THE HDO/H{sub 2}O RATIO IN GAS IN THE INNER REGIONS OF A LOW-MASS PROTOSTAR

Journal Article · Mon Dec 20 04:00:00 EST 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/725/2/L172· OSTI ID:21454888

Joergensen, Jes K ^[1]

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1. Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Oester Voldgade 5-7, DK-1350 Copenhagen K. (Denmark)

The HDO/H{sub 2}O abundance ratio is thought to be a key diagnostic for the evolution of water during the star and planet formation process and thus for its origin on Earth. We here present millimeter-wavelength high angular resolution observations of the deeply embedded protostar NGC 1333-IRAS4B from the Submillimeter Array targeting the 3{sub 12}-2{sub 21} transition of HDO at 225.6 GHz (E{sub u} = 170 K). We do not (or only very tentatively) detect the HDO line toward the central protostar, contrasting the previous prominent detection of a line from another water isotopologue, H{sup 18}{sub 2}O, with similar excitation properties using the IRAM Plateau de Bure Interferometer. The non-detection of the HDO line provides a direct, model-independent, upper limit to the HDO/H{sub 2}O abundance ratio of 6 x 10{sup -4} (3{sigma}) in the warm gas associated with the central protostar. This upper limit suggests that the HDO/H{sub 2}O abundance ratio is not significantly enhanced in the inner {approx}50 AU around the protostar relative to what is seen in comets and Earth's oceans and does not support previous suggestions of a generally enhanced HDO/H{sub 2}O ratio in these systems.

• OSTI ID: 21454888
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 725; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
COMETS
DEUTERIUM COMPOUNDS
EVOLUTION
FREQUENCY RANGE
GHZ RANGE
GHZ RANGE 100-1000
HEAVY WATER
HYDROGEN COMPOUNDS
INTERFEROMETERS
MEASURING INSTRUMENTS
OXYGEN COMPOUNDS
PLANETS
PROTOPLANETS
STAR EVOLUTION
STARS
WATER