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

Abstract

We characterize an uncatalogued bright-rimmed cloud located at the border of the infrared dust bubble CN20 with the aim of investigating triggered star formation. In order to do this, we carried out radio continuum observations at 8.9 GHz using the Jansky Very Large Array (JVLA) interferometer with a synthesized beam size of 13 arcsec x 5 arcsec, and molecular observations using the Atacama Submillimeter Telescope Experiment (ASTE) at the (CO)-C-13 J = 3-2 and CS J = 7-6 transitions. An analysis of the molecular observations and of Herschel public data revealed the presence of a warm and dense clump with T-dus similar to 25 K and n(H-2) similar to 3 x 10(5) cm(3). The high angular resolution and sensitivity of the new radio continuum data revealed an arc-like radio filament in excellent correspondence with the illuminated border of the bright-rimmed cloud. This ionized boundary layer has an electron density of 176 cm(3). The spatial distribution of the young stellar object candidates probably related to the bright-rimmed cloud does not show clear evidence of a triggered origin. Finally, based on the evaluation of the pressure balance between the ionized and molecular gas, we conclude that the ionization front has stalled at the surface of the clump.