Molecules in the disk orbiting the twin young suns of V4046 Sgr

Abstract

We report the results of a mm-wave molecular line survey of the nearby (D ~ 70 pc), 12 Myr-old system V4046 Sgr -- a tight (9 R_sun separation), short-period (2.42 day) binary with nearly equal component masses of ~0.9 M_sun -- conducted with the 30 m telescope of the Institut de Radio Astronomie Millimetrique (IRAM). We detected rotational transitions of 12CO 13CO, HCN, CN, and HCO+. The double-peaked CO line profiles of V4046 Sgr are well fit by a model invoking a Keplerian disk with outer radius of ~250 AU that is viewed at an inclination i = 35 degrees. We infer minimum disk gas and dust masses of ~13 and ~20 Earth masses from the V4046 Sgr CO line and submm continuum fluxes, respectively. The actual disk gas mass could be much larger if the gas-phase CO is highly depleted and/or 13CO is very optically thick. The overall similarity of the circumbinary disk of V4046 Sgr to the disk orbiting the single, ~8 Myr-old star TW Hya -- a star/disk system often regarded as representative of the early solar nebula -- indicates that gas giant planets are likely commonplace among close binary star systems. Given the relatively advanced age and proximity of V4046 Sgr, these results provide strong motivation for future high-resolution imaging designed to ascertain whether a planetary system now orbits its twin suns.

5 pages, 3 figures; to appear in Astronomy & Astrophysics

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• Resolving the chemistry in the disk of TW Hydrae I. Deuterated species
• On the formation and migration of giant planets in circumbinary discs
• A Resolved Molecular Gas Disk around the Nearby A Star 49 Ceti
• X-ray accretion signatures in the close CTTS binary V4046 Sgr
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• Unbiased mm-wave Line Surveys of TW Hya and V4046 Sgr: The Enhanced C2H and CN Abundances of Evolved Protoplanetary Disks
• Molecules with ALMA at Planet-forming Scales (MAPS) XI: CN and HCN as Tracers of Photochemistry in Disks
• Scattered Light from Dust in the Cavity of the V4046 Sgr Transition Disk
• Spatially resolved HCN J=4--3 and CS J=7--6 emission from the disk around HD 142527
• New debris disks in nearby young moving groups
• Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk
• An Unbiased 1.3 mm Emission Line Survey of the Protoplanetary Disk Orbiting LkCa 15
• On The Unusual Variability of 2MASS J06195260-2903592: A Long-Lived Disk around a Young Ultracool Dwarf
• Nearby Young Stars and Young Moving Groups