EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 489/1 Article
Free access article

Issue A&A
Volume 489, Number 1, October I 2008
Page(s) 229 - 243
Section Interstellar and circumstellar matter
DOI http://dx.doi.org/10.1051/0004-6361:200810336
Published online 28 July 2008



A&A 489, 229-243 (2008)
DOI: 10.1051/0004-6361:200810336

Spatially resolved near-infrared spectroscopy of the massive star-forming region IRAS 19410+2336

N. L. Martín-Hernández1, A. Bik2, E. Puga3, 4, D. E. A. Nürnberger5, and L. Bronfman 
6

1  Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38205 La Laguna, Spain
    e-mail: leticia@iac.es
2  Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
3  Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
4  Departamento de Astrofísica Molecular e Infrarroja, Instituto de Estructura de la Materia, CSIC, Serrano 121, 29006 Madrid, Spain
5  European Southern Observatory, Casilla 19001, Santiago 19, Chile
6  Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile


Received 6 June 2008 / Accepted 24 July 2008 


Abstract
Aims. IRAS 19410+2336 is a young massive star forming region with an intense outflow activity. Outflows are frequently studied in the near-infrared (NIR) since the H2 emission in this wavelength range often traces the shocked molecular gas. However, the mechanisms behind the H2 emission detected in IRAS 19410+2336 have not been clarified yet. We present here spatially resolved NIR spectroscopy which allows us to verify whether the H2 emission originates from thermal emission in shock fronts or from fluorescence excitation by non-ionizing UV photons. Moreover, NIR spectroscopy also offers the possibility of studying the characteristics of the putative driving source(s) of the H2 emission by the detection of photospheric and circumstellar spectral features, and of the environmental conditions (e.g. extinction).
Methods. We obtained long-slit, intermediate-resolution, NIR spectra of IRAS 19410+2336 using LIRIS, the NIR imager/spectrographer mounted on the 4.2 m William Herschel Telescope. As a complement, we also obtained J, H and $K_{\rm s}$ images with the Las Campanas 2.5 m Du Pont Telescope, and archival mid-infrared (MIR) Spitzer images at 3.6, 4.5, 5.8 and 8.0 $\mu$m.
Results. We confirm the shocked nature of the H2 emission, with an excitation temperature of about 2000 K, based on the analysis of relevant H2 line ratios, ortho-to-para ratios and excitation diagrams. We have also identified objects with very different properties and evolutionary stages in IRAS 19410+2336. The most massive source at millimeter wavelengths, mm1, with a mass of a few tens of solar masses, has a bright NIR (and MIR) counterpart. This suggests that emission – probably coming through a cavity created by one of the outflows present in the region, or from the outflow cavity itself – is leaking at these wavelengths. The second most massive millimeter source, mm2, is only detected at $\lambda \ga$ 6 $\mu$m, suggesting that it could be a high-mass protostar still in its main accretion phase. The NIR spectra of some neighboring sources show CO first-overtone bandhead emission which is associated with neutral material located in the inner regions of the circumstellar environment of YSOs.


Key words: infrared: ISM -- ISM: individual objects: IRAS 19410+2336 -- stars: formation -- stars: early-type -- ISM: jets and outflows



© ESO 2008


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.