COLD WATER VAPOR IN THE BARNARD 5 MOLECULAR CLOUD

• After more than 30 yr of investigations, the nature of gas-grain interactions at low temperatures remains an unresolved issue in astrochemistry. Water ice is the dominant ice found in cold molecular clouds; however, there is only one region where cold (similar to 10 K) water vapor has been detected-L1544. This study aims to shed light on ice desorption mechanisms under cold cloud conditions by expanding the sample. The clumpy distribution of methanol in dark clouds testifies to transient desorption processes at work-likely to also disrupt water ice mantles. Therefore, the Herschel HIFI instrument was used to search for cold water in a small sample of prominent methanol emission peaks. We report detections of the ground-state transition of o-H2O (J = 1(10)-1(01)) at 556.9360 GHz toward two positions in the cold molecular cloud, Barnard 5. The relative abundances of methanol and water gas support a desorption mechanism which disrupts the outer ice mantle layers, rather than causing complete mantle removal.

Subject headings

NATURVETENSKAP  -- Fysik -- Fusion, plasma och rymdfysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Fusion, Plasma and Space Physics (hsv//eng)

Keyword

DENSE CLOUDS

WAVE-ASTRONOMY-SATELLITE

stars: formation

ISM: molecules

RADIATIVE-TRANSFER

P603

astrochemistry

HERSCHEL

ISM: individual objects (Barnard 5)

ASAD SS

Astronomy & Astrophysics

V267

CORES

CH3OH

ASTROPHYSICAL JOURNAL

ROTATIONAL-EXCITATION

EMISSION

submillimeter: ISM

LINE OBSERVATIONS

1983

STAR-FORMING REGIONS

Publication and Content Type

art (subject category)

ref (subject category)