Study of a bright-rimmed cloud at the border of the infrared dust bubble CN20

Abstract

We characterize an uncatalogued bright-rimmed cloud located onto the border of the infrared dust bubble CN20 in order to investigate triggered star formation. To do this, we carried out radio continuum observations at 8.9 GHz with the Jansky Very Large Array (JVLA) interferometer with a synthesized beam of 13′′× 5′′, and molecular observations using the Atacama Submillimeter Telescope Experiment (ASTE) in the 12CO J=3?2 and CS J=7?6 transitions. The analysis of the molecular observations and Herschel public data reveals the presence of a warm and dense clump with Tdust 25 K and n(H2) 3 × 105 cm−3. The high angular resolution and sensitivity of the new radio continuum data have revealed an arc-like radio filament in excellent correspondence with the illuminated border of the bright-rimmed cloud. This ionised boundary layer has an electron density of 176 cm−3. The spatial distribution of the young stellar object candidates likely related to the bright-rimmed cloud does not show<br />a clear evidence of a triggered origin. Finally, based on the evaluation of the pressure balance between the ionised and molecular gas, we conclude that the ionisation front has stalled at the surface of the clump.