DE0823−49 is a juvenile binary brown dwarf at 20.7 pc

Burgasser, Adam J.; Martín, E. L.; Lazorenko, P. F.; Gagliuffi, Daniella Bardalez; Mayor, M.; Ségransan, D.; Queloz, D.; Udry, S.

doi:10.1051/0004-6361/201425536

Cited by 12 publications

(12 citation statements)

References 42 publications

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“…The detection techniques each have their specificities regarding the accessible planet observables. Among them, astrometry is still in its infancy since, as of January 2016, only a handful of astrometric detections of exoplanet candidates have been announced, namely DE0823-49 b (Sahlmann et al 2015) and HD 176051 b (Muterspaugh et al 2010). Another candidate, VB 10 b, claimed to be detected by astrometry (Pravdo & Shaklan 2009), has been challenged by Bean et al (2010) and by Anglada-Escudé et al (2010).…”

Section: Introductionmentioning

confidence: 99%

Effects of disc asymmetries on astrometric measurements

Kral

Kennedy

Souami

2016

A&A

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Astrometry covers a parameter space that cannot be reached by RV or transit methods to detect terrestrial planets on wide orbits. In addition, high accuracy astrometric measurements are necessary to measure the inclination of the planet's orbits. Here we investigate the principles of an artefact of the astrometric approach, namely the displacement of the photo-centre owing to inhomogeneities in a dust disc around the parent star. Indeed, theory and observations show that circumstellar discs can present strong asymmetries. We model the pseudo-astrometric signal caused by these inhomogeneities, asking whether a dust clump in a disc can mimic the astrometric signal of an Earth-like planet. We show that these inhomogeneities cannot be neglected when using astrometry to find terrestrial planets. We provide the parameter space for which these inhomogeneities can affect the astrometric signals but still not be detected by mid-IR observations. We find that a small cross section of dust corresponding to a cometary mass object is enough to mimic the astrometric signal of an Earth-like planet. Astrometric observations of protoplanetary discs to search for planets can also be affected by the presence of inhomogeneities. Some further tests are given to confirm whether an observation is a real astrometric signal from a planet or an impostor. Eventually, we also study the case where the cross-section of dust is high enough to provide a detectable IR-excess and to have a measurable photometric displacement by actual instruments such as Gaia, IRAC, or GRAVITY. We suggest a new method, which consists of using astrometry to quantify asymmetries (clumpiness) in inner debris discs that cannot be otherwise resolved.

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Section: Introductionmentioning

confidence: 99%

Effects of disc asymmetries on astrometric measurements

Kral

Kennedy

Souami

2016

A&A

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“…The five available radial velocity measurements of the primary (Table 4) were modelled in a standard way. As discussed in Sahlmann et al (2015b) we do not expect significant offsets between the UVES and NIRSPEC instruments and can therefore model those data jointly. Since the radial velocity variation of the primary is fully characterised by the orbital parameters above, the inclusion of radial velocities adds only the systemic velocity γ as free parameter.…”

Section: Combined Astrometric Modelmentioning

confidence: 97%

“…Final fit parameters were determined from the mean and distribution of values in the final 800 steps, and a barycentric correction was applied to the inferred RV. We also re-evaluated the UVES data from Sahlmann et al (2015b) following similar methods, focusing on the 819 nm Na I doublet, which falls in a relatively high S/N = 34 region of the observed data. Table 4 summarizes the resulting atmospheric parameters and radial and rotational velocities determined by this analysis, while Figure 1 displays fits for one epoch each of the UVES and NIRSPEC data.…”

Section: Keck/nirc2 Lgs Aomentioning

confidence: 99%

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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“…In 2010 we started an astrometric planet search targeting 20 ultracool dwarfs and very low-mass stars (Sahlmann et al 2014(Sahlmann et al , 2015a. Observations were obtained with the FORS2/VLT camera (Appenzeller et al 1998), whose focal plane is composed of two CCD chips.…”

Section: Differential Ccd Data Sets Of Fors2 Field Starsmentioning

confidence: 99%

Gaiaand VLT astrometry of faint stars: Precision ofGaiaDR1 positions and updated VLT parallaxes of ultracool dwarfs

Lazorenko

2017

A&A

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Aims. We compared positions of the Gaia first data release (DR1) secondary data set at its faint limit with CCD positions of stars in 20 fields observed with the VLT/FORS2 camera. The FORS2 position uncertainties are smaller than one milli-arcsecond (mas) and allowed us to perform an independent verification of the DR1 astrometric precision. Methods. In the fields that we observed with FORS2, we projected the Gaia DR1 positions into the CCD plane, performed a polynomial fit between the two sets of matching stars, and carried out statistical analyses of the residuals in positions.Results. The residual RMS roughly matches the expectations given by the Gaia DR1 uncertainties, where we identified three regimes in terms of Gaia DR1 precision: for G ≃ 17 − 20 stars we found that the formal DR1 position uncertainties of stars with DR1 precisions in the range of 0.5-5 mas are underestimated by 63 ± 5%, whereas the DR1 uncertainties of stars in the range 7 − 10 mas are overestimated by a factor of two. For the best-measured and generally brighter G ≃ 16 − 18 stars with DR1 positional uncertainties of < 0.5 mas, we detected 0.44 ± 0.13 mas excess noise in the residual RMS, whose origin can be in both FORS2 and Gaia DR1. By adopting Gaia DR1 as the absolute reference frame we refined the pixel scale determination of FORS2, leading to minor updates to the parallaxes of 20 ultracool dwarfs that we published previously. We also updated the FORS2 absolute parallax of the Luhman 16 binary brown dwarf system to 501.42 ± 0.11 mas.

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DE0823−49 is a juvenile binary brown dwarf at 20.7 pc

Cited by 12 publications

References 42 publications

Effects of disc asymmetries on astrometric measurements

Effects of disc asymmetries on astrometric measurements

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

Gaiaand VLT astrometry of faint stars: Precision ofGaiaDR1 positions and updated VLT parallaxes of ultracool dwarfs

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