Detection of (NNH+)-N-15 in L1544

作者：Bizzocchi L^*; Caselli P; Dore L

来源：Astronomy & Astrophysics, 2010, 510: L5.

DOI：10.1051/0004-6361/200913835

• ISM: clouds
• ISM: molecules
• ISM: individual object: L1544
• radio lines: ISM

Context. Excess levels of N-15 isotopes which have been detected in primitive solar system materials are explained as a remnant of interstellar chemistry which took place in regions of the protosolar nebula.
Aims. Chemical models of nitrogen fractionation in cold clouds predict an enhancement in the gas-phase abundance of N-15-bearing molecules, thus we have searched for N-15 variants of the N2H+ ion in L1544, which is one of the best candidate sources for detection owing to its low central core temperature and high CO depletion.
Methods. With the IRAM 30m telescope we have obtained deep integrations of the (NNH+)-N-15 (1-0) line at 91.2 GHz.
Results. The (NNH+)-N-15 (1-0) line has been detected toward the dust emission peak of L1544. The N-14/N-15 abundance ratio in (NNH+)-N-15 resulted 446 +/- 71, very close to the protosolar value of similar to 450, higher than the terrestrial ratio of similar to 270, and significantly lower than the lower limit in L1544 found by Gerin et al. (2009, ApJ, 570, L101) in the same object using ammonia isotopologues.

• 出版日期2010-2