Discovery of interstellar N2

Molecular nitrogen (N-2) is the most abundant molecule in the Earth's atmosphere and in the less chemically-processed atmosphere of Titan. Until recently N-2 had never been detected in interstellar space. We report on the first detection of interstellar N-2 in the interstellar medium (ISM) toward the star HD 124314 with an observed fractional abundance of N-2/H-2 = 3.3 x 10(-7). This N-2 abundance is almost two orders of magnitude larger than expected from models of interstellar nitrogen chemistry for diffuse clouds and is also less than expected from dark cloud chemistry. Preliminary analysis of high signal to noise data on 20 Aql yields x(N-2) <= 4.7 x 10(-8), which is surprisingly low given that 20 Aql has a higher CN abundance. There appears to be an anticorrelation between N-2 and CN: Is this anti-correlation caused by differences in the predictions of diffuse and dark cloud chemistry? Further observations of interstellar N-2 are required to fully understand the implications for interstellar nitrogen chemistry.