechmeister+, 2013)J/AJ/147/94 : Solar neighborhood. XXXII. L and M dwarfs (Dieterich+, 2014)J/ApJS/231/15 : Astrometric monitoring ultracool dwarf binaries (Dupuy+, 2017)J/ApJ/837/30 : 25yrs monitoring of stellar orbits in the GC (Gillessen+, 2017)J/ApJ/842/118 : Brown dwarfs with spectral type later than T6 (Leggett+, 2017)J/A+A/615/A76 : Spectroscopic parameters of stars (SPECIES). I. (Soto+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/163/288https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/163/288http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/163/288https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/163/288https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/163/288http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/163/288GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/AJ/163/288/table2Absolute astrometry data from FORS2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs[2005/2016] Astrometry date, yeartime.epochNframes[1/30] Number of framesmeta.numberintBand[I] Bandinstr.bandpasscharTexp[20/600] Total integrationstimeintJ/AJ/163/288/table3Relative astrometry resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpoch[2004/2014] Epoch, Besslian fractional yearyrtime.epoch;arith.ratiodoubleSep[0.14/0.95] Separationarcsecpos.angDistance;src.orbitaldoublee_Sep[0.001/0.003] Uncertainty in Separcsecstat.errordoublePA[12.9/340] Position angle, east of northdegpos.posAngfloate_PA[0.04/0.6] Uncertainty in PAdegstat.errorfloat