The structure of hot gas in Cepheus B

TL;DR

This study maps the hot gas structure in Cepheus B using SOFIA observations, revealing photon-dominated regions and local effects of star formation without global dynamical impact.

Contribution

It provides detailed spatial and spectral analysis of hot gas and PDRs in Cepheus B, combining SOFIA data with ground-based observations to understand star formation processes.

Findings

Detection of large PDRs at the cloud surface caused by OB star radiation.

Identification of bright internal PDRs around young stars indicating local compression.

No evidence of global dynamical influence on dense molecular material.

Abstract

By observing radiation-affected gas in the Cepheus B molecular cloud we probe whether the sequential star formation in this source is triggered by the radiation from newly formed stars. We used the dual band receiver GREAT onboard SOFIA to map [C II] and CO 13--12 and 11--10 in Cep B and compared the spatial distribution and the spectral profiles with complementary ground-based data of low-$J$ transitions of CO isotopes, atomic carbon, and the radio continuum. The interaction of the radiation from the neighboring OB association creates a large photon-dominated region (PDR) at the surface of the molecular cloud traced through the photoevaporation of C^+. Bright internal PDRs of hot gas are created around the embedded young stars, where we detect evidence of the compression of material and local velocity changes; however, on the global scale we find no indications that the dense molecular material is dynamically affected.