Physical Conditions, Grain Temperatures, and Enhanced Very Small Grains in the Barnard Loop

Details Physical Conditions, Grain Temperatures, and Enhanced Very Small Grains in the Barnard Loop Physical Conditions, Grain Temperatures, and Enhanced Very Small Grains in the Barnard Loop

2000-01-03

arxiv.org/abs/astro-ph/0001024v1

Astronomy and Astrophysics

Astrophysics

21 pages, 6 figures. Accepted by Astrophysical Journal

Scientific paper

10.1086/308935

We derive the radio spectral index of the Barnard Loop (BL) from large-scale radio surveys at four frequencies and find it to be a thermal source. We use the radio data together with H-alpha data to determine the electron temperature in BL, the lambda-Ori HII region, and a high-latitude filament; all of these regions are somewhat cooler than typical HII regions. We perform least squares fits of the DIRBE diffuse IR intensities to the 21-cm line and radio continuum intensities. After the resolution of a ``geometrical conundrum'', this allows us to derive the electron density n_e; we find n_e ~ 2.0 cm^{-3} and pressure (P/k) ~ 24000 cm^{-3} K. Grains within BL are warmer than in HI regions. Trapped L-alpha accounts for the extra heating that is required. This is a general effect that needs to be accounted for in all analyses that examine IR emission from H^+ regions. Very small grains that emit 60 micron radiation are enhanced in BL relative to HI by a factor of 2-3, while PAH's that emit 12 micron are probably deficient by a factor ~2.

Affiliated with

Also associated with

No associations

Rating

Physical Conditions, Grain Temperatures, and Enhanced Very Small Grains in the Barnard Loop 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 Physical Conditions, Grain Temperatures, and Enhanced Very Small Grains in the Barnard Loop, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Physical Conditions, Grain Temperatures, and Enhanced Very Small Grains in the Barnard Loop will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-109941