ALMA Measurements of Circumstellar Material in the GQ Lup System
ALMA Measurements of Circumstellar Material in the GQ Lup System
Authors:
MacGregor et al
Abstract:
We present ALMA observations of the GQ Lup system, a young Sun-like star with
a substellar mass companion in a wide-separation orbit. These observations of
870 μm continuum and CO J=3-2 line emission with beam size ∼0.3″
(∼45 AU) resolve the disk of dust and gas surrounding the primary star, GQ
Lup A, and provide deep limits on any circumplanetary disk surrounding the
companion, GQ Lup b. The circumprimary dust disk is compact with a FWHM of
59±12 AU, while the gas has a larger extent with a characteristic radius of
46.5±1.8 AU. By forward-modeling the velocity field of the circumprimary
disk based on the CO emission, we constrain the mass of GQ Lup A to be M∗=(1.03±0.05)∗(d/156 pc) M⊙, where d is a known distance, and
determine that we view the disk at an inclination angle of
60.5∘±0.5∘ and a position angle of 346∘±1∘. The
3σ upper limit on the 870 μm flux density of any circumplanetary
disk associated with GQ Lup b of <0.15 mJy implies an upper limit on the dust
disk mass of <0.04 M⊕ for standard assumptions about optically thin
emission. We discuss proposed mechanisms for the formation of wide-separation
substellar companions given the non-detection of circumplanetary disks around
GQ Lup b and other similar systems.
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