Volume 551, March 2013
|Number of page(s)||12|
|Section||Interstellar and circumstellar matter|
|Published online||22 February 2013|
1 Research and Scientific Support Department, European Space Agency (ESA, ESTEC, SRE-SA), PO Box 299, 2200 AG, Noordwijk, The Netherlands
2 Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary
3 Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
4 Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
5 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
6 Department of Astronomy, Loránd Eötvös University, Pázmány P. st. 1/A, 1117 Budapest, Hungary
7 ELTE Gothard − Lendület Research Group, 9700 Szombathely, Hungary
8 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
Received: 13 October 2012
Accepted: 3 January 2013
Context. V2492 Cyg is a young eruptive star that went into outburst in 2010. The near-infrared color changes observed since the outburst peak suggest that the source belongs to a newly defined sub-class of young eruptive stars, where time-dependent accretion and variable line-of-sight extinction play a combined role in the flux changes.
Aims. In order to learn about the origin of the light variations and to explore the circumstellar and interstellar environment of V2492 Cyg, we monitored the source at ten different wavelengths, between 0.55 μm and 2.2 μm from the ground and between 3.6 μm and 160 μm from space.
Methods. We analyze the light curves and study the color−color diagrams via comparison with the standard reddening path. We examine the structure of the molecular cloud hosting V2492 Cyg by computing temperature and optical depth maps from the far-infrared data.
Results. We find that the shapes of the light curves at different wavelengths are strictly self-similar and that the observed variability is related to a single physical process, most likely variable extinction. We suggest that the central source is episodically occulted by a dense dust cloud in the inner disk and, based on the invariability of the far-infrared fluxes, we propose that it is a long-lived rather than a transient structure. In some respects, V2492 Cyg can be regarded as a young, embedded analog of UX Orionis-type stars.
Conclusions. The example of V2492 Cyg demonstrates that the light variations of young eruptive stars are not exclusively related to changing accretion. The variability provided information on an azimuthally asymmetric structural element in the inner disk. Such an asymmetric density distribution in the terrestrial zone may also have consequences for the initial conditions of planet formation.
Key words: stars: formation / circumstellar matter / infrared: stars / stars: individual: V2492 Cyg
This work is based on observations made with the Herschel Space Observatory and with the Spitzer Space Telescope. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. Spitzer is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.
Tables 1 and 2 are available in electronic form at http://www.aanda.org
© ESO, 2013
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