DI in the outer Galaxy
| dc.creator | Chengalur, Jayaram N. | |
| dc.creator | Braun, Robert | |
| dc.creator | Burton, W. Butler | |
| dc.date | 1997-01-13 | |
| dc.date.accessioned | 2026-07-07T02:22:41Z | |
| dc.date.available | 2026-07-07T02:22:41Z | |
| dc.description | We report on a deep search with the Westerbork Synthesis Radio Telescope towards the galactic anticenter for the 327 MHz hyperfine transition of DI. This is a favorable direction for a search because: (i) the HI optical depth is high due to velocity crowding; (ii) the observed molecular column density is low (implying that most of the deuterium would probably be in atomic form, rather than in HD); and (iii) the stellar reprocessing should be minimal. Our observations are about a factor of two more sensitive than previous searches for DI in this direction. We detect a low significance (about 4 sigma) feature, consistent in both amplitude and center frequency with an emission feature reported previously (Blitz & Heiles 1987). If this is the DI line, then the implied N_D/N_H of 3.9+/-1.0 x 10^-5 is comparable to the inferred pre-solar deuterium abundance. Our observation is consistent with the recent low measurements of D/H towards high-redshift Lyman-limit systems. On the other hand, if the reports of high DI abundance (about 24 x 10^-5) in such systems are confirmed, then our observations imply that even in regions of reduced star formation within the outer Galaxy, the DI abundance has been reduced by a factor of about 6 from the primordial abundance. | |
| dc.description | 4 page LaTeX requires l-aa.sty and psfig.sty, 1 ps figure. Accepted for publication in A&A Letters | |
| dc.identifier | https://arxiv.org/abs/astro-ph/9701057 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/9701057 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/10965 | |
| dc.subject | Astrophysics | |
| dc.title | DI in the outer Galaxy | |
| dc.type | text |