| Name: Manoj Puravankara |
| Affiliation: Tata Institute of Fundamental Research, Mumbai |
| Conference ID: ASI2026_768 |
| Title: Warm molecular hydrogen in star forming clouds: New insights from the JWST |
| Abstract Type: Poster |
| Abstract Category: Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Author(s) and Co-Author(s) with Affiliation: Manoj Puravankara(TIFR, Mumbai - 400005, India), Himanshu Tyagi(TIFR, Mumbai - 400005, India), Vinod Pathak and IPA and HEFE Teams(TIFR, Mumabi - 400005, India) |
| Abstract: Recent JWST observations of young stellar objects have revealed the presence of warm and hot (500–3000 K) molecular hydrogen (H₂) winds, moving at velocities of 20–40 km/s. In addition to the pure rotational transitions of H₂ in the ground vibrational state and v = 1 level, JWST detects a rich set of high-lying ro-vibrational transitions (v = 1–0, 2–1 O(J)) from protostellar outflows. Excitation analyses indicate that this H₂ is predominantly shock-heated and collisionally excited.
Remarkably, the unprecedented sensitivity of JWST has enabled detection of high-excitation H₂ emission even in the ambient cloud material far from the protostar. We detect pure rotational transitions up to v = 0–0 S(18) (E_up = 27,643 K) and ro-vibrational lines such as v = 1–0 O(4), posing a significant question regarding the heating and excitation of this diffuse molecular gas. While irradiation by the interstellar UV field is a possible source, we detect similarly high-excitation H₂ emission even towards relatively isolated molecular environments, with low levels of UV irradiation.
In this contribution, we will present these surprising JWST results and discuss plausible excitation mechanisms, including shock dissipation, turbulent heating, cosmic-ray and particle excitation, and low-level UV pumping, that may contribute to producing warm molecular hydrogen emission in the ambient cloud. |
