An Explanation of the Very Low Radio Flux of Young Planet-mass Companions

Wu, Ya-Lin; Close, Laird M.; Eisner, J. A.; Sheehan, Patrick

doi:10.3847/1538-3881/aa93db

Cited by 26 publications

(59 citation statements)

References 46 publications

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“…Nevertheless, we can still put constraints on the dust grain sizes and the disk's inclination and position angle, and through that constrain the rotational periods and formation mechanisms of the companions. Whereas we most likely detect polarization from the disks of DH Tau B and GSC 6214 B, no emission has been detected from these companions at mm-wavelengths (Bowler et al 2015;Wu et al 2017aWu et al , 2020Wolff et al 2017). It is therefore possible that these disks contain mostly micrometer-sized dust grains and only little mm-sized grains, or, as suggested by Wu et al (2017a), that the disks are compact and optically thick at mmwavelengths.…”

Section: Discussionmentioning

confidence: 60%

“…Indeed, a handful of substellar companions show evidence for the presence of an accretion disk through hydrogen emission lines, red near-infrared colors, and excess emission at mid-infrared A&A 647, A21 (2021) wavelengths (e.g., Seifahrt et al 2007;Bowler et al 2011;Bailey et al 2013;Kraus et al 2014;Zhou et al 2014;Haffert et al 2019). Interestingly, whereas ALMA and other radio interferometers have been successful at detecting the dust and gas of disks around isolated substellar objects (e.g., Ricci et al 2014;van der Plas et al 2016;Bayo et al 2017), attempts to detect such disks around substellar companions have almost exclusively yielded non-detections (Bowler et al 2015;MacGregor et al 2017;Wu et al 2017aWu et al ,b, 2020Wolff et al 2017;Ricci et al 2017;Pérez et al 2019). The only detection of a disk around a substellar companion at mm-wavelengths is that of PDS 70 c with ALMA by Isella et al (2019).…”

Section: Introductionmentioning

confidence: 99%

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A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS

Holstein

Stolker

Jensen-Clem

et al. 2021

A&A

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Context. Young giant planets and brown dwarf companions emit near-infrared radiation that can be linearly polarized up to several percent. This polarization can reveal the presence of an (unresolved) circumsubstellar accretion disk, rotation-induced oblateness of the atmosphere, or an inhomogeneous distribution of atmospheric dust clouds. Aims. We aim to measure the near-infrared linear polarization of 20 known directly imaged exoplanets and brown dwarf companions. Methods. We observed the companions with the high-contrast imaging polarimeter SPHERE-IRDIS at the Very Large Telescope. We reduced the data using the IRDAP pipeline to correct for the instrumental polarization and crosstalk of the optical system with an absolute polarimetric accuracy <0.1% in the degree of polarization. We employed aperture photometry, angular differential imaging, and point-spread-function fitting to retrieve the polarization of the companions. Results. We report the first detection of polarization originating from substellar companions, with a polarization of several tenths of a percent for DH Tau B and GSC 6214-210 B in H-band. By comparing the measured polarization with that of nearby stars, we find that the polarization is unlikely to be caused by interstellar dust. Because the companions have previously measured hydrogen emission lines and red colors, the polarization most likely originates from circumsubstellar disks. Through radiative transfer modeling, we constrain the position angles of the disks and find that the disks must have high inclinations. For the 18 other companions, we do not detect significant polarization and place subpercent upper limits on their degree of polarization. We also present images of the circumstellar disks of DH Tau, GQ Lup, PDS 70, β Pic, and HD 106906. We detect a highly asymmetric disk around GQ Lup and find evidence for multiple scattering in the disk of PDS 70. Both disks show spiral-like features that are potentially induced by GQ Lup B and PDS 70 b, respectively. Conclusions. The presence of the disks around DH Tau B and GSC 6214-210 B as well as the misalignment of the disk of DH Tau B with the disk around its primary star suggest in situ formation of the companions. The non-detections of polarization for the other companions may indicate the absence of circumsubstellar disks, a slow rotation rate of young companions, the upper atmospheres containing primarily submicron-sized dust grains, and/or limited cloud inhomogeneity.

