The molecular disk surrounding the protostellar binary L1551 IRS5

¹ ESA Astrophysics Mission Division, Research and Scientific Support Department, ESTEC, PO Box 299, 2200 AG Noordwijk, The Netherlands
² Centre for Astrophysics and Space Science at Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
³ Unit for Space Sciences and Astronomy, Physics Department, University of Kent, Canterbury CT2 7NR, UK

Corresponding author: C. V. M. Fridlund, Malcolm.Fridlund@esa.int

Received: 24 July 2001
Accepted: 23 October 2001

Abstract

The inner three arcminutes surrounding the Class 0/1 binary protostar L1551 IRS5 have been observed using the  transitions of the , , ¹²CO and ¹³CO molecular species. Since the line core of  is self reversed over a substantial part of our map, observations of isotopomers such as  are required in order to estimate the mass of the molecular gas in the immediate vicinity of IRS5. Our observations demonstrate the presence of a large (~7000 AU radius) dense, possibly rotating, molecular disk with a mass of a few  oriented perpendicular to the major axis of an extended molecular outflow. The disk is surrounded by an envelope with a radius of ~10 000 AU that contains two massive (each ~1 ) clumps. One of these features appears to be kinematically disconnected from both the disk and the molecular outflow.