A Magnetically Supported Photodissociation Region in M17

Astronomy and Astrophysics – Astronomy

Scientific paper

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

32

Ism: H Ii Regions, Ism: Atoms, Ism: Individual: Messier Number: M17, Ism: Magnetic Fields

Scientific paper

The southwestern (SW) part of the Galactic H II region M17 contains an obscured ionization front that is most easily seen at infrared and radio wavelengths. It is nearly edge-on, thus offering an excellent opportunity to study the way in which the gas changes from fully ionized to molecular as radiation from the ionizing stars penetrates into the gas. M17 is also one of the very few H II regions for which the magnetic field strength can be measured in the photodissociation region ( PDR) that forms the interface between the ionized and molecular gas. Here we model an observed line of sight through the gas cloud, including the H+, H0 (PDR), and molecular layers, in a fully self-consistent single calculation. An interesting aspect of the M17 SW bar is that the PDR is very extended. We show that the strong magnetic field that is observed to be present inevitably leads to a very deep PDR, because the structure of the neutral and molecular gas is dominated by magnetic pressure, rather than by gas pressure, as previously had been supposed. We also show that a wide variety of observed facts can be explained if a hydrostatic geometry prevails, in which the gas pressure from an inner X-ray hot bubble and the outward momentum of the stellar radiation field compress the gas and its associated magnetic field in the PDR, as has already been shown to occur in the Orion Nebula. The magnetic field compression may also amplify the local cosmic-ray density. The pressure in the observed magnetic field balances the outward forces, suggesting that the observed geometry is a natural consequence of the formation of a star cluster within a molecular cloud.

No associations

LandOfFree

Say what you really think

Search LandOfFree.com for scientists and scientific papers. Rate them and share your experience with other people.

Rating

A Magnetically Supported Photodissociation Region in M17 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 A Magnetically Supported Photodissociation Region in M17, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Magnetically Supported Photodissociation Region in M17 will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFWR-SCP-O-1682623

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.