Search Publications
The Infrared Spectra of Very Large Irregular Polycyclic Aromatic Hydrocarbons (PAHs): Observational Probes of Astronomical PAH Geometry, Size, and Charge
Peeters, Els; Bauschlicher, Charles W., Jr.; Allamandola, Louis J.
The mid-infrared (IR) spectra of six large, irregular polycyclic aromatic hydrocarbons (PAHs) with formulae (C84H24-C120H36) have been computed using density functional theory (DFT). Trends in the dominant band positions and intensities are compared to those of large, compact PAHs as a function of geomet…
Abundant Circumstellar Silica Dust and SiO Gas Created by a Giant Hypervelocity Collision in the ~12 Myr HD172555 System
Bryden, G.; Wyatt, M. C.; Chen, C. H. +4 more
The fine dust detected by infrared (IR) emission around the nearby β Pic analog star HD172555 is very peculiar. The dust mineralogy is composed primarily of highly refractory, nonequilibrium materials, with approximately three quarters of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra (nonequili…
The Extended Environment of M17: A Star Formation History
Bieging, John H.; Kang, Miju; Indebetouw, Rémy +9 more
M17 is one of the youngest and most massive nearby star-formation regions in the Galaxy. It features a bright H II region erupting as a blister from the side of a giant molecular cloud (GMC). Combining photometry from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) with complementary infrared (IR) surveys, we identif…
Dust-Bounded Ultraluminous Infrared Galaxies: Model Predictions for Infrared Spectroscopic Surveys
Abel, N. P.; van Hoof, P. A. M.; Satyapal, S. +2 more
The observed faintness of infrared fine-structure line emission along with the warm far-infrared (FIR) colors of ultraluminous infrared galaxies (ULIRGs) is a long-standing problem. In this work, we calculate the line and continuum properties of a cloud exposed to an active galactic nucleus (AGN) and starburst spectral energy distribution. We use …
The Evolution Of Massive Young Stellar Objects in the Large Magellanic Cloud. I. Identification and Spectral Classification
Brandner, Wolfgang; Chu, You-Hua; Gruendl, Robert A. +5 more
We present and categorize Spitzer infrared spectrometer spectra of 294 objects in the Large Magellanic Cloud (LMC) to create the largest and most complete catalog of massive young stellar object (YSO) spectra in the LMC. Target sources were identified from infrared photometry and multiwavelength images indicative of young, massive stars highly ens…
Detection of Water Ice Grains on the Surface of the Circumstellar Disk Around HD 142527
Tamura, M.; Ishii, M.; Kudo, T. +11 more
Coronagraphic imaging for the Herbig Ae star, HD 142527, was performed using the Coronagraphic Imager with Adaptive Optics (CIAO) on the 8.2 m Subaru Telescope. The images were obtained in the H2O ice filter (λ = 3.08 µm) using adaptive optics (AO), and in the L' band without AO. Combining these data with previous observational re…
Spatially Resolved Spectroscopy of Sub-AU-Sized Regions of T Tauri and Herbig Ae/Be Disks
Najita, J.; Eisner, J. A.; Graham, J. R. +1 more
We present spatially resolved near-IR spectroscopic observations of 15 young stars. Using a grism spectrometer behind the Keck interferometer, we obtained an angular resolution of a few milliarcseconds and a spectral resolution of 230, enabling probes of both gas and dust in the inner disks surrounding the target stars. We find that the angular si…
Silicon Carbide Absorption Features: Dust Formation in the Outflows of Extreme Carbon Stars
Wheeler, Caleb H.; Speck, Angela K.; Corman, Adrian B. +2 more
Infrared carbon stars without visible counterparts are generally known as extreme carbon stars. We have selected a subset of these stars with absorption features in the 10-13 µm range, which has been tentatively attributed to silicon carbide (SiC). We add three new objects meeting these criterion to the seven previously known, bringing our t…
The Infrared Luminosity Functions of Rich Clusters
Rieke, George H.; Zabludoff, Ann I.; Rieke, Marcia J. +2 more
We present Multiband Imaging Photometer observations of the cluster A3266. About 100 spectroscopic cluster members have been detected at 24 µm. The infrared (IR) luminosity function (LF) in A3266 is very similar to that in the Coma cluster down to the detection limit L IR ~ 1043 erg s-1, suggesting a universa…
Revealing the Structure of a Pre-Transitional Disk: The Case of the Herbig F Star SAO 206462 (HD 135344B)
Ménard, F.; Apai, D.; Hamaguchi, K. +23 more
SAO 206462 (HD 135344B) has previously been identified as a Herbig F star with a circumstellar disk with a dip in its infrared excess near 10 µm. In combination with a low accretion rate estimated from Br γ, it may represent a gapped, but otherwise primordial or "pre-transitional" disk. We test this hypothesis with Hubble Space Telescope cor…