Volume 489, Number 3, October III 2008
|Page(s)||1189 - 1200|
|Section||Interstellar and circumstellar matter|
|Published online||25 August 2008|
A mid-infrared study of H II regions in the Magellanic Clouds: N88 A and N160 A
Instituto de Astrofisíca de Canarias, Vía Láctea s/n, 38205 La Laguna, Spain e-mail: email@example.com
2 NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA
3 SETI Institute, 515 N. Whisman Road, Mountain View, CA 94043, USA
4 Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada
5 NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035, USA
Accepted: 6 August 2008
Aims. To show the importance of high-spatial resolution observations of H II regions when compared with observations obtained with larger apertures such as ISO, we present mid-infrared spectra of two Magellanic Cloud H II regions, N88 A and N160 A.
Methods. We obtained mid-infrared ( μm), long-slit spectra with TIMMI2 on the ESO 3.6 m telescope. These are combined with archival spectra obtained with the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope, and are compared with the low-spatial resolution ISO-SWS data. An inventory of the spectra in terms of atomic fine-structure lines and molecular bands is presented.
Results. Concerning N88 A, an isolated H II region with no adjacent infrared sources, the observations indicate that the line fluxes observed by ISO-SWS and Spitzer-IRS come exclusively from the compact H II region of about 3´´ in diameter. This is not the case for N160 A, which has a more complex morphology. We have spectroscopically isolated for the first time the individual contributions of the three components of N160 A, two high-excitation blobs, A1 and A2, and the young stellar object (YSO) N160 A-IR. In addition, extended [S IV] emission is observed with TIMMI2 and is most likely associated with the central star cluster located between A1 and A2. We show the value of these high-spatial resolution data in determining source characteristics, such as the degree of ionization of each high-excitation blob or the bolometric luminosity of the YSO. This luminosity (2105 ) is about one order of magnitude lower than previously estimated. For each high-excitation blob, we also determine the electron density and the elemental abundances of Ne, S, and Ar.
Key words: ISM: lines and bands / ISM: dust, extinction / ISM: H II regions / ISM: individual objects: N88A / infrared: ISM / ISM: individual objects: N160A
© ESO, 2008
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