The Post-Shock Chemical Lifetimes of Outflow Tracers and a Possible New Mechanism to Produce Water Ice Mantles

Details The Post-Shock Chemical Lifetimes of Outflow Tracers and a Possible New Mechanism to Produce Water Ice Mantles The Post-Shock Chemical Lifetimes of Outflow Tracers and a Possible New Mechanism to Produce Water Ice Mantles

1998-03-30

arxiv.org/abs/astro-ph/9803330v1

Astrophys.J.499:777-792,1998

Astronomy and Astrophysics

Astrophysics

31 pages (including 16 figures), using aas2pp4.sty. To be published in ApJ, June 1 1998 issue

Scientific paper

10.1086/305656

We have used a coupled time-dependent chemical and dynamical model to investigate the lifetime of the chemical legacy left in the wake of C-type shocks. We concentrate this study on the chemistry of H2O and O2, two molecules which are predicted to have abundances that are significantly affected in shock-heated gas. Two models are presented: (1) a three-stage model of pre-shock, shocked, and post-shock gas; and (2) a Monte-Carlo cloud simulation where we explore the effects of stochastic shock activity on molecular gas over a cloud lifetime. In agreement with previous studies, we find that shock velocities in excess of 10 km s^-1 are required to convert all of the oxygen not locked in CO into H2O before the gas has an opportunity to cool. For pure gas-phase models the lifetime of the high water abundances, or ``H2O legacy'', in the post-shock gas is 4 - 7 x 10^5 years. Through the Monte Carlo cloud simulation we demonstrate that the time-average abundance of H2O is a sensitive function of the frequency of shocks. Thus we predict that the abundance of H2O and other known outflow tracers can be used to trace the history of shock activity in molecular gas. For gas-grain models we find that the abundance of water-ice on grain surfaces can be quite large and is comparable to that observed in molecular clouds. This offers a possible alternative method to create water mantles without resorting to grain surface chemistry: gas heating and chemical modification due to a C-type shock and subsequent depletion of the gas-phase species onto grain mantles.

Affiliated with

Also associated with

No associations

Rating

The Post-Shock Chemical Lifetimes of Outflow Tracers and a Possible New Mechanism to Produce Water Ice Mantles 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 The Post-Shock Chemical Lifetimes of Outflow Tracers and a Possible New Mechanism to Produce Water Ice Mantles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Post-Shock Chemical Lifetimes of Outflow Tracers and a Possible New Mechanism to Produce Water Ice Mantles will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-110659