Astrometric planet search around southern ultracool dwarfs

Lazorenko, P. F.; Ségransan, D.; Martín, E. L.; Mayor, M.; Queloz, D.; Udry, S.

doi:10.1051/0004-6361/201525757

Cited by 17 publications

(8 citation statements)

References 12 publications

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“…but there have also been a smaller number of mass measurements from radial velocity (RV; Basri & Martín 1999;Guenther & Wuchterl 2003;Joergens & Müller 2007;Blake et al 2008;Blake, Charbonneau & White 2010;Joergens, Müller & Reffert 2010;Burgasser et al 2010Burgasser et al , 2012bBurgasser et al , 2016aKonopacky et al 2010) and astrometric orbits (Sahlmann et al 2015(Sahlmann et al , 2013Koren et al 2016), as well as microlensing masses (e.g. Bennett et al 2008;Han et al 2013;Poleski et al 2017;Miyazaki et al 2018).…”

mentioning

confidence: 99%

Astrometric orbits of spectral binary brown dwarfs – I. Massive T dwarf companions to 2M1059−21 and 2M0805+48

Burgasser

Gagliuffi

Lazorenko

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Near-infrared spectroscopic surveys have uncovered a population of short-period, blended-light spectral binaries composed of low-mass stars and brown dwarfs. These systems are amenable to orbit determination and individual mass measurements via astrometric monitoring. Here, we present first results of a multiyear campaign to obtain high-precision absolute astrometry for spectral binaries using the Gemini-South and Gemini-North GMOS imagers. We measure the complete astrometric orbits for two systems: 2M0805+48 and 2M1059−21. Our astrometric orbit of 2M0805+48 is consistent with its 2-yr radial velocity orbit determined previously and we find a mass of $66^{+5}_{-14} M_\mathrm{Jup}$ for its T5.5 companion. For 2M1059−21, we find a 1.9-yr orbital period and a mass of $67^{+4}_{-5} M_\mathrm{Jup}$ for its T3.5 companion. We demonstrate that sub-milliarcsecond absolute astrometry can be obtained with both GMOS imagers and that this is an efficient avenue for confirming and characterizing ultracool binary systems.

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mentioning

confidence: 99%

Astrometric orbits of spectral binary brown dwarfs – I. Massive T dwarf companions to 2M1059−21 and 2M0805+48

Burgasser

Gagliuffi

Lazorenko

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Despite the low masses in the system, we do not find signs of lithium absorption in our UVES spectrum (Sahlmann et al 2015a). We could place an upper limit of ∼1Å on the Li I equivalent width (pEW) by visual inspection of simulations that consisted of injecting a spectral signature in the observed spectrum.…”

Section: Lithiummentioning

confidence: 75%

“…We used the astrometric and orbital parameters from Sahlmann et al (2015a) and reasonable guesses for the component masses and systemic radial velocity as starting values for a Markov Chain Monte Carlo (MCMC) analysis similar to that described in Sahlmann et al (2020). We used the emcee package (Foreman-Mackey et al 2013) to implement the MCMC and expressed the binary model using pystrometry (Sahlmann 2019) 1 with the parameter vector θ composed of ∆α 0 , ∆δ0, , µα , µ δ , ρ, d, P , e, ω, TP , sα, s δ , M1, M2, i and Ω, γ.…”

Section: Mcmc Analysismentioning

confidence: 99%

“…It is part of a long-term astrometric monitoring campaign that makes use of the FORS2 optical camera mounted on the Very Large Telescope (Sahlmann et al 2014). The discovery and characterisation of the binary orbit with an orbital period of 3.067±0.006 years is described in Sahlmann et al (2015a). Its proximity (∼20 pc) and expected orbital separation should make it possible to resolve the components with infrared (IR) adaptive optics (AO) facilities on 10m-class telescopes.…”

Section: Introductionmentioning

confidence: 99%

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Individual dynamical masses of DENIS J063001.4−184014AB reveal a likely young brown dwarf triple

Dupuy

Burgasser

Filippazzo

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The binary nature of the M8.5 dwarf DENIS J063001.4−184014AB (DE0630−18) was discovered with astrometric monitoring from the ground, which determined the unresolved photocentric orbit and the trigonometric parallax of the system. Here we present radial-velocity monitoring and resolved observations in the near-infrared with Keck aperture masking that allow us to measure the system’s relative separation and brightness. By combining all available information, we determine the individual dynamical masses of the binary components to be $M_1 = 0.052^{+0.009}_{-0.008}$ MSun and $M_2 = 0.052^{+0.005}_{-0.004}$ MSun, both firmly in the substellar regime. These masses are surprising given the object’s M8.5 optical spectral type and equivalent absolute magnitude, and the significant difference in brightness between the components (ΔK = 1.74±0.06 mag). Our results suggest that DE0630−18 is a relatively young system (∼200 Myr) with a secondary component that is itself a potentially unresolved binary.

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“…Two of those objects were found to be binaries. Here we focus on DENIS J063001.4−184014AB (hereafter Sahlmann 2 AB, inspired by the Washington Double Star catalog convention of naming objects after the discoverer of the binary nature), which was classified as an M8.5 dwarf from optical low-resolution reconnaissance spectroscopy and it was found to be an astrometric binary with an orbital period of 3.1 years (Sahlmann et al 2015a). The dynamical mass of each component in the binary has been obtained from combining the astrometric data with spatially resolved near-infrared imaging, and radial velocities for the primary (Sahlmann et al 2021).…”

Section: Martín Lodieu and Del Burgomentioning

confidence: 99%

New constraints on the minimum mass for thermonuclear lithium burning in brown dwarfs

Martín,

Lodieu,

del Burgo

2021

Preprint

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The theory of substellar evolution predicts that there is a sharp mass boundary between lithium and non-lithium brown dwarfs, not far below the substellar-mass limit. The imprint of thermonuclear burning is carved on the surface lithium abundance of substellar-mass objects during the first few hundred million years of their evolution, leading to a sharp boundary between lithium and non-lithium brown dwarfs, so-called, the lithium test. The theoretical predictions can be tested by comparing with observations of lithium in the individual components of binaries with dynamical masses measured from orbital motions. New optical spectroscopic observations of the binaries DE-NIS J063001.4−184014AB and DENIS J225210.7−173013AB obtained using the 10.4-m Gran Telescopio de Canarias are reported here. They allow us to re-determine their combined optical spectral types (M9.5 and L6.5, respectively) and to search for the presence of the Li I resonance doublet. The non detection of the Li I feature in the combined spectrum of DENIS J063001.4−184014AB is converted into estimates for the depletion of lithium in the individual components of this binary system. In DENIS J225210.7−173013AB we report the detection of a weak Li I feature which we tentatively ascribe as arising from the contribution of the T3.5-type secondary. Combining our results with data for seven other brown dwarf binaries in the literature treated in a self-consistent way, we confirm that there is indeed a sharp transition in mass for lithium depletion in brown dwarfs, as expected from theoretical calculations. We estimate such mass boundary is observationally located at 51.48 +0.22 −4.00 M Jup , which is lower than the theoretical determinations.

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Astrometric planet search around southern ultracool dwarfs

Cited by 17 publications

References 12 publications

Astrometric orbits of spectral binary brown dwarfs – I. Massive T dwarf companions to 2M1059−21 and 2M0805+48

Astrometric orbits of spectral binary brown dwarfs – I. Massive T dwarf companions to 2M1059−21 and 2M0805+48

Individual dynamical masses of DENIS J063001.4−184014AB reveal a likely young brown dwarf triple

New constraints on the minimum mass for thermonuclear lithium burning in brown dwarfs

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