Exploring the circumstellar environment of the young eruptive star V2492 Cygni

Kóspál, Á.; Ábrahám, P.; Acosta–Pulido, J. A.; Morales, Maria; Balog, Z.; Carnerero, M. I.; Szegedi-Elek, E.; Farkas, A.; Henning, Th.; Kelemen, J.; Kun, M.; Márton, G.; Mészáros, Szabolcs; Moór, A.; Pál, András; Sárneczky, K.; Szakáts, R.; Szalai, N.; Szing, A.; Tóth, I.; Turner, Neal J.; Vida, K.

doi:10.1051/0004-6361/201220553

Cited by 28 publications

(30 citation statements)

References 32 publications

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“…Both the continuum-based mass calculation and line-based mass and column density calculation depend strongly on the used envelope temperatures. For most of our target regions the excitation temperatures derived from the optically thick 13 CO emission are consistent with the 20−50 K temperatures used by studies of YSO envelopes (Andre & Montmerle 1994;Hogerheijde et al 1999;Sandell & Weintraub 2001;Lommen et al 2008;Dunham et al 2012;Green et al 2013;Kóspál et al 2013). The APEX study by Kóspál et al (2017) derived lower temperatures (5−7 K) for lower mass envelopes and higher temperatures (> 50 K) for high-mass envelopes.…”

Section: Discussionsupporting

confidence: 79%

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

Fehér

Kóspál

Ábrahám

et al. 2017

A&A

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Context. FU Orionis-type objects are pre-main sequence, 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 physical conditions inside 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. Aims. We characterize the morphology and the physical parameters of the circumstellar material around FU Orionis-type stars using the emission of millimeter wavelength molecular tracers. The high spatial resolution study gives insight into the evolutionary state of the objects, the distribution of parameters in the envelopes and the physical processes forming the environment of these stars. Methods. 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 determine the spatial and velocity structure of the circumstellar gas on the scale of a few thousands of AU. We derive temperatures and envelope masses and discuss the kinematics of the circumstellar material. Results. 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 ; 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 that can be interpreted as envelopes but there are many other clumps in their environments. Traces of outflow activity were observed towards V1735 Cyg, V733 Cep and V710 Cas. Conclusions. 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. We also find evidence of larger scale circumstellar material influencing the detected spectral features in the environment of our targets. These 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.

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Section: Discussionsupporting

confidence: 79%

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

Fehér

Kóspál

Ábrahám

et al. 2017

A&A

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“…Objects like this are Hα11, PV Cep, V1647 Ori, and V899 Mon (Kun et al 2011a,b;Mosoni et al 2013;Ninan et al 2015). V346 Nor also resembles the young eruptive star V2492 Cyg in several aspects: the pre-outburst position of V2492 Cyg in the near-IR color-color diagram is close to the point of the 2010 minimum of V346 Nor, it also underwent a large accretion change at the beginning of its outburst, and in the high state, the line-of-sight extinction varies continuously (Kóspál et al 2011(Kóspál et al , 2013Hillenbrand et al 2013). Therefore, the observed variability in both V346 Nor and V2492 Cyg is governed by a combination of changing accretion and extinction.…”

Section: Discussionmentioning

confidence: 99%

Brightness variations of the FUor-type eruptive star V346 Normae

Kóspál

Ábrahám

Westhues

et al. 2017

A&A

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Decades after the beginning of its FU Orionis-type outburst, V346 Nor unexpectedly underwent a fading event of ∆K = 4.6 mag around 2010. We obtained near-infrared observations and re-analyzed data from the VISTA/VVV survey to outline the brightness evolution. In our VLT/NaCO images, we discovered a halo of scattered light around V346 Nor with a size of about 0 . 04 (30 au). The VISTA data outlined a well-defined minimum in the light curve in late 2010/early 2011, and tentatively revealed a small-amplitude periodic modulation of 58 days. Our latest data points from 2016 demonstrate that the source is still brightening but has not yet reached the 2008 level. We used a simple accretion disk model with varying accretion rate and line-of-sight extinction to reproduce the observed near-infrared magnitudes and colors. We found that the flux changes of V346 Nor before 2008 were caused by a correlated change of extinction and accretion rate, while the minimum around 2010 was mostly due to decreasing accretion. The source reached a highest accretion rate of ≈10 −4 M yr −1 in 1992. A combination of accretion and extinction changes has been invoked in the literature to interpret the flux variations of certain embedded young eruptive stars.

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“…This component, as well as the many other detected variable signatures, may relate to shell phases and outbursts. These are also seen in both post-and pre-main-sequence objects (Crause et al 2003;Kóspál et al 2013;Ellerbroek et al 2014). Peculiar spectral profiles (He , Mg , Si ) indicate either infall or outflow, and are thus inconclusive regarding the evolutionary state.…”

Section: Evolutionary Statementioning

confidence: 99%

A resolved, au-scale gas disk around the B[e] star HD 50138

Ellerbroek

Benisty

Kraus

et al. 2014

A&A

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HD 50138 is a B[e] star surrounded by a large amount of circumstellar gas and dust. Its spectrum shows characteristics which may indicate either a pre-or a post-main-sequence system. Mapping the kinematics of the gas in the inner few au of the system contributes to a better understanding of its physical nature. We present the first high spatial and spectral resolution interferometric observations of the Brγ line of HD 50138, obtained with VLTI/AMBER. The line emission originates in a region more compact (up to 3 au) than the continuum-emitting region. Blue-and red-shifted emission originates from the two different hemispheres of an elongated structure perpendicular to the polarization angle. The velocity of the emitting medium decreases radially. An overall offset along the NW direction between the line-and continuum-emitting regions is observed. We compare the data with a geometric model of a thin Keplerian disk and a spherical halo on top of a Gaussian continuum. Most of the data are well reproduced by this model, except for the variability, the global offset and the visibility at the systemic velocity. The evolutionary state of the system is discussed; most diagnostics are ambiguous and may point either to a post-main-sequence or a pre-main-sequence nature.

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Exploring the circumstellar environment of the young eruptive star V2492 Cygni

Cited by 28 publications

References 32 publications

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

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

Brightness variations of the FUor-type eruptive star V346 Normae

A resolved, au-scale gas disk around the B[e] star HD 50138

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