Interferometric view of the circumstellar envelopes of northern FU Orionis-type stars

Abstract

FU Orionis-type objects are young, low-mass stars with large outbursts in visible light that last for several years or decades. They are thought to represent an evolutionary phase during the life of every young star when accretion from the circumstellar disk is enhanced during recurring time periods. These outbursts are able to rapidly build up the star while affecting the circumstellar disk and thus the ongoing or future planet formation. In many models infall from a circumstellar envelope seems to be necessary to trigger the outbursts. We observed the J=1$-$0 rotational transition of ${}^{13}$CO and C${}^{18}$O towards eight northern FU Orionis-type stars (V1057 Cyg, V1515 Cyg, V2492 Cyg, V2493 Cyg, V1735 Cyg, V733 Cep, RNO 1B and RNO 1C) and derive temperatures and envelope masses and discuss the morphology and kinematics of the circumstellar material. We detected extended CO emission associated with all our targets. Smaller scale CO clumps were found to be associated with five objects with radii of 2000$-$5000 AU and masses of 0.02$-$0.5 $M_{\odot }$; these are clearly heated by the central stars. Three of these envelopes are also strongly detected in the 2.7 mm continuum. No central CO clumps were detected around V733 Cep and V710 Cas but there are many other clumps in their environments. Traces of outflow activity were observed towards V1735 Cyg, V733 Cep and V710 Cas. The diversity of the observed envelopes enables us to set up an evolutionary sequence between the objects. We find their evolutionary state to range from early, embedded Class I stage to late, Class II-type objects with very low-mass circumstellar material. The results reinforce the idea of FU Orionis-type stars as representatives of a transitory stage between embedded Class I young stellar objects and classical T-Tauri stars.

17 pages, 11 figures; accepted for publication in A&A

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Cited by in corpus (13)

• Determining the recurrence timescale of long-lasting YSO outbursts
• Analysis of physical processes in eruptive YSOs with near infrared spectra and multi-wavelength light curves
• A multi-epoch, multi-wavelength study of the classical FUor V1515 Cyg approaching quiescence
• The most variable VVV sources: eruptive protostars, dipping giants in the Nuclear Disc and others
• Principal component analysis for estimating parameters of the L1287 dense core by fitting model spectral maps into observed ones
• VLA ammonia observations of L1287: analysis of the "Guitar" core and two filaments
• Grain growth in newly discovered young eruptive stars
• A Study of Millimeter Variability in FUor Objects
• Protostellar Outflows: a window to the past
• The Effelsberg survey of FU Orionis and EX Lupi objects I. -- Host environments of FUors/EXors traced by NH${}_3$
• Molecular inventory of a young eruptive star's environment -- Case study of the classical FU Orionis star V1057 Cyg
• The Effelsberg survey of FU~Orionis and EX~Lupi objects II. -- H${}_2$O maser observations
• A study of the photometric and spectroscopic variations of the prototypical FU Orionis-type star V1057 Cyg