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

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 2(20)-2(11) 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 2(2,0)-2(1,1), 4(4,0)-4(3,1), 3(3,0)-3(2,1), and 4(3,2)-5(0,5). We have also found two weak MASER lines, 4(0,4)-3(3,1) and 5(1,4)-4(4,1), 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 2(2,0)-2(1,1) 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.