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The Absence of Crystalline Silicates in the Diffuse Interstellar Medium
Tielens, A. G. G. M.; Kemper, F.; Vriend, W. J.
Infrared spectroscopy provides a direct handle on the composition and structure of interstellar dust. We have studied the dust along the line of sight toward the Galactic center using Short Wavelength Spectrometer data obtained with the Infrared Space Observatory (ISO). We focused on the wavelength region from 8 to 13 µm, which is dominated …
The Profiles of the 3-12 Micron Polycyclic Aromatic Hydrocarbon Features
Hony, S.; Tielens, A. G. G. M.; Allamandola, L. J. +4 more
We present spectra of the 3.3 µm and 11.2 µm polycyclic aromatic hydrocarbon (PAH) features of a large number of stellar sources, planetary nebulae, reflection nebulae, H II regions, and galaxies, obtained with Infrared Space Observatory Short Wavelength Spectrometer. Clear variations are present in the profiles of these features. Most…
The Far-Infrared Spectrum of Arp 220
Cernicharo, José; Smith, Howard A.; González-Alfonso, Eduardo +1 more
Infrared Space Observatory Long Wavelength Spectrometer grating observations of the ultraluminous infrared galaxy Arp 220 shows absorption in molecular lines of OH, H2O, CH, NH, and NH3, as well as in the [O I] 63 µm line and emission in the [C II] 158 µm line. We have modeled the continuum and the emission/absorp…
The Far-Infrared Spectrum of the Sagittarius B2 Region: Extended Molecular Absorption, Photodissociation, and Photoionization
Cernicharo, José; Goicoechea, Javier R.; Rodríguez-Fernández, Nemesio J.
We present large-scale 9'×27' (~25pc×70pc) far-IR observations around Sgr B2 using the Long-Wavelength Spectrometer (LWS) on board the Infrared Space Observatory (ISO). The spectra are dominated by the strong continuum emission of dust, the widespread molecular absorption of light hydrides (OH, CH, and H2O), and th…
Polycyclic Aromatic Hydrocarbon Emission in the 15-21 Micron Region
Allamandola, L. J.; Peeters, E.; Mattioda, A. L. +1 more
Observations from the Spitzer Space Telescope have drawn attention to spectroscopic structure longward of 15 µm that is associated with objects showing prominent unidentified infrared (UIR) bands in the mid-IR. If polycyclic aromatic hydrocarbons (PAHs) are indeed responsible for the UIR features, longer wavelength emission arising from out-…
Deuterated Interstellar Polycyclic Aromatic Hydrocarbons
Tielens, A. G. G. M.; Allamandola, L. J.; Peeters, E. +3 more
We report infrared spectral evidence of deuterated interstellar polycyclic aromatic hydrocarbons (PAHs). Two bands are detected in the infrared emission from the ionization bar in Orion at 4.4 and 4.65 µm. The one at 4.65 µm is present at the 4.4 σ level, while the one at 4.4 µm is more tentative, with a σ equal to 1.9. An emissi…
The Mid-Infrared Luminosity Function of Galaxies in the European Large Area Infrared Space Observatory Survey Southern Fields
Pozzi, F.; Franceschini, A.; Serjeant, S. +7 more
We present the first determination of the 15 µm luminosity function of galaxies from the European Large Area ISO Survey (ELAIS) southern fields. We have adopted a new criterion to separate the quiescent, nonevolving and the starburst, evolving populations based on the ratio of mid-infrared to optical luminosity. Strong evolution is suggested…
On the Measurement of Elemental Abundance Ratios in Inner Galaxy H II Regions
Rubin, Robert H.; Haas, Michael R.; Colgan, Sean W. J. +2 more
Although variations in elemental abundance ratios in the Milky Way certainly exist, details remain uncertain, particularly in the inner Galaxy, where stars and H II regions in the Galactic plane are obscured optically. In this paper we revisit two previously studied, inner Galaxy H II regions: G333.6-0.2 and W43. We observed three new positions in…
Observations of Cold Dust in Nearby Elliptical Galaxies
Kuno, Nario; Haas, Martin; Sansom, Anne E. +2 more
Spectral energy distribution (SED) analyses that include new millimeter to far-infrared (FIR) observations obtained with continuum instruments on the Nobeyama and James Clerk Maxwell Telescopes and the Infrared Space Observatory are presented for seven nearby (<45 Mpc) FIR-bright elliptical galaxies. These are analyzed together with archival FI…
Reconsidering the Origin of the 21 Micron Feature: Oxides in Carbon-rich Protoplanetary Nebulae?
Mutschke, H.; Posch, Th.; Andersen, A.
The origin of the so-called 21 µm feature that is especially prominent in the spectra of some carbon-rich protoplanetary nebulae (PPNs) is the matter of a lively debate. A large number of potential band carriers have been presented and discarded within the past decade. This paper gives an overview of the problems related to the hitherto prop…