Abundant H2D+ in the pre-stellar core L1544
Preprint
- 5 April 2003
Abstract
We have detected the 372 GHz line of ortho-H2D+ towards the pre-stellar core L1544. The strongest emission (T_mb ~ 1 K) occurs at the peak of the millimeter continuum emission, while measurements at offset positions indicate that H2D+ is confined within ~ 20 arcsec, where CO is highly depleted. The derived H2D+ abundance of ~ 10^{-9} is comparable with previous estimates of the electron abundance in the core, which suggests that H2D+ is the main molecular ion in the central 20 arcsec (2800 AU) of L1544. This confirms the expectations that H2D+ is dramatically enhanced in gas depleted of molecules other than H2. The measured abundance even exceeds the present model predictions by about a factor ten. One possibility is that all CNO-bearing neutral species, including atomic oxygen, are almost completely (> 98%) frozen within a radius of ~2800 AU.Keywords
All Related Versions
- Version 1, 2003-04-05, ArXiv
- Published version: Astronomy & Astrophysics, 403 (3), L37.
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