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Section: Discussionmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS

Holstein

Stolker

Jensen-Clem

et al. 2021

A&A

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“…These indirect indicators of active accretion and/or the presence of IR/optical continuum excess have motivated efforts to directly detect these disks using the Atacama Large Millimeter/submillimeter Array (ALMA). Of the six PMCs in our sample 10 Myr old, five have prior ALMA observations: ROXs 42B b (Wu et al 2020), ROXs 12 b (Wu et al 2020), DH Tau b (Wu et al 2017(Wu et al , 2020, GSC 6214-210 b Wu et al 2017), and 2M1207-3932 b (Ricci et al 2017). None of these observations detected disks around these objects.…”

Section: Presence Of Cpds?mentioning

confidence: 80%

As the Worlds Turn: Constraining Spin Evolution in the Planetary-mass Regime

Bryan

Ginzburg

Chiang

et al. 2020

ApJ

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To understand how planetary spin evolves and traces planet formation processes, we measure rotational line broadening in eight planetary-mass objects (PMOs) of various ages (1–800 Myr) using near-infrared high-resolution spectra from NIRSPEC/Keck. Combining these with published rotation rates, we compile 27 PMO spin velocities, 16 of which derive from our NIRSPEC/Keck program. Our data are consistent with spin velocities v scaling with planetary radius R as v ∝ 1/R. We conclude that spin angular momentum is conserved as objects cool and contract over the sampled age range. The PMOs in our sample spin at rates that are approximately an order of magnitude below their break-up values, consistent with the hypothesis that they were spun down by magnetized circum-PMO disks (CPDs) during the formation era at ages ≲a few Myr. There is a factor of 4–5 variation in spin velocity that has yet to be understood theoretically. It also remains to be seen whether spin evolves on timescales ≳1 Gyr for PMOs, as it does for stars and high-mass brown dwarfs emitting magnetized winds.

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“…The velocity resolution is 0.85 km s −1 for CO(3-2) and 0.32 km s −1 for CO(2-1). Details of the observations can be found in Wu et al (2017) and Wu et al (2020). After standard data reduction with CASA (McMullin et al 2007), we used pdspy (Sheehan et al 2019) to model the gas kinematics.…”

Section: Analysis and Resultsmentioning

confidence: 99%

Dynamical Masses of Young Stars Inferred from Two Transitions of CO with ALMA

Premnath

Bowler

et al. 2020

Res. Notes AAS

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Stellar masses are fundamental but often difficult to measure. Thanks to the Atacama Large Millimeter Array (ALMA) and Gaia, dynamical masses of pre-main sequence stars can be precisely measured using the Keplerian rotation of protoplanetary disks. We used ALMA CO(2-1) and CO(3-2) observations of CT Cha and DS Tau to determine their masses by modeling the geometry, kinematics, and physical properties of their disks with a Bayesian-based radiative transfer modeling code (pdspy). We found that the posterior distributions of the masses from the two transitions are inconsistent at the 2-4 σ level. These systematic errors may originate from assumptions in the disk model, or perhaps the modest spatial or spectral resolutions used in this study. Regardless, this indicates that dynamical mass measurements using disk kinematics should be treated with caution when using only a single transition line because of these systematic errors.

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An Explanation of the Very Low Radio Flux of Young Planet-mass Companions

Cited by 26 publications

References 46 publications

A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS

A survey of the linear polarization of directly imaged exoplanets and brown dwarf companions with SPHERE-IRDIS

As the Worlds Turn: Constraining Spin Evolution in the Planetary-mass Regime

Dynamical Masses of Young Stars Inferred from Two Transitions of CO with ALMA

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