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http://hdl.handle.net/20.500.12386/24043
Titolo: | Bipolar H II regions - Morphology and star formation in their vicinity. I. G319.88+00.79 and G010.32-00.15 | Autori: | Deharveng, L. Zavagno, A. Samal, M. R. Anderson, L. D. LeLeu, G. Brevot, D. Duarte-Cabral, A. MOLINARI, Sergio Pestalozzi, M. Foster, J. B. Rathborne, J. M. Jackson, J. M. |
Data pubblicazione: | 2015 | Rivista: | ASTRONOMY & ASTROPHYSICS | Numero: | 582 | Da pagina:: | A1 | Abstract: | Aims: Our goal is to identify bipolar H ii regions and to understand their morphology, their evolution, and the role they play in the formation of new generations of stars. Methods: We use the Spitzer-GLIMPSE, -MIPSGAL, and Herschel-Hi-GAL surveys to identify bipolar H ii regions, looking for (ionized) lobes extending perpendicular to dense filamentary structures. We search for their exciting star(s) and estimate their distances using near-IR data from the 2MASS or UKIDSS surveys. Dense molecular clumps are detected using Herschel-SPIRE data, and we estimate their temperature, column density, mass, and density. MALT90 observations allow us to ascertain their association with the central H ii region (association based on similar velocities). We identify Class 0/I young stellar objects (YSOs) using their Spitzer and Herschel-PACS emissions. These methods will be applied to the entire sample of candidate bipolar H ii regions to be presented in a forthcoming paper. Results: This paper focuses on two bipolar H ii regions, one that is especially interesting in terms of its morphology, G319.88+00.79, and one in terms of its star formation, G010.32-00.15. Their exciting clusters are identified and their photometric distances estimated to be 2.6 kpc and 1.75 kpc, respectively; thus G010.32-00.15 (known as W31 north) lies much closer than previously assumed. We suggest that these regions formed in dense and flat structures that contain filaments. They have a central ionized region and ionized lobes extending perpendicular to the parental cloud. The remains of the parental cloud appear as dense (more than) and cold (14-17 K) condensations. The dust in the photodissociation regions (in regions adjacent to the ionized gas) is warm (19-25 K). Dense massive clumps are present around the central ionized region. G010.32-00.14 is especially remarkable because five clumps of several hundred solar masses surround the central H ii region; their peak column density is a few, and the mean density in their central regions reaches several. Four of them contain at least one massive YSO (including an ultracompact H ii region and a high-luminosity Class I YSO); these clumps also contain extended green objects (EGOs) and Class II methanol masers. This morphology suggests that the formation of a second generation of massive stars has been triggered by the central bipolar H ii region. It occurs in the compressed material of the parental cloud. Appendices are available in electronic form at <A href="http://www.aanda.org/10.1051/0004-6361/201423835/olm">http://www.aanda.org | URI: | http://hdl.handle.net/20.500.12386/24043 | URL: | http://arxiv.org/abs/1507.00215v1 https://www.aanda.org/articles/aa/abs/2015/10/aa23835-14/aa23835-14.html |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201423835 | Bibcode ADS: | 2015A&A...582A...1D | Fulltext: | open |
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