Astron. Astrophys. 315, L181-L184 (1996)
Thermal H2O emission from the Herbig-Haro flow HH 54*
R. Liseau1,2, C. Ceccarelli3,2, B. Larsson1, B. Nisini2, G.J. White4, P. Ade4, C. Armand5, M. Burgdorf5, E. Caux6, R. Cerulli2, S. Church7, P.E. Clegg4, A. Di,Gorgio5,2, I. Furniss8, T. Giannini2, W. Glencross8, C. Gry5,9, K. King10, T. Lim5, D. Lorenzetti11, S. Molinari5,2, D. Naylor12, R. Orfei2, P. Saraceno2, S. Sidher5, H. Smith4, L. Spinoglio2, B. Swinyard10, D. Texier5, E. Tommasi2, N. Trams5, and S. Unger10
1 Stockholm Observatory, S-133 36 Saltsjöbaden,
Received 2 July 1996 / Accepted 20 August 1996
Abstract. The first detection of thermal water emission from a Herbig-Haro object is presented. The observations were performed with the LWS (Long Wavelength Spectrograph) aboard ISO(Infrared Space Observatory). Besides H2O, rotational lines of CO are present in the spectrum of HH,54. These high-J CO lines are used to derive the physical model parameters of the FIR (far-infrared) molecular line emitting regions. This model fits simultaneously the observed OH and H2O spectra for an OH abundance X(OH) = 10-6 and a water vapour abundance X(H2O) = 10-5.
At a distance of 250,pc, the total CO, OH and H Orotational line cooling rate is estimated to be 1.3 10-2L , which is comparable to the mechanical luminosity generated by the 10 km s-1 shocks, suggesting that practically all of the cooling of the weak-shock regions is done by these three molecular species alone.
Key words: stars: formation - ISM: molecules - ISM: jets and outflows - ISM: individual objects: HH,54 - physical processes: shock waves - physical processes: radiative transfer
* Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA (see: Kessler et al. 1996).
Last change: December 16, 1996