Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

The ionizing sources of luminous compact HII regions in the RCW106 and RCW122 clouds

J. M. C. Grave, M. S. N. Kumar, D. K. Ojha, G. D. C. Teixeira, G. Pace

Abstract
Context. Given the rarity of young O star candidates, compact HII regions embedded in dense molecular cores continue to serve as potential sites for peering into the details of high-mass star formation.
Aims. We uncover the ionizing sources of the most luminous and compact HII regions embedded in the RCW106 and RCW122 giant molecular clouds, known to be relatively nearby (2-4 kpc) and isolated, thus providing an opportunity to examine spatial scales of a few hundred to a thousand AU in size.
Methods. High spatial resolution (0.3''), mid-infrared spectra (R = 350), including the fine structure lines [ArIII] and [NeII], were obtained for four luminous compact HII regions embedded inside the dense cores within the RCW106 and RCW122 molecular cloud complexes. At this resolution, these targets reveal point-like sources surrounded by the nebulosity of different morphologies, thereby uncovering details at spatial dimensions of <1000?AU. The point-like sources display [ArIII] and [NeII] lines – the ratios of which are used to estimate the effective temperature of the embedded sources.
Results. The derived temperatures are indicative of mid-late O type objects for all the sources with [ArIII] emission. Previously known characteristics of these targets from the literature, including evidence of disk or accretion, suggest that the identified sources may grow more to become early-type O stars by the end of the star formation process.

Keywords
stars: formation – HII regions – infrared: stars

Astronomy and Astrophysics
Volume 563, Page A123_1
March 2014

>> PDF>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website