Document 
| Abstract | PDF (431 KB) | PS (341 KB) | References | HTML | Online Material | Simbad Objects | NASA ADS Abstract Service |
A&A 458, 417-426 (2006)
DOI: 10.1051/0004-6361:20065187
Probing isotopic ratios at z = 0.89: molecular line absorption in front of the quasar PKS 1830-211
S. Muller1, 2, M. Guélin2, M. Dumke3, 2, R. Lucas2 and F. Combes41 Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), PO Box 23-141, 106 Taipei, Taiwan
e-mail: muller@asiaa.sinica.edu.tw
2 Institut de RadioAstronomie Millimétrique (IRAM), 300 rue de la piscine, 38406 St-Martin-d'Hères, France
3 European Southern Observatory (ESO), Alonso de Cordova 3107, Casilla 19001, Santiago 19, Chile
4 Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France
(Received 13 March 2006 / Accepted 26 July 2006 )
Abstract
With the Plateau de Bure interferometer, we have measured
the C, N, O and S isotopic abundance ratios in the arm of a spiral
galaxy with a redshift of 0.89. The galaxy is seen face-on according
to HST images. Its bulge intercepts the line of sight to the
radio-loud quasar
PKS 1830-211
, giving rise at mm wavelengths to two
Einstein images located each behind a spiral arm. The arms appear in
absorption in the lines of several molecules, giving the opportunity
to study the chemical composition of a galaxy only a few Gyr old. The
isotopic ratios in this spiral galaxy differ markedly from those
observed in the Milky Way. The 17O/18O and 14N/15N
ratios are low, as one would expect from an object too young to let
low mass stars play a major role in the regeneration of the gas.
Key words: quasars: individual: PKS 1830-211 -- quasars: absorption lines -- astrochemistry -- galaxies: ISM -- abundances -- ISM: molecules -- ISM: abundances
© ESO 2006