Abstract

Contributed Talk - Splinter LowMet

Friday, 13 September 2024, 17:25   (S23)

First detection of the CII 158 micron line in Draco

N. Schneider, V. Ossenkopf-Okada, E. Keilmann et al.
I. Physik. Insitut, University of Cologne

We report the first detection of the [CII] 158 micron line using upGREAT on SOFIA in the high-latitude, intermediate-velocity cloud Draco. There are no [CII] detections in clouds with similar (column) density and low FUV field (up to a few Habing), namely Spider, Polaris, and Musca. To understand the excitation conditions of the gas in Draco, we analyzed complementary CO and HI data, along with dust column density and temperature maps from Herschel, using RADEX and KOSMA-tau PDR modeling. The observed intensities can not be explained by UV-heated gas. Moreover, it suggest the presence of shocks in Draco that heat the gas and subsequently emit in the [CII] cooling line. These shocks are likely caused by the fast cloud’s motion toward the Galactic plane that is accompanied by collisions between HI clouds. We suggest that highly dynamic processes can be necessary for [CII] excitation in UV-faint low-density regions.