Search Publications
A Young Protoplanet Candidate Embedded in the Circumstellar Disk of HD 100546
Amara, Adam; Meyer, Michael R.; Girard, Julien H. +3 more
We present high-contrast observations of the circumstellar environment of the Herbig Ae/Be star HD 100546. The final 3.8 µm image reveals an emission source at a projected separation of 0.''48 ± 0.''04 (corresponding to ~47 ± 4 AU) at a position angle of 8.°9 ± 0.°9. The emission appears slightly extended with a point source component with a…
Embedded Protostars in the Dust, Ice, and Gas In Time (DIGIT) Herschel Key Program: Continuum SEDs, and an Inventory of Characteristic Far-infrared Lines from PACS Spectroscopy
Herczeg, Gregory J.; Lee, Jeong-Eun; Dunham, Michael M. +18 more
We present 50-210 µm spectral scans of 30 Class 0/I protostellar sources, obtained with Herschel-PACS, and 0.5-1000 µm spectral energy distributions, as part of the Dust, Ice, and Gas in Time Key Program. Some sources exhibit up to 75 H2O lines ranging in excitation energy from 100 to 2000 K, 12 transitions of OH, and CO rot…
The Structure, Origin, and Evolution of Interstellar Hydrocarbon Grains
Tielens, A. G. G. M.; Chiar, J. E.; Ricca, A. +1 more
Many materials have been considered for the carrier of the hydrocarbon absorption bands observed in the diffuse interstellar medium (ISM). In order to refine the model for ISM hydrocarbon grains, we analyze the observed aromatic (3.28, 6.2 µm) and aliphatic (3.4 µm) hydrocarbon absorption features in the diffuse ISM along the line of s…
Unidentified Infrared Emission Bands: PAHs or MAONs?
Zhang, Yong; Kwok, Sun
We suggest that the carrier of the unidentified infrared emission (UIE) bands is an amorphous carbonaceous solid with mixed aromatic/aliphatic structures, rather than free-flying polycyclic aromatic hydrocarbon molecules. Through spectral fittings of the astronomical spectra of the UIE bands, we show that a significant amount of the energy is emit…
Fossil Imprint of a Powerful Flare at the Galactic Center along the Magellanic Stream
Sutherland, Ralph S.; Bland-Hawthorn, J.; Maloney, Philip R. +1 more
The Fermi satellite discovery of the gamma-ray emitting bubbles extending 50° (10 kpc) from the Galactic center has revitalized earlier claims that our Galaxy has undergone an explosive episode in the recent past. We now explore a new constraint on such activity. The Magellanic Stream is a clumpy gaseous structure free of stars trailing behind the…
The Excitation of HCN and HCO+ in the Galactic Center Circumnuclear Disk
Morris, M. R.; Mills, E. A. C.; Güsten, R. +1 more
We present new observations of HCN and HCO+ in the circumnuclear disk (CND) of the Galaxy, which we obtained with the Atacama Pathfinder Experiment telescope. We mapped emission in rotational lines of HCN J = 3-2, 4-3, and 8-7, as well as of HCO+ J = 3-2, 4-3, and 9-8. We also present spectra of H13CN J = 3-2 and 4…
Curved Walls: Grain Growth, Settling, and Composition Patterns in T Tauri Disk Dust Sublimation Fronts
Hernández, J.; Watson, D. M.; Sargent, B. +6 more
The dust sublimation walls of disks around T Tauri stars represent a directly observable cross-section through the disk atmosphere and midplane. Their emission properties can probe the grain size distribution and composition of the innermost regions of the disk, where terrestrial planets form. Here we calculate the inner dust sublimation wall prop…
Deuterated Molecules in Orion KL from Herschel/HIFI
Bergin, Edwin A.; Neill, Justin L.; Crockett, Nathan R. +2 more
We present a comprehensive study of the deuterated molecules detected in the fullband HIFI survey of the Orion Kleinmann-Low nebula (Orion KL) region. Ammonia, formaldehyde, and methanol and their singly deuterated isotopologues are