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

Martín-Hernández, N. L.; Bik, A.; Puga, E.; Nürnberger, D. E. A.; Bronfman, L.
Bibliographical reference

Astronomy and Astrophysics, Volume 489, Issue 1, 2008, pp.229-243

Advertised on:
10
2008
Number of authors
5
IAC number of authors
1
Citations
20
Refereed citations
20
Description
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 Ks 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 μm. 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 λ ⪆ 6 μm, 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.
Related projects
Izquierda - Imagen RGB de la nebulosa de Orión y M43 obtenida filtros estrechos con la cámara WFC en el INT: H alfa (rojo), [S II] 6716+30 (verde), [O III] 5007 (azul). Derecha - Imagen en falso color de la nebulosa planetaria NGC 6778. En azul se ve la emisión en la línea de O II tomada con el filtro sintonizable azul del instrumento OSIRIS en el GTC; en verde imagen con el filtro estrecho de [O III] del Nordic Optical Telescope (NOT).
Physics of Ionized Nebulae
The research that is being carried out by the group can be condensed into two main lines: 1) Study of the structure, dynamics, physical conditions and chemical evolution of Galactic and extragalactic ionized nebulae through detailed analysis and modelization of their spectra. Investigation of chemical composition gradients along the disk of our
Jorge
García Rojas