Sh2-205 - I. The surrounding interstellar medium
Abstract
We investigate the distribution of the interstellar matter in the environs of the HII region Sh2-205, based on neutral hydrogen 21-cm-line data and radio continuum images at 408 and 1420 MHz obtained from the CGPS, 12CO (J=1 ->0) observations, high-resolution IRAS data (HIRES), and MSX data.
Sh2-205 can be separated into three distinct optical structures: SH149.25-0.0, SH148.83-0.67, and LBN148.11-0.45. The three regions are detected at both 408 and 1420 MHz. The derived spectral indices show the thermal nature of SH148.83-0.67 and LBN148.11-0.45. LBN148.11-0.45 is a classical HII region surrounded by an HI shell. The associated neutral atomic and ionized masses are 65Msolar and 70Msolar, respectively. Dust and molecular gas (~6 × 104Msolar) related to this ionized region have been found. In particular, a photodissociation region is detected at the interface between the ionized and molecular regions. If the proposed exciting star HD24094 were an O8-O9 type star, as suggested by its near-infrared colours, its UV photon flux would be strong enough to explain the ionization of the nebula. The optical, radio continuum, and 21-cm-line data allow us to conclude that SH148.83-0.67 is an interstellar bubble powered by the energetic action of HD24431. The associated neutral atomic and ionized masses are 180Msolar and 300Msolar, respectively. The emission of SH149.25-0.0 is too faint to derive the dust and gas parameters. An HI shell centred at (l, b) = (149°0', -1°30') was also identified. It correlates morphologically with the molecular gas emission. The neutral atomic and molecular masses of the shell are 1600Msolar and 2.6 × 104Msolar, respectively. The open cluster NGC1444 is probably responsible for shaping this HI structure.- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 2008
- DOI:
- 10.1111/j.1365-2966.2008.13117.x
- arXiv:
- arXiv:0802.2243
- Bibcode:
- 2008MNRAS.387.1080R
- Keywords:
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- stars: individual: HD24431;
- stars: individual: ALS7793;
- stars: individual: HD24094;
- ISM: bubbles;
- ISM: structure;
- Astrophysics
- E-Print:
- Accepted for publication in MNRAS. 10 figures and 6 tables