EXors and the stellar birthline

Moody, Mackenzie; Stahler, Steven W.

doi:10.1051/0004-6361/201630196

Cited by 5 publications

(3 citation statements)

References 58 publications

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“…where M * and R * are the stellar mass and radius and R in is the inner truncation radius of the disk. We consider R * = 2 R ⊙ and M * = 0.7 M ⊙ , as evaluated from the EXor HR diagram recently published by Moody & Stahler (2017), while for the factor 1 − R * /R in we assumed a value of 0.8, which implies a typical inner disk radius R in = 5R * . The derived Ṁacc are reported in the final column of Table 5.…”

Section: Mass Accretion Rate Determinationmentioning

confidence: 99%

The 2016–2017 peak luminosity of the pre-main sequence variable V2492 Cygni

Giannini

Munari

Antoniucci

et al. 2018

A&A

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Context. V2492 Cyg is a young pre-main sequence star presenting repetitive brightness variations of significant amplitude (∆R ≥ 5 mag) whose physical origin has been ascribed to both extinction (UXor-type) and accretion (EXor-type) variability, although their mutual proportion has not been clarified yet. Recently, V2492 Cyg has reached a level of brightness ever registered in the period of its documented activity. Aims. We aim to derive the variation of the mass accretion rate between low-and high-state and to get new insights on the origin of the variability of V2492 Cyg. Methods. Optical and near-infrared photometry and spectroscopy have been obtained in October 2016 and between March and July 2017. The source has remained bright until the end of May 2017, then it started to rapidly fade since the beginning of June at a rate of ∼ 0.08 mag/day. On mid-July 2017 the source has reached the same low-brightness level as two years before. Extinction and mass accretion rate were derived by means of the luminosity of the brightest lines, in particular Hα and Hβ. A couple of optical high-resolution spectra are also presented to derive information on the gas kinematics. Results. Visual extinction variations do not exceed a few magnitudes, while the mass accretion rate is estimated to vary from less than 10 −8 up to a few 10 −7 M ⊙ yr −1 . This latter is comparable to that estimated on the previous high-state in 2010, likely occurred under more severe extinction conditions. Conclusions. The combined analysis of the optical and near-infrared (NIR) observations extends to the present event the original suggestion that the V2492 Cyg variability is a combination of changing extinction and accretion.

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Section: Mass Accretion Rate Determinationmentioning

confidence: 99%

The 2016–2017 peak luminosity of the pre-main sequence variable V2492 Cygni

Giannini

Munari

Antoniucci

et al. 2018

A&A

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“…This object could be periodic and the Lomb-Scargle analysis calculates a period of ∼ 970 days. In the third panel the object shows a single-epoch significant outburst (∆K s ≈ 1.5 mag), typical of EX Lupi (EXor)-type sources (Herbig 2007;Moody & Stahler 2017). This light curve is unique in our sample.…”

Section: Eruptivementioning

confidence: 80%

The VMC survey – XXXVI. Young stellar variability in the Large Magellanic Cloud

Zivkov

Oliveira

Petr-Gotzens

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Studies of young stellar objects (YSOs) in the Galaxy have found that a significant fraction exhibit photometric variability. However, no systematic investigation has been conducted on the variability of extragalactic YSOs. Here we present the first variability study of massive YSOs in a ∼ 1.5 deg 2 region of the Large Magellanic Cloud (LMC). The aim is to investigate whether the different environmental conditions in the metal-poor LMC (∼ 0.4 − 0.5 Z ) have an impact on the variability characteristics. Multi-epoch near-infrared (NIR) photometry was obtained from the VISTA Survey of the Magellanic Clouds (VMC) and our own monitoring campaign using the VISTA telescope. By applying a reduced χ 2 -analysis, stellar variability was identified. We found 3062 candidate variable stars from a population of 362 425 stars detected. Based on several Spitzer studies, we compiled a sample of high-reliability massive YSOs: a total of 173 massive YSOs have NIR counterparts (down to K s ∼ 18.5 mag) in the VMC catalogue, of which 39 display significant (> 3σ ) variability. They have been classified as eruptive, fader, dipper, short-term variable and long-period variable YSOs based mostly on the appearance of their K s band light curves. The majority of YSOs are aperiodic, only five YSOs exhibit periodic lightcurves. The observed amplitudes are comparable or smaller than those for Galactic YSOs (only two Magellanic YSOs exhibit ∆K s > 1 mag), not what would have been expected from the typically larger mass accretion rates observed in the Magellanic Clouds.

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“…GM Cha (ISO-Cha I 192) is a Class I/II source located in the Chameleon I dark cloud (Moody, & Stahler 2017;Mottram et al 2017). The source has no optical counterpart, is located in a region of high extinction (Jones et al 1985), and is associated with a 12 CO outflow (Mattila et al 1989;Mottram et al 2017).…”

Section: Sample Selection and Alma Observations 21 Target Samplementioning

confidence: 99%

ALMA Observations of Young Eruptive Stars: continuum disk sizes and molecular outflows

Hales,

Pérez,

Gonzalez-Ruilova

et al. 2020

Preprint

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We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm observations of four young, eruptive star-disk systems at 0. 4 resolution: two FUors (V582 Aur and V900 Mon), one EXor (UZ Tau E) and one source with an ambiguous FU/EXor classification (GM Cha). The disks around GM Cha, V900 Mon and UZ Tau E are resolved. These observations increase the sample of FU/EXors observed at sub-arcsecond resolution by 15%. The disk sizes and masses of FU/EXors objects observed by ALMA so far suggest that FUor disks are more massive than Class 0/I disks in Orion and Class II disks in Lupus of similar size. EXor disks in contrast do not seem to be distinguishable from these two populations. We reach similar conclusions when comparing the FU/EXor sample to the Class I and Class II disks in Ophiuchus. FUor disks around binaries are host to more compact disks than those in single-star systems, similar to non-eruptive young disks. We detect a wide-angle outflow around GM Cha in 12 CO emission, wider than typical Class I objects and more similar to those found around some FUor objects. We use radiative transfer models to fit the continuum and line data of the well-studied disk around UZ Tau E. The line data is well described by a keplerian disk, with no evidence of outflow activity (similar to other EXors). The detection of wide-angle outflows in FUors and not in EXors support to the current picture in which FUors are more likely to represent an accretion burst in the protostellar phase (Class I), while EXors are smaller accretion events in the protoplanetary (Class II) phase.

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EXors and the stellar birthline

Cited by 5 publications

References 58 publications

The 2016–2017 peak luminosity of the pre-main sequence variable V2492 Cygni

The 2016–2017 peak luminosity of the pre-main sequence variable V2492 Cygni

The VMC survey – XXXVI. Young stellar variability in the Large Magellanic Cloud

ALMA Observations of Young Eruptive Stars: continuum disk sizes and molecular outflows

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