Astron. Astrophys. 344, L9-L12 (1999)

Letter to the Editor

Shocked molecular hydrogen from RNO 91

M.S. NandaKumar ¹, B.G. Anandarao ¹ and C.J. Davis <sup>2

1</sup> Physical Research Laboratory, Navrangpura, Ahmedabad, 380009 - India (nanda@prl.ernet.in,anand@prl.ernet.in)
² Joint Astronomy Center, 660 N. A'ohoku Place, University Park, Hilo, HI 96720, USA (cdavis@jach.hawaii.edu)

Received 18 November 1998 / Accepted 18 February 1999

Abstract

We report the detection of the H₂ =1-0 S(1) line at 2.122 µm, from RNO 91 in the L43 dark cloud, which is known to be a T Tauri star surrounded by a 1700AU disk structure (containing ices) and a weak outflow. The non-detection of the H₂ =2-1 S(1) line at 2.247 µm suggests shock excitation rather than fluorescence. The emission is extended spatially up to 9" in the north-south direction. The line intensity peak (FWHM 3") corresponds to the star RNO 91 which is embedded in a cocoon of gas and dust. The observed H₂ emission from this cocoon may be attributed to embedded Herbig-Haro like knots. The H₂ line flux in the central is estimated to be ergs sec^-1 cm^{- 2}, which indicates a mass flow rate of yr^-1. Furthermore, narrow band image taken through H₂ 1-0 S(1) filter is presented, which reveal a tilted disk and bipolar outflow structure that agrees with earlier observations and models. We show that this disk/outflow system is a unique case.

Key words: stars: formation stars: pre-main sequence ISM: Herbig-Haro objects ISM: jets and outflows infrared: stars accretion, accretion disks

Send offprint requests to: M.S. Nanda Kumar

SIMBAD Objects

Contents

• 1. Introduction
• 2. Observations and data reduction
• 3. Results
• 4. Discussion
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: March 10, 1999
helpdesk.link@springer.de