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Register a new userMultiple outflows from the luminous YSO IRAS 07422-2001
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Watson Varricatt P.
Publication date
2012
fields
Physics
and research's language is
English
Authors
Watson P. Varricatt
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The luminous Young Stellar Object (YSO) IRAS 07422-2001 is studied in the infrared. We discover star forming activity in embedded clusters located in a cloud detected at mid-IR wavelengths in emission. Multiple outflows are discovered from these clusters in the H_2 ro-vibrational line at 2.122 micron. We detect at least six outflows from the cluster associated with the IRAS source and another outflow from a source located in a cluster detected ~2.7 arcmin NE of the IRAS source. Additional star formation is taking place in two other cluster candidates within the cloud. Three of the YSOs in the cluster associated with the IRAS source are detected at 11.2 micron at an angular resolution of ~0.8 arcsec. We have a tentative detection of a circumstellar disk in this cluster, seen as an extinction lane in the J and H-band images. The spectral energy distributions (SEDs) of the dominant YSOs in the cluster associated with the IRAS source and in the NE cluster are studied using radiative transfer models and the properties of the YSOs are estimated. The YSO associated with the IRAS source is probably in a very early Class I stage of formation. The source identified as the dominant YSO in the NE cluster appears to be older than the dominant YSO in the cluster associated with the IRAS source, but its observed flux seems to be contaminated by extra emission, which suggests the presence of a young source contributing to the SED at far-IR wavelengths. The star formation observed in the field of IRAS 07422-2001 supports the idea of hierarchical formation of massive star clusters and the growth of massive young stellar objects near the centres of multiple sub-clusters in a star forming clump through competitive accretion.
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Aims: We aim to understand the star formation associated with the luminous young stellar object (YSO) IRAS 18345-0641 and to address the complications arising from unresolved multiplicity in interpreting the observations of massive star-forming regions. Methods: New infrared imaging data at sub-arcsec spatial resolution are obtained for IRAS 18345-0641. The new data are used along with mid- and far-IR imaging data, and CO (J=3-2) spectral line maps downloaded from archives to identify the YSO and study the properties of the outflow. Available radiative-transfer models are used to analyze the spectral energy distribution (SED) of the YSO. Results: Previous tentative detection of an outflow in the H_2 (1-0) S1 line (2.122 micron) is confirmed through new and deeper observations. The outflow appears to be associated with a YSO discovered at infrared wavelengths. At high angular resolution, we see that the YSO is probably a binary. The CO (3--2) lines also reveal a well defined outflow. Nevertheless, the direction of the outflow deduced from the H_2 image does not agree with that mapped in CO. In addition, the age of the YSO obtained from the SED analysis is far lower than the dynamical time of the outflow. We conclude that this is probably caused by the contributions from a companion. High-angular-resolution observations at mid-IR through mm wavelengths are required to properly understand the complex picture of the star formation happening in this system, and generally in massive star forming regions, which are located at large distances from us.
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