Dynamical Mass of the Young Substellar Companion HD 984 B

Franson, Kyle; Bowler, Brendan P.; Brandt, Timothy D.; Dupuy, Trent J.; Tran, Quang H.; Brandt, G. Mirek; Li, Yiting; Kraus, Adam L.

doi:10.3847/1538-3881/ac35e8

Cited by 29 publications

(33 citation statements)

References 132 publications

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“…For example, the models of Baraffe et al (2003) convert a luminosity of  » L L log( ) -4.9 to 8 ± 1 M Jup (26 ± 4 M Jup ) at an age of 50 ± 10 Myr (500 ± 100 Myr); meanwhile, the same luminosity corresponds to 8 ± 2 M Jup (26 -+ 7 6 M Jup ) at 50 ± 20 Myr (500 ± 200 Myr). The corresponding fractional uncertainties for all cases in the list of Franson et al (2022) are larger than 16%, except for the planets around β Pic, which are 13% just as for HIP 21152 B. Furthermore, the majority (11/18) of the companions have fractional uncertainties higher than ∼30%.…”

Section: Discussionmentioning

confidence: 88%

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Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS*

Kuzuhara

Currie

Takuya

et al. 2022

ApJL

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We present the direct-imaging discovery of a substellar companion in orbit around a Sun-like star member of the Hyades open cluster. So far, no other substellar companions have been unambiguously confirmed via direct imaging around main-sequence stars in Hyades. The star HIP 21152 is an accelerating star as identified by the astrometry from the Gaia and Hipparcos satellites. We detected the companion, HIP 21152 B, in multiple epochs using the high-contrast imaging from SCExAO/CHARIS and Keck/NIRC2. We also obtained the stellar radial-velocity data from the Okayama 188 cm telescope. The CHARIS spectroscopy reveals that HIP 21152 B’s spectrum is consistent with the L/T transition, best fit by an early T dwarf. Our orbit modeling determines the semimajor axis and the dynamical mass of HIP 21152 B to be 17.5 − 3.8 + 7.2 au and 27.8 − 5.4 + 8.4 M Jup, respectively. The mass ratio of HIP 21152 B relative to its host is ≈2%, near the planet/brown dwarf boundary suggested by recent surveys. Mass estimates inferred from luminosity-evolution models are slightly higher (33–42 M Jup). With a dynamical mass and a well-constrained age due to the system’s Hyades membership, HIP 21152 B will become a critical benchmark in understanding the formation, evolution, and atmosphere of a substellar object as a function of mass and age. Our discovery is yet another key proof of concept for using precision astrometry to select direct-imaging targets.

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Section: Discussionmentioning

confidence: 88%

“…. Table1inFranson et al (2022) lists all the ages and dynamical masses of directly imaged substellar companions. We can compare those companions with HIP 21152 B, which has a fractional age uncertainty of 13% (100 Myr/750 Myr).…”

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confidence: 99%

Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS*

Kuzuhara

Currie

Takuya

et al. 2022

ApJL

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“…• HD 984 (or HIP 1134) is an F star hosting a brown dwarf with a mass of 61.0 ± 4.0 M Jup (Johnson-Groh et al 2017b;Franson et al 2022). Through combined analyses of the RV, Gaia-Hipparcos, and the imaging data collected by Franson et al (2022) and is labeled "KF22", we find a dynamical mass of 40.37 +24.33 −18.27 M Jup .…”

Section: Companionmentioning

confidence: 90%

3D Selection of 167 Substellar Companions to Nearby Stars

Feng

Butler

Vogt

et al. 2022

ApJS

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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.

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“…A significant challenge is the uncertain system age, which affects mass estimates of 51 Eri b based on substellar cooling models (e.g., Rajan et al 2017). As dynamical mass measurements of imaged substellar companions increase thanks to Gaia astrometry (e.g., Brandt et al 2021;Dupuy et al 2022;Franson et al 2022), precise ages are then needed to compare these dynamical masses to masses predicted from different cooling models and thereby test hot/warm/cold-start formation scenarios (e.g., Marley et al 2007;Spiegel & Burrows 2012;Mordasini 2013). Age estimates of the βPMG range from ∼8-40 Myr (e.g., Mamajek & Bell 2014, their Table 1).…”

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confidence: 99%

The Directly-Imaged Exoplanet Host Star 51 Eridani is a Gamma Doradus Pulsator

Sepulveda,

Huber,

Zhang

et al. 2022

Preprint

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51 Eri is well known for hosting a directly-imaged giant planet and for its membership to the β Pictoris moving group. Using two-minute cadence photometry from the Transiting Exoplanet Survey Satellite (TESS ), we detect multi-periodic variability in 51 Eri that is consistent with pulsations of Gamma Doradus (γ Dor) stars. We identify the most significant pulsation modes (with frequencies between ∼0.5-3.9 cycles/day and amplitudes ranging between ∼1-2 mmag) as dipole and quadrupole gravity-modes, as well as Rossby modes, as previously observed in Kepler γ Dor stars. Our results demonstrate that previously reported variability attributed to stellar rotation is instead likely due to γ Dor pulsations. Using the mean frequency of the l = 1 gravity-modes, together with empirical trends of the Kepler γ Dor population, we estimate a plausible stellar core rotation period of 0.9 +0.3 −0.1 days for 51 Eri. We find no significant evidence for transiting companions around 51 Eri in the residual light curve. The detection of γ Dor pulsations presented here, together with follow-up observations and modeling, may enable the determination of an asteroseismic age for this benchmark system. Future TESS observations would allow a constraint on the stellar core rotation rate, which in turn traces the surface rotation rate, and thus would help clarify whether or not the stellar equatorial plane and orbit of 51 Eri b are coplanar.

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Dynamical Mass of the Young Substellar Companion HD 984 B

Cited by 29 publications

References 132 publications

Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS*

Direct-imaging Discovery and Dynamical Mass of a Substellar Companion Orbiting an Accelerating Hyades Sun-like Star with SCExAO/CHARIS*

3D Selection of 167 Substellar Companions to Nearby Stars

The Directly-Imaged Exoplanet Host Star 51 Eridani is a Gamma Doradus Pulsator

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