Constraining the properties of HD 206893 B

Grandjean, A.; Lagrange, A.-M.; Beust, H.; Rodet, L.; Milli, J.; Rubini, P.; Babusiaux, C.; Meunier, N.; Delorme, P.; Aigrain, S.; Zicher, N.; Bonnefoy, M.; Biller, Beth; Baudino, J. L.; Bonavita, M.; Boccaletti, A.; Cheetham, A.; Girard, J.; Hagelberg, J.; Janson, Markus; Lannier, J.; Lazzoni, C.; Ligi, R.; Maire, A. L.; Mesa, D.; Perrot, C.; Rouan, D.; Zurlo, A.

doi:10.1051/0004-6361/201935044

Cited by 42 publications

(80 citation statements)

References 19 publications

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“…We determine an eccentricity of e=0.25 +0.17 −0.14 with a 2σ credible interval of 0.0-0.44. Our constraints are narrower than the general unrestricted fit from Delorme et al and are similar to the recent results from Grandjean et al (2019), who also included relative astromety, RVs, and absolute astrometry of the host star from Hipparcos and Gaia in their orbit fit.…”

Section: Uniform Orbits With Literature Astrometrysupporting

confidence: 82%

“…When considering only orbits coplanar with the debris disk, this collapses to a range of about e=0.0-0.4. More recently, Grandjean et al (2019) combine relative astrometry, a radial acceleration, and astrometric acceleration measured between Hipparcos and Gaia to constrain the orbit and dynamical mass of HD 206893 B. They find a low eccentricity (e 0.4) and potential evidence of a second companion based on the larger-than-expected radial acceleration.…”

Section: Uniform Orbits With Literature Astrometrymentioning

confidence: 99%

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Population-level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels*

2020

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The orbital eccentricities of directly imaged exoplanets and brown dwarf companions provide clues about their formation and dynamical histories. We combine new high-contrast imaging observations of substellar companions obtained primarily with Keck/NIRC2 together with astrometry from the literature to test for differences in the population-level eccentricity distributions of 27 long-period giant planets and brown dwarf companions between 5-100 AU using hierarchical Bayesian modeling. Orbit fits are performed in a uniform manner for companions with short orbital arcs; this typically results in broad constraints for individual eccentricity distributions, but together as an ensemble these systems provide valuable insight into their collective underlying orbital patterns. The shape of the eccentricity distribution function for our full sample of substellar companions is approximately flat from e=0-1. When subdivided by companion mass and mass ratio, the underlying distributions for giant planets and brown dwarfs show significant differences. Low mass ratio companions preferentially have low eccentricities, similar to the orbital properties of warm Jupiters found with radial velocities and transits. We interpret this as evidence for in situ formation on largely undisturbed orbits within massive, extended disks. Brown dwarf companions exhibit a broad peak at e ≈ 0.6-0.9 with evidence for a dependence on orbital period. This closely resembles the orbital properties and period-eccentricity trends of wide (1-200 AU) stellar binaries, suggesting that brown dwarfs in this separation range predominantly form in a similar fashion. We also report evidence that the "eccentricity dichotomy" observed at small separations extends to planets on wide orbits: the mean eccentricity for the multiplanet system HR 8799 is lower than for systems with single planets. In the future, larger samples and continued astrometric orbit monitoring will help establish whether these eccentricity distributions correlate with other parameters such as stellar host mass, multiplicity, and age.

