Extreme infrared variables from UKIDSS – I. A concentration in star-forming regions

Peña, C. Contreras; Lucas, P. W.; Froebrich, D.; Kumar, M. S. N.; Goldstein, Jonathan; Drew, J. E.; Adamson, A. J.; Davis, C. J.; Barentsen, Geert; Wright, N. J.

doi:10.1093/mnras/stu063

Cited by 31 publications

(37 citation statements)

References 115 publications

(183 reference statements)

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“…The distinction between the two classes lies in the magnitude of the outburst, the increase of accretion, the shape of the light curve, and the spectral features observed during outburst. The characteristics of individual objects do not always fully coincide with one of the classes (Herczeg et al 2016), and some authors have suggested that the two classes (or at least, a subset of them) are part of a continuous spectrum of outbursting stars (Contreras Peña et al 2014.…”

Section: Introductionmentioning

confidence: 99%

The 2014–2017 outburst of the young star ASASSN-13db

Sicilia‐Aguilar

Oprandi

Froebrich

et al. 2017

A&A

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Context. Accretion outbursts are key elements in star formation. ASASSN-13db is a M5-type star with a protoplanetary disk, the lowest-mass star known to experience accretion outbursts. Since its discovery in 2013, it has experienced two outbursts, the second of which started in November 2014 and lasted until February 2017. Aims. We explore the photometric and spectroscopic behavior of ASASSN-13db during the 2014-2017 outburst. Methods. We use high-and low-resolution spectroscopy and time-resolved photometry from the ASAS-SN survey, the LCOGT and the Beacon Observatory to study the lightcurve of ASASSN-13db and the dynamical and physical properties of the accretion flow. Results. The 2014-2017 outburst lasted for nearly 800 days. A 4.15d period in the light curve likely corresponds to rotational modulation of a star with hot spot(s). The spectra show multiple emission lines with variable inverse P-Cygni profiles and a highly variable blue-shifted absorption below the continuum. Line ratios from metallic emission lines (Fe I/Fe II, Ti I/Ti II) suggest temperatures of ∼5800-6000 K in the accretion flow. Conclusions. Photometrically and spectroscopically, the 2014-2017 event displays an intermediate behavior between EXors and FUors. The accretion rate (Ṁ=1-3×10−7 M /yr), about two orders of magnitude higher than the accretion rate in quiescence, is not significantly different from the accretion rate observed in 2013. The absorption features in the spectra suggest that the system is viewed at a high angle and drives a powerful, non-axisymmetric wind, maybe related to magnetic reconnection. The properties of ASASSN-13db suggest that temperatures lower than those for solar-type stars are needed for modeling accretion in very-low-mass systems. Finally, the rotational modulation during the outburst reveals that accretion-related structures settle after the beginning of the outburst and can be relatively stable and long-lived. Our work also demonstrates the power of time-resolved photometry and spectroscopy to explore the properties of variable and outbursting stars.

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Section: Introductionmentioning

confidence: 99%

The 2014–2017 outburst of the young star ASASSN-13db

Sicilia‐Aguilar

Oprandi

Froebrich

et al. 2017

A&A

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“…The longer exposure time for K s aims at increasing the likelihood of detecting young variables since several Galactic studies have shown that variability in this filter is common amongst young stars (e.g. Contreras Peña et al 2014;Lucas et al 2017). It also allows us to better probe high-extinction regions, where young stars are preferentially located.…”

Section: Complementary Datamentioning

confidence: 99%

“…Cody et al 2014) and high amplitude variability is more common (e.g. Contreras Peña et al 2014). These YSOs are also luminous enough to be reliably detected in the individual pawprints.…”

Section: Spitzer Source Selectionmentioning

confidence: 99%

“…Long variability timescales (weeks or longer) and large amplitudes of ∆K s > 1 mag dominate amongst stars in early evolutionary stages (e.g. Class I protostars; Contreras Peña et al 2014), likely as a result of unsteady mass accretion. More evolved PMS stars show on average smaller variability amplitudes (usually ∆K s < 0.5 mag) and shorter periods (P 15 d), caused by obscuring structures in the inner circumstellar disc (for Class II objects), or by photospheric phenomena like cool and/or hot spots (for Class III and Class II sources).…”

Section: Introductionmentioning

confidence: 99%

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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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“…Two epochs in the near-IR were obtained during the UKIDDS Galactic Plane Survey (the UGPS) (Contreras Peña et al 2014), but only finding an additional 4 examples arising from embedded sources.…”

Section: Accretion Events In Star Formationmentioning

confidence: 99%

Scientific Goals of the Kunlun Infrared Sky Survey (KISS)

Burton

Zheng²,

Mould

et al. 2016

Publ. Astron. Soc. Aust.

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The high Antarctic plateau provides exceptional conditions for conducting infrared observations of the cosmos on account of the cold, dry and stable atmosphere above the ice surface. This paper describes the scientific goals behind the first program to examine the time-varying universe in the infrared from Antarctica -the Kunlun Infrared Sky Survey (KISS). This will employ a small (50 cm aperture) telescope to monitor the southern skies in the 2.4µm K dark window from China's Kunlun station at Dome A, on the summit of the Antarctic plateau, through the uninterrupted 4-month period of winter darkness. An earlier paper discussed optimisation of the K dark filter for the best sensitivity (Li et al. 2016). This paper examines the scientific program for KISS. We calculate the sensitivity of the camera for the extrema of observing conditions that will be encountered. We present the parameters for sample surveys that could then be carried out for a range of cadences and sensitivities. We then discuss several science programs that could be conducted with these capabilities, involving star formation, brown dwarfs and hot Jupiters, exoplanets around M dwarfs, the terminal phases of stellar evolution, discovering fast transients as part of multi-wavelength campaigns, embedded supernova searches, reverberation mapping of active galactic nuclei, gamma ray bursts and the detection of the cosmic infrared background.

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Extreme infrared variables from UKIDSS – I. A concentration in star-forming regions

Cited by 31 publications

References 115 publications

The 2014–2017 outburst of the young star ASASSN-13db

The 2014–2017 outburst of the young star ASASSN-13db

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

Scientific Goals of the Kunlun Infrared Sky Survey (KISS)

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