Search Publications
The PAH Emission Characteristics of the Reflection Nebula NGC 2023
Wolfire, Mark G.; Peeters, Els; Tielens, Alexander G. G. M. +3 more
We present 5-20 µm spectral maps of the reflection nebula NGC 2023 obtained with the Infrared Spectrograph SL and SH modes on board the Spitzer Space Telescope, which reveal emission from polycyclic aromatic hydrocarbons (PAHs), C60, and H2 superposed on a dust continuum. We show that several PAH emission bands correlat…
Polycyclic Aromatic Hydrocarbons in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars
Seok, Ji Yeon; Li, Aigen
A distinct set of broad emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 µm, is often detected in protoplanetary disks (PPDs). These features are commonly attributed to polycyclic aromatic hydrocarbons (PAHs). We model these emission features in the infrared spectra of 69 PPDs around 14 T Tauri and 55 Herbig Ae/Be stars in terms of as…
η Carinae's Dusty Homunculus Nebula from Near-infrared to Submillimeter Wavelengths: Mass, Composition, and Evidence for Fading Opacity
Hillier, D. John; Gull, Theodore R.; Nielsen, Krister +5 more
Infrared observations of the dusty, massive Homunculus Nebula around the luminous blue variable η Carinae are crucial to characterize the mass-loss history and help constrain the mechanisms leading to the great eruption. We present the 2.4-670 µm spectral energy distribution, constructed from legacy Infrared Space Observatory observations an…
HIFI Spectroscopy of H2O Submillimeter Lines in Nuclei of Actively Star-forming Galaxies
Menten, K. M.; van der Werf, P.; Stutzki, J. +10 more
We present a systematic survey of multiple velocity-resolved H2O spectra using Herschel/Heterodyne Instrument for the Far Infrared (HIFI) toward nine nearby actively star-forming galaxies. The ground-state and low-excitation lines (E up ≤ 130 K) show profiles with emission and absorption blended together, while absorption-fre…
Polycyclic Aromatic Hydrocarbon Emission in Spitzer/IRS Maps. II. A Direct Link between Band Profiles and the Radiation Field Strength
Peeters, E.; Stock, D. J.
We decompose the observed 7.7 µm polycyclic aromatic hydrocarbon (PAH) emission complexes in a large sample of over 7000 mid-infrared spectra of the interstellar medium using spectral cubes observed with the Spitzer/IRS-SL instrument. In order to fit the 7.7 µm PAH emission complex we invoke four Gaussian components, which are found to…
Observational Evidence Linking Interstellar UV Absorption to PAH Molecules
Behar, Ehud; Brosch, Noah; Tielens, Alexander G. G. M. +2 more
The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, …
ALMA Multiple-transition Molecular Line Observations of the Ultraluminous Infrared Galaxy IRAS 20551-4250: Different HCN, HCO+, and HNC Excitation, and Implications for Infrared Radiative Pumping
Imanishi, Masatoshi; Izumi, Takuma; Nakanishi, Kouichiro
We present our ALMA multi-transition molecular line observational results for the ultraluminous infrared galaxy IRAS 20551-4250, which is known to contain a luminous buried active galactic nucleus and shows detectable vibrationally excited (v 2 = 1f) HCN and HNC emission lines. The rotational J = 1-0, 4-3, and 8-7 of HCN, {HCO}}+
Search for Hydrogenated C60 (Fulleranes) in Circumstellar Envelopes
Zhang, Yong; Kwok, Sun; Sadjadi, SeyedAbdolreza +1 more
The recent detection of fullerene (C60) in space and the positive assignment of five diffuse interstellar bands to {{{C}}}60+ reinforce the notion that fullerene-related compounds can be efficiently formed in circumstellar envelopes and be present in significant quantities in the interstellar medium. Experimental s…
Hot Molecular Gas in the Circumnuclear Disk
Togi, Aditya; Mills, Elisabeth A. C.; Kaufman, Michael
We present an analysis of archival Infrared Space Observatory observations of H2 for three 14\prime\prime × 20\prime\prime pointings in the central 3 pc of the Galaxy: toward the southwest region and northeast region of the Galactic center circumnuclear disk (CND), and toward the supermassive black hole Sgr A*. We …
The Abundance of C2H4 in the Circumstellar Envelope of IRC+10216
Hinkle, K. H.; Cernicharo, J.; Fonfría, J. P. +3 more
High spectral resolution mid-IR observations of ethylene ({{{C}}}2{{{H}}}4) toward the AGB star IRC+10216 were obtained using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF). 80 ro-vibrational lines from the 10.5 µm vibrational mode {ν }7 with J ≲ 30 were de…