Simultaneous X-ray, radio, near-infrared, and optical monitoring of young stellar objects in the Coronet cluster
- Autor(en)
- J. Forbrich, Th. Preibisch, K. M. Menten, Ralph Neuhäuser, F. M. Walter, M. Tamura, N. Matsunaga, N. Kusakabe, Y. Nakajima, A. Brandeker, S. Fornasier, B. Posselt, K. Tachihara, Christopher Broeg
- Abstrakt
Context: Multi-wavelength (X-ray to radio) monitoring of Young Stellar Objects (YSOs) can provide important information about physical processes at the stellar surface, in the stellar corona, and/or in the inner circumstellar disk regions. While coronal processes should mainly cause variations in the X-ray and radio bands, accretion processes may be traced by time-correlated variability in the X-ray and optical/infrared bands. Several multi-wavelength studies have been successfully performed for field stars and ~1-10 Myr old T Tauri stars, but so far no such study succeeded in detecting simultaneous X-ray to radio variability in extremely young objects like class I and class 0 protostars.
Aims: Here we present the first simultaneous X-ray, radio, near-infrared, and optical monitoring of YSOs, targeting the Coronet cluster in the Corona Australis star-forming region, which harbors at least one class 0 protostar, several class I objects, numerous T Tauri stars, and a few Herbig AeBe stars.
Methods: In August 2005, we obtained five epochs of Chandra X-ray observations on nearly successive days accompanied by simultaneous radio observations at the NRAO Very Large Array during four epochs, as well as by simultaneous optical and near-infrared observations from ground-based telescopes in Chile and South Africa.
Results: Seven objects are detected simultaneously in the X-ray, radio, and optical/infrared bands; they constitute our core sample. While most of these sources exhibit clear variability in the X-ray regime and several also display optical/infrared variability, none of them shows significant radio variability on the timescales probed. We also do not find any case of clearly time-correlated optical/infrared and X-ray variability. Remarkable intra-band variability is found for the class I protostar IRS 5 which shows much lower radio fluxes than in previous observations, and the Herbig Ae star R CrA, which displays enhanced X-ray emission during the last two epochs, but no time-correlated variations are seen for these objects in the other bands. The two components of S CrA vary nearly synchronously in the I band.
Conclusions: .The absence of time-correlated multi-wavelength variability suggests that there is no direct link between the X-ray and optical/infrared emission and supports the notion that accretion is not an important source for the X-ray emission of these YSOs. No significant radio variability was found on timescales of days.- Organisation(en)
- Institut für Astrophysik
- Externe Organisation(en)
- Friedrich-Schiller-Universität Jena, Max-Planck-Institut für extraterrestrische Physik, Max-Planck-Institut für Radioastronomie, National Astronomical Observatory of Japan, State University of New York, Stony Brook, University of Tokyo, Graduate University for Advanced Studies , University of Toronto, Université Paris VII - Paris-Diderot, Kobe University
- Journal
- Astronomy & Astrophysics
- Band
- 464
- Seiten
- 1003-1013
- ISSN
- 0004-6361
- DOI
- https://doi.org/10.1051/0004-6361:20066158
- Publikationsdatum
- 03-2007
- Peer-reviewed
- Ja
- ÖFOS 2012
- 103004 Astrophysik
- Schlagwörter
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/43c21888-7647-4b21-9128-d5e5675d46ee