Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2012-03-09
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
Scientific paper
Context: We analyze the NGC 2024 HII region and molecular cloud interface using [12CII] and [13CII] observations. Aims: We attempt to gain insight into the physical structure of the interface layer between the molecular cloud and the HII region. Methods. Observations of [12CII] and [13CII] emission at 158 {\mu}m with high spatial and spectral resolution allow us to study the detailed structure of the ionization front and estimate the column densities and temperatures of the ionized carbon layer in the PDR. Results: The [12CII] emission closely follows the distribution of the 8 mum continuum. Across most of the source, the spectral lines have two velocity peaks similar to lines of rare CO isotopes. The [13CII] emission is detected near the edge-on ionization front. It has only a single velocity component, which implies that the [12CII] line shape is caused by self-absorption. An anomalous hyperfine line-intensity ratio observed in [13CII] cannot yet be explained. Conclusions: Our analysis of the two isotopes results in a total column density of N(H)~1.6\times10^23 cm^-2 in the gas emitting the [CII] line. A large fraction of this gas has to be at a temperature of several hundred K. The self-absorption is caused by a cooler (T<=100 K) foreground component containing a column density of N(H)~10^22 cm^-2.
Colgan Sean W. J.
Graf Urs U.
Guan Xiaoxu
Güsten Rolf
Hartogh R.
No associations
LandOfFree
[12CII] and [13CII] 158 mum emission from NGC 2024: Large column densities of ionized carbon 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 [12CII] and [13CII] 158 mum emission from NGC 2024: Large column densities of ionized carbon, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and [12CII] and [13CII] 158 mum emission from NGC 2024: Large column densities of ionized carbon will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-301989