Anomalous phenomena in cyclopropenylidene (c-C3H2) with accurate collisional rate coefficients

Abstract

ABSTRACT Collisional rate coefficients are important parameters, but their calculation is a tedious task. Accurate collisional rate coefficients for collisional transitions between pure rotational levels of cyclopropenylidene (c-C3H2), colliding with He atom, are now available. Strong anomalous absorption line 220–211 at 21.587 GHz of cyclopropenylidene is found ubiquitous in interstellar medium. It is therefore worth to analyse the line spectrum of c-C3H2 using accurate collisional rate coefficients. After performing the Sobolev analysis of c-C3H2, we have found four anomalous absorption lines namely 22,0–21,1, 44,0–43,1, 33,0–32,1, and 43,2–50,5. We have also found two weak MASER lines, 40,4–33,1 and 51,4–44,1, which may make the detection of c-C3H2 in a cosmic object more convenient. Even for low kinetic temperature and low column density of cyclopropenylidene, the detection of 22,0–21,1 transition is possible, and it may be the reason for its detection in a large number of cosmic objects. The stability of results is tested.