H₂ flows in the Corona Australis cloud and their driving sources

M. S. N. Kumar, S. Sharma, C. J. Davis, J. Borissova, J. M. C. Grave

Abstract
Aims. To uncover the H₂ flows in the Corona Australis molecular cloud and in particular identify the flows from the Coronet cluster.
Methods. A deep, near-infrared H₂ v=1–0 S(1), 2.122µm line narrow band imaging survey of the R CrA cloud core was carried out. The nature of all candidate driving sources in the region was evaluated using data available from literature and also by fitting the spectral energy distributions (SED) of each source either with an extincted photosphere or YSO model. Archival Spitzer-IRAC and MIPS data was used to obtain photometry, which was combined with USNO, 2MASS catalogs and millimeter photometry from literature, to build the SEDs. We identify the best candidate driving source for each outflow by comparing the flow properties, available proper motions, and the known/estimated properties of the driving sources. We also adopted the thumbrule of outflow power being proportional to source luminosity and inversely proportional to the source age to reach a consensus.
Results. Continuum-subtracted narrow-band images reveal several new Molecular Hydrogen emission-line Objects (MHOs). Together with previously known MHOs and Herbig-Haro objects we catalogue at least 14 individual flow components of which 11 appear to be driven by the R CrA aggregate members. The flows originating from the Coronet cluster have lengths of ∼0.1-0.2 pc. Eight out of nine submillimeter cores mapped in the Coronet cluster region display embedded stars driving an outflow component. Roughly 80% of the youngest objects in the Coronet are associated with outflows. The MHO flows to the west of the Coronet display lobes moving to the west and vice-versa, resulting in non-detections of the counter-lobe in our deep-imaging. We speculate that these counter-flows may be experiencing a stunting effect in penetrating the dense central core.
Conclusions. Although this work has reduced the ambiguities for many flows in the Coronet region, one of the brightest H₂ feature (MHO2014) and a few fainter features in the region remain unassociated with a clear driving source. The flows from Coronet, therefore, continue to be interesting targets for future studies.

Keywords
stars: formation – ISM: jets and outflows – stars: variables: T Tauri, Herbig Ae/Be – Herbig-Haro objects

Notes
Figure 1 is available in electronic form at http://www.aanda.org

Astronomy and Astrophysics
Volume 533, Page A137_1
September 2011

>> ADS>> DOI