Evidence for inward motion in a galactic cirrus core

Using the IRAM 30 m radiotelescope a dense core in MCLD 123.5+24.9 has been observed in the CS (J=2-->1), (3-->2) and (5-->4) lines. In the lower two rotational lines the cloud extends over 0.03 pc x 0.15 pc at an adopted dis tance of 150 pc. The core harbours three dense condensations with full widt hs at half maximum between 4500 and 6100 AU. Based on (CO)-O-18 observation s their masses are estimated to be between 0.06 and 0.12 M.. The southernmo st shows asymmetric self-absorbed CS (2-->1) and (3-->2) lines with the blu e shifted part brighter than the red shifted; the velocity of the (5-->4) t ransition is in between the blue and red shifted lines of the lower transit ions. These features are well-tested diagnostics of inward motion in molecu lar clouds. An inward velocity of 4 to 10 m s(-1) is estimated from the CS lines.