Mass estimates for visual binaries with incomplete orbits

Lucy, L. B.

doi:10.1051/0004-6361/201322649

Cited by 40 publications

(49 citation statements)

References 18 publications

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“…For the relative orbit parameters, we performed a grid search over the parameters P , e, and T 0 . Once these three parameters are specified, then the eccentric anomaly can be computed and the best-fit orbit can be directly analytically determined, as described in detail by Lucy (2014). We searched across 10 4 randomly drawn values between 0 ≤ e < 1, 0 ≤ T 0 /P < 1, and log(P ) initially from 10 3 to 10 6 days.…”

Section: Joint Orbit and Parallax Analysismentioning

confidence: 99%

Individual Dynamical Masses of Ultracool Dwarfs* ^† ^‡

Dupuy

Liu

2017

ApJS

189

216

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We present the full results of our decade-long astrometric monitoring programs targeting 31 ultracool binaries with component spectral types M7-T5. Joint analysis of resolved imaging from Keck Observatory and Hubble Space Telescope and unresolved astrometry from CFHT/WIRCam yields parallactic distances for all systems, robust orbit determinations for 23 systems, and photocenter orbits for 19 systems. As a result, we measure 38 precise individual masses spanning 30-115 M Jup . We determine a modelindependent substellar boundary that is ≈70 M Jup in mass (≈L4 in spectral type), and we validate Baraffe et al. (2015) evolutionary model predictions for the lithium-depletion boundary (60 M Jup at field ages). Assuming each binary is coeval, we test models of the substellar mass-luminosity relation and that find in the L/T transition, only the Saumon & Marley (2008) "hybrid" models accounting for cloud clearing match our data. We derive a precise, mass-calibrated spectral type-effective temperature relation covering 1100-2800 K. Our masses enable a novel direct determination of the age distribution of field brown dwarfs spanning L4-T5 and 30-70 M Jup . We determine a median age of 1.3 Gyr, and our population synthesis modeling indicates our sample is consistent with a constant star formation history modulated by dynamical heating in the Galactic disk. We discover two triple-brown-dwarf systems, the first with directly measured masses and eccentricities. We examine the eccentricity distribution, carefully considering biases and completeness, and find that low-eccentricity orbits are significantly more common among ultracool binaries than solar-type binaries, possibly indicating the early influence of long-lived dissipative gas disks. Overall, this work represents a major advance in the empirical view of very low-mass stars and brown dwarfs.

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Section: Joint Orbit and Parallax Analysismentioning

confidence: 99%

Individual Dynamical Masses of Ultracool Dwarfs* ^† ^‡

Dupuy

Liu

2017

ApJS

189

216

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“…To estimate the orbits of the G objects, we use uniform priors on all eight fitted parameters (six orbital parameters and two systematic uncertainty parameters). While uniform priors are commonly assumed in orbit fitting, this choice has been shown to cause potential biases in estimated parameters when orbital periods are much longer than the time baseline of observations 39,40 . To assess the impact of our fitting procedure in this context, we ran simulations to assess possible biases in the estimated parameters and to test the accuracy of confidence intervals obtained in our analysis 40 .…”

