DESPOTIC — A New Software Library to Derive the Energetics and SPectra of Optically Thick Interstellar Clouds
I describe DESPOTIC, a code to Derive the Energetics and SPectra of Optically Thick Interstellar Clouds. DESPOTIC represents such clouds using a one-zone model, and can calculate line luminosities, line cooling rates, and in restricted cases line profiles using an escape probability formalism. It also includes approximate treatments of the other dominant heating and cooling processes for the cold interstellar medium, including cosmic ray and X-ray heating, grain photoelectric heating, heating of the dust by infrared and ultraviolet radiation, thermal cooling of the dust, and collisional energy exchange between dust and gas. Based on these heating and cooling rates, DESPOTIC can calculate clouds’ equilibrium gas and dust temperatures, and their time-dependent thermal evolution. The software is intended to allow rapid and interactive calculation of clouds’ characteristic temperatures, identification of their dominant heating and cooling mechanisms, and prediction of their observable spectra across a wide range of interstellar environments. DESPOTIC is implemented as a Python package, and is released under the GNU General Public License.