An ALMA Study of the FU Ori─type Object V900 Mon: Implications for the Progenitor

Takami, Michihiro and Chen, Tsu-Sheng and Liu, Hauyu Baobab and Hirano, Naomi and Kóspál, Ágnes and Ábrahám, Péter and Fernando, Cruz-Saenz de Miera and Csengeri, Tímea and Chen, Lei (2019) An ALMA Study of the FU Ori─type Object V900 Mon: Implications for the Progenitor. ASTROPHYSICAL JOURNAL, 884. ISSN 1538-4357

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Abstract

We present ALMA observations of 12CO, 13CO, and C18O J = 2─1 lines and the 230 GHz continuum for the F Ori─type object (FUor) V900 Mon (d ∼ 1.5 kpc), for which the accretio burst was triggered between 1953 and 2009. We identified CO emissio associated with a molecular bipolar outflow extending up to a ∼104 au scale and a rotating molecular envelope extendin over >104 au. The interaction with the hot energetic FUo wind, which was observed using optical spectroscopy, appears limited t a region within ∼400 au of the star. The envelope mass and collimatio of the extended CO outflow suggest that the progenitor of this FUor is low-mass Class I young stellar object (YSO). These parameters for V90 Mon, another FUor, and a few FUor-like stars are consistent with th idea that FUor outbursts are associated with normal YSOs. The continuu emission is marginally resolved in our observations with a 0.″2 × 0.″1 (∼300 × 225 au) beam, and a Gaussian model provides a deconvolved FWH of ∼90 au. The emission is presumably associated with a dust circumstellar disk, plus a possible contribution from a wind or win cavity close to the star. The warm compact nature of the disk continuu emission could be explained with viscous heating of the disk, whil gravitational fragmentation in the outer disk and/or a combination o grain growth and their inward drift may also contribute to its compac nature.

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