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Section: Uniform Orbits With Literature Astrometrysupporting

confidence: 82%

Section: Uniform Orbits With Literature Astrometrymentioning

confidence: 99%

Population-level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels*

2020

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“…HD206893 is a F5V star that hosts a directly imaged BD companion at a separation of 270 mas (Milli et al 2017;Delorme et al 2017). We recently reported in Grandjean et al (2019) a long-term trend in the star RV coupled with pulsations with periods slightly less than one day. We performed an MCMC on both the RV trend, imaging data, and HIPPARCOS-Gaia proper motion measurements to constrain the orbit and dynamical mass of the BD.…”

Section: Hd206893mentioning

confidence: 96%

A HARPS RV search for planets around young nearby stars

Grandjean

Lagrange

Keppler

et al. 2020

A&A

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Context. Young nearby stars are good candidates in the search for planets with both radial velocity (RV) and direct imaging techniques. This, in turn, allows for the computation of the giant planet occurrence rates at all separations. The RV search around young stars is a challenge as they are generally faster rotators than older stars of similar spectral types and they exhibit signatures of magnetic activity (spots) or pulsation in their RV time series. Specific analyses are necessary to characterize, and possibly correct for, this activity. Aims. Our aim is to search for planets around young nearby stars and to estimate the giant planet (GP) occurrence rates for periods up to 1000 days. Methods. We used the HARPS spectrograph on the 3.6 m telescope at La Silla Observatory to observe 89 A − M young (< 600 Myr) stars. We used our SAFIR (Spectroscopic data via Analysis of the Fourier Interspectrum Radial velocities ) software to compute the RV and other spectroscopic observables. Then, we computed the companion occurrence rates on this sample. Results. We confirm the binary nature of HD177171, HD181321 and HD186704. We report the detection of a close low mass stellar companion for HIP36985. No planetary companion was detected. We obtain upper limits on the GP (< 13 MJup) and BD (∈ [13; 80] MJup) occurrence rates based on 83 young stars for periods less than 1000 days, which are set, 2 +3 −2 % and 1 +3 −1 %.

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“…The orbital properties of HD206893B were revisited by Grandjean et al (2019), who performed a joint fit to radial velocity (RV) monitoring, Hipparcos and Gaia astrometry, and SPHERE and NaCo imaging to infer an orbital period for the companion of 21-33 yr. They derived its dynamical mass to be a potentially planetary mass of -+ M 10 4 5 Jup .…”

mentioning

confidence: 99%

“…They derived its dynamical mass to be a potentially planetary mass of -+ M 10 4 5 Jup . However, Grandjean et al (2019) noted that the fit appears dominated by the Hipparcos-Gaia proper-motion constraints, as the estimated mass from the joint fit is inconsistent at the 2σ level with the mass derived from the combination of only direct imaging astrometry and RV variation. The authors thus posit that the "B" companion cannot be responsible for the observed 1.6yr RV drift, and that this variation may correspond instead to an additional ∼15 M Jup interior companion with a short 1.6-4yr period.…”

mentioning

confidence: 99%

Gemini Planet Imager Spectroscopy of the Dusty Substellar Companion HD 206893 B

Ward-Duong

Patience

Follette

et al. 2020

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We present new near-infrared Gemini Planet Imager (GPI) spectroscopy of HD206893B, a substellar companion orbiting within the debris disk of its F5V star. The J, H, K1, and K2 spectra from GPI demonstrate the extraordinarily red colors of the object, confirming it as the reddest substellar object observed to date. The significant flux increase throughout the infrared presents a challenging atmosphere to model with existing grids. Best-fit values vary from 1200 to 1800 K for effective temperature and from 3.0 to 5.0 for log(g), depending on which individual wavelength band is fit and which model suite is applied. The extreme redness of the companion can be partially reconciled by invoking a high-altitude layer of submicron dust particles, similar to dereddening approaches applied to the peculiar red field L dwarf population. However, reconciling the HD206893B spectra with even those of the reddest low-gravity L dwarf spectra still requires the contribution of additional atmospheric

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Constraining the properties of HD 206893 B

Cited by 42 publications

References 19 publications

Population-level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels*

Population-level Eccentricity Distributions of Imaged Exoplanets and Brown Dwarf Companions: Dynamical Evidence for Distinct Formation Channels*

A HARPS RV search for planets around young nearby stars

Gemini Planet Imager Spectroscopy of the Dusty Substellar Companion HD 206893 B

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