| Name: | Himanshu Tyagi |
| Affiliation: | Tata Institute of Fundamental Research Mumbai |
| Conference ID : | ASI2022_257 |
| Title : | The origin of water emission in protostars: Breaking the shock degeneracy. |
| Authors : | Himanshu Tyagi, Mayank Narang, Manoj Puravankara |
| Abstract Type: | Poster |
| Abstract Category : | Stars, ISM and Galaxy |
| Abstract : | Water in molecular clouds can form very efficiently above temperatures ~400 K by neutral-neutral reactions. It becomes the dominant coolant at low temperatures and relatively high densities (>10^3 per cc). As radiative cooling is a crucial process in star formation, understanding the water line emission mechanism from the protostars is an essential step in completing the star formation puzzle. Strong water emission lines have been detected towards several protostars by Spitzer and Herschel space telescopes. Past studies investigating the origin of the high excitation mid-IR water lines in protostars have not conclusively identified the exact emission mechanism. While shocks as the origin of these lines are generally accepted, the exact mechanism that produces these shocks is still debated. Two shock mechanisms are proposed: (a) envelope -- disk accretion generating shocks at the disk’s surface, (b) shocks produced in outflows. The class 0 protostar IRAS 13036-7644 in the Chamaeleon II cloud is one such strong water emitter, where several strong water and OH lines have been detected in the Spitzer high-resolution spectrum. We carry out an excitation analysis of the water and CO emission lines in the Spitzer/IRS and Herschel/PACS spectra to break this degeneracy between water emission mechanisms. We will present our results for IRAS 13036-7644 and discuss the possible excitation mechanisms. |