Upper limits to interstellar NH+and para-NH2−abundances

New upper limits on the interstellar O 2 abundance

We report new observations of molecular oxygen in absorption at z = 0.685 in front of the radio source B0218+357. The lines at 56.3 and 118.7 GHz have been observed, redshifted to 33.4 and 70.5 GHz respectively, with the 12m at Kitt Peak, 43m at Green Bank telescopes, and the 45m Nobeyama radio telescope. Deriving the surface filling factor of the absorbing dark cloud with other lines detected ...

Limits on Interstellar Messages

Upper limits to interstellar NH + and para - NH − 2 abundances Herschel - HIFI observations towards Sgr B 2 ( M ) and G 10 . 6 − 0 .

The understanding of interstellar nitrogen chemistry has improved significantly with recent results from the Herschel Space Observatory. To set even better constraints, we report here on deep searches for the NH ground state rotational transition J = 1.5−0.5 of the Π1/2 lower spin ladder, with fine-structure transitions at 1013 and 1019 GHz, and the para-NH2 11,1−00,0 rotational transition at 9...

Ortho-to-para ratio of interstellar heavy water*

Context. Despite the low elemental deuterium abundance in the Galaxy, enhanced molecular D/H ratios have been found in the environments of low-mass star-forming regions, and in particular the Class 0 protostar IRAS 16293-2422. Aims. The CHESS (Chemical HErschel Surveys of Star forming regions) key program aims to study the molecular complexity of the interstellar medium. The high sensitivity an...

Upper limits on the probability of an interstellar civilization arising in the local Solar neighborhood

At this point in time, there is very little empirical evidence on the likelihood of a space-faring species originating in the biosphere of a habitable world. However, there is a tension between the expectation that such a probability is relatively high (given our own origins on Earth), and the lack of any basis for believing the Solar System has ever been visited by an extraterrestrial coloniza...