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[Si II], [Fe II], [C II], and H2 Emission from Massive Star-forming Regions
Kaufman, Michael J.; Wolfire, Mark. G.; Hollenbach, David J.
We calculate the [Si II] 34.8 µm, [Fe II] 26.0 µm, and [C II] 158 µm infrared fine-structure emission that may arise from ionized gas (H II regions) and/or associated neutral gas (photodissociation regions [PDRs]) in massive star-forming regions. Assuming thermal pressure balance between an H II region and a PDR, the relative amo…
Pixie Dust: The Silicate Features in the Diffuse Interstellar Medium
Tielens, A. G. G. M.; Chiar, J. E.
We have analyzed the 9.7 and ``18'' µm interstellar silicate absorption features along the line of sight toward four heavily extincted galactic WC-type Wolf-Rayet (WR) stars. We construct two interstellar extinction curves from 1.25 to 25 µm using near-IR extinction measurements from the literature, along with the silicate profiles of …
Nearby Debris Disk Systems with High Fractional Luminosity Reconsidered
Apai, D.; Derekas, A.; Ábrahám, P. +5 more
By searching the IRAS and ISO databases, we compiled a list of 60 debris disks that exhibit the highest fractional luminosity values (fd>10-4) in the vicinity of the Sun (d<120 pc). Eleven out of these 60 systems are new discoveries. Special care was taken to exclude bogus disks from the sample. We computed the fraction…
Mid-Infrared Spectral Diagnostics of Nuclear and Extranuclear Regions in Nearby Galaxies
Helou, G.; Moustakas, J.; Roussel, H. +19 more
Mid-infrared diagnostics are presented for a large portion of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from ISO and Spitzer. The SINGS data set includes low- and high-resolution spectral maps and broadband imaging in the infrared for over 160 nuclear and extranuclear regions within 75 nearby galaxies spanning a…
Detection of the 205 µm [N II] Line from the Carina Nebula
Stark, A. A.; Stacey, G. J.; Oberst, T. E. +7 more
We report the first detection of the 205 µm 3P1-->3P0 [N II] line from a ground-based observatory using a direct detection spectrometer. The line was detected from the Carina star formation region using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) on the Antarctic Submillimeter Telescope and R…
Mid-Infrared Spectroscopy of Carbon Stars in the Small Magellanic Cloud
Price, S. D.; Wood, P. R.; Matsuura, M. +3 more
We have observed a sample of 36 objects in the Small Magellanic Cloud (SMC) with the Infrared Spectrometer on the Spitzer Space Telescope. Nineteen of these sources are carbon stars. An examination of the near- and mid-infrared photometry shows that the carbon-rich and oxygen-rich dust sources follow two easily separated sequences. A comparison of…
Neon and Oxygen Abundances in M33
Massey, Philip; Garnett, Donald R.; Jacoby, George +1 more
We present new spectroscopic observations of 13 H II regions in the Local Group spiral galaxy M33. The regions observed range from 1 to 7 kpc in distance from the nucleus. Of the 13 H II regions observed, the [O III] λ4363 line was detected in six regions. Electron temperatures were thus able to be determined directly from the spectra using the [O…
Outflows from Massive Young Stellar Objects as Seen with the Infrared Array Camera
Smith, Howard A.; Marengo, M.; Hora, J. L. +1 more
The bipolar outflow from the massive star-forming cluster in DR 21 is one of the most powerful known, and in IRAC images the outflow stands out by virtue of its brightness at 4.5 µm (band 2). Indeed, IRAC images of many Galactic and extragalactic star formation regions feature prominent band 2 morphologies. We have analyzed archival ISO SWS …
Discovery of a Population of Pre-Main-Sequence Stars in NGC 346 from Deep Hubble Space Telescope ACS Images
Tosi, M.; Sabbi, E.; Nota, A. +9 more
We report the discovery of a rich population of low-mass stars in the young, massive NGC 346 star-forming region in the Small Magellanic Cloud from deep V, I, and Hα images taken with the Hubble Space Telescope Advanced Camera for Surveys. These stars have likely formed together with the NGC 346 cluster, ~=3-5 Myr ago. Their magnitudes and colors …
Ultraviolet-to-Far-Infrared Properties of Local Star-forming Galaxies
Giavalisco, M.; Leitherer, C.; Armus, L. +5 more
We present the results of a multiwavelength study of nearby galaxies aimed at understanding the relation between the ultraviolet and far-infrared emission in star-forming galaxies. The data set comprises new ultraviolet (from HST STIS), ground-based Hα, and radio continuum observations, together with archival infrared data (from IRAS and ISO). The…