Section: Dependence On Priorsmentioning

confidence: 99%

A population of dust-enshrouded objects orbiting the Galactic black hole

Ciurlo

Campbell

Morris

et al. 2020

Nature

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Nature volume 577, pages337-340 (2020) https://www.nature.com/articles/s41586-019-1883-yThe central 0.1 parsecs of the Milky Way host a supermassive black hole identified with the position of the radio and infrared source Sagittarius A* (refs 1,2 ), a cluster of young, massive stars (the S stars 3 ) and various gaseous features 4,5 . Recently, two unusual objects have been found to be closely orbiting Sagittarius A*: the so-called G sources, G1 and G2. These objects are unresolved (having a size on the order of 100 astronomical units, except at periapse where the tidal interaction with the black hole stretches them along the orbit) and they show both thermal dust emission and line emission from ionized gas 6-10 . G1 and G2 have generated attention because they appear to be tidally interacting with the supermassive Galactic black hole, possibly enhancing its accretion activity. No broad consensus has yet been reached concerning their nature: the G objects show the characteristics of gas and dust clouds but display the dynamical properties of stellar-mass objects. Here we report observations of four additional G objects, all lying within 0.04 parsecs of the black hole, and forming a class that is probably unique to this environment. The widely varying orbits derived for the six G objects demonstrate that they were commonly but separately formed.We used near-infrared (NIR) spectro-imaging data obtained over the past 13 years 11 at the W. M. Keck Observatory with the OSIRIS integral field spectrometer 12 , coupled with laser guide star adaptive optics wave front corrections 13 . OSIRIS data-cubes have two spatial dimensions -about 3 arcsec × 2 arcsec surrounding Sgr A* with a plate-scale of 35 mas-and one wavelength dimension -covering the Kn3 band, 2.121-2.229 µm, with a spectral resolution of R ≈ 3,800. We selected 24 datacubes based on image-quality and signal-to-noise ratio; see Methods section 'Observations'. These cubes were processed through the OSIRIS pipeline 14 . We also removed the stellar continua to isolate emission features associated with interstellar gas (Methods section 'Continuum subtraction'). The reduced data-cubes were analysed with a 3D visualization tool, OsrsVol 15 , that simultaneously displays all dimensions of the data-cube. This helps disentangle the many features of this crowded region, which are often superimposed in the spatial dimension but are separable in the wavelength dimension (Fig. 1).Analysing the data with OsrsVol as well as conventional 2D and 1D tools, we identify four new compact objects in Brackett-γ line emission (Brγ; 2.1661 µm rest wavelength) that consistently appear in the data across the observed timeline. In addition to Brγ, all four objects show two [Fe III] emission lines (at 2.1457 µm and 2.2184 µm; ref. 16 ).

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“…However exoplanets are not the only objects to perturb the positions of stars; it has also been suggested that precise astrometric observations also have the potential to detect and characterize otherwise unseen black hole (BH) and neutron star (NS) companions to main sequence stars (Gould & Salim 2002;Tomsick & Muterspaugh 2010;Barstow et al 2014). Pioneering studies with ground-based interferometry have proven that precise tracking of the sky position of stars can afford some of the best measurements of binary star orbits, particularly when combined with spectroscopic radial velocities (Hartkopf et al 1996;Mason et al 1999;Bowler et al 2018;Gardner et al 2018;Lucy 2018). Extensions to space-based observatories have so far been limited to a handful of binaries observed using the Hubble Space Telescope's Fine Guidance Sensor (Franz et al 1998;Hershey & Taff 1998;Benedict et al 2000) and with Hipparcos (Pourbaix & Jorissen 2000;Halbwachs et al 2000;Pourbaix & Boffin 2003;Goldin & Makarov 2007).…”

Section: Introductionmentioning

confidence: 99%

Weighing the Darkness: Astrometric Mass Measurement of Hidden Stellar Companions Using Gaia

Andrews

Breivik

Chatterjee³

2019

ApJ

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In astrometric binaries, the presence of a dark, unseen star can be inferred from the gravitational pull it induces on its luminous binary companion. While the orbit of such binaries can be characterized with precise astrometric measurements, constraints made from astrometry alone are not enough to measure the component masses. In this work, we determine the precision with which Gaia can astrometrically measure the orbits and -with additional observations -the component masses, for luminous stars hosting hidden companions. Using realistic mock Gaia observations, we find that Gaia can precisely measure the orbits of binaries hosting hidden brown-dwarfs out to tens of pc and hidden white dwarf and neutron star companions at distances as far as several hundred pc. Heavier black hole companions may be measured out to 1 kpc or farther. We further determine how orbital period affects this precision, finding that Gaia can characterize orbits with periods as short as 10 days and as long as a few 10 3 days, with the best measured orbits having periods just short of Gaia's mission lifetime. Extending Gaia's nominal five-year mission lifetime by an additional five years not only allows for the measurement of longer period orbits, but those longer period binaries can be seen at even greater distances.

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Mass estimates for visual binaries with incomplete orbits

Cited by 40 publications

References 18 publications

Individual Dynamical Masses of Ultracool Dwarfs* ^† ^‡

Individual Dynamical Masses of Ultracool Dwarfs* ^† ^‡

A population of dust-enshrouded objects orbiting the Galactic black hole

Weighing the Darkness: Astrometric Mass Measurement of Hidden Stellar Companions Using Gaia

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Mass estimates for visual binaries with incomplete orbits

Cited by 40 publications

References 18 publications

Individual Dynamical Masses of Ultracool Dwarfs* † ‡

Individual Dynamical Masses of Ultracool Dwarfs* † ‡

A population of dust-enshrouded objects orbiting the Galactic black hole

Weighing the Darkness: Astrometric Mass Measurement of Hidden Stellar Companions Using Gaia

Contact Info

Product

Resources

About

Individual Dynamical Masses of Ultracool Dwarfs* ^† ^‡

Individual Dynamical Masses of Ultracool Dwarfs* ^† ^‡