3D Selection of 167 Substellar Companions to Nearby Stars

Abstract

We analyze 5108 AFGKM stars with at least five high-precision radial velocity points, as well as Gaia and Hipparcos astrometric data, utilizing a novel pipeline developed in previous work. We find 914 radial velocity signals with periods longer than 1000 days. Around these signals, 167 cold giants and 68 other types of companions are identified, through combined analyses of radial velocity, astrometry, and imaging data. Without correcting for detection bias, we estimate the minimum occurrence rate of the wide-orbit brown dwarfs to be 1.3%, and find a significant brown-dwarf valley around 40 M Jup. We also find a power-law distribution in the host binary fraction beyond 3 au, similar to that found for single stars, indicating no preference of multiplicity for brown dwarfs. Our work also reveals nine substellar systems (GJ 234 B, GJ 494 B, HD 13724 b, HD 182488 b, HD 39060 b and c, HD 4113 C, HD 42581 d, HD 7449 B, and HD 984 b) that have previously been directly imaged, and many others that are observable at existing facilities. Depending on their ages, we estimate that an additional 10–57 substellar objects within our sample can be detected with current imaging facilities, extending the imaged cold (or old) giants by an order of magnitude.

Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin–Orbit Misalignments Are Common

“…Gl 229: This nearby (5.7614 ± 0.0006 pc; Gaia Collaboration et al 2022) M1 star hosts the first T dwarf companion to have been directly imaged (Nakajima et al 1994;Oppenheimer et al 1995;Oppenheimer 2014). With over 25 years of relative and absolute astrometry, the orbit and dynamical mass of Gl 229 B have now been exquisitely measured (Brandt et al 2020(Brandt et al , 2021bFeng et al 2022).…”

A dynamical mass for GJ 463 b: A massive super-Jupiter companion beyond the snow line of a nearby M dwarf

“…In this respect, GJ 463 b significantly adds to the small lot of objects (highlighted in Fig. 4) with joint constraints on their true masses from RVs and astrometry, that is GJ 676 A b,c (Sahlmann et al 2016;Feng et al 2022), andBD-17 0063 (Gaia Collaboration et al 2022a;Winn 2022). In this sample, GJ 463 b orbits the lowest-mass primary.…”

Orbital Migration of Protoplanets in a Marginally Gravitationally Unstable Disk. II. Migration, Merging, and Ejection

“…Their Figure 3 also shows orbital eccentricities varying from 0 to 0.75, again in basic agreement with the range evident in the present models in Figure 9. These Enzo models suggest a unified formation mechanism of the 167 substellar companions studied by Feng et al (2022): fragmentation of MGU disks. Galvagni et al (2012) used a smoothed particle hydrodynamics (SPH) code to study clumps formed at ∼100 au in an MGU disk, finding that the clumps could contract and heat up enough to begin molecular hydrogen dissociation, resulting in a dynamical collapse phase that can ensure their survival to tidal forces.…”

“…The large number of attempted ejections in the Enzo models that are listed in Table 2 fully support this hypothesis. Feng et al (2022) combined high-precision Doppler velocity data with Gaia and Hipparcos astrometry to constrain the masses and orbital parameters of 167 substellar companions to nearby stars. Their Figure 3 shows that these 167 companions fully populate a parameter space ranging from semimajor axes of ∼2 to ∼40 au, with masses from ∼4M Jup to ∼100M Jup , much like the upper right quadrant of Figure 7.…”