Methanol maps of low-mass protostellar systems: the Serpens Molecular Core

Details Methanol maps of low-mass protostellar systems: the Serpens Molecular Core Methanol maps of low-mass protostellar systems: the Serpens Molecular Core

2010-04-13

arxiv.org/abs/1004.2217v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

Accepted for publication in A&A.

Scientific paper

Observations of Serpens have been performed at the JCMT using Harp-B. Maps over a 4.5'x5.4' region were made in a frequency window around 338 GHz, covering the 7-6 transitions of methanol. Emission is extended over each source, following the column density of H2 but showing up also particularly strongly around outflows. The rotational temperature is low, 15-20 K, and does not vary with position within each source. The abundance is typically 10^-9 - 10^-8 with respect to H2 in the outer envelope, whereas "jumps" by factors of up to 10^2 -10^3 inside the region where the dust temperature exceeds 100 K are not excluded. A factor of up to ~ 10^3 enhancement is seen in outflow gas. In one object, SMM4, the ice abundance has been measured to be ~ 3x10^-5 with respect to H2 in the outer envelope, i.e., a factor of 10^3 larger than the gas-phase abundance. Comparison with C18O J=3-2 emission shows that strong CO depletion leads to a high gas-phase abundance of CH3OH not just for the Serpens sources, but for a larger sample of protostars. The observations illustrate the large-scale, low-level desorption of CH3OH from dust grains, extending out to and beyond 7500 AU from each source, a scenario which is consistent with non-thermal (photo-)desorption from the ice. The observations also illustrate the usefulness of CH3OH as a tracer of energetic input in the form of outflows, where methanol is sputtered from the grain surfaces. Finally, the observations provide further evidence of CH3OH formation through CO hydrogenation proceeding on grain surfaces in low-mass envelopes.

Affiliated with

Also associated with

No associations

Rating

Methanol maps of low-mass protostellar systems: the Serpens Molecular Core does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Methanol maps of low-mass protostellar systems: the Serpens Molecular Core, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methanol maps of low-mass protostellar systems: the Serpens Molecular Core will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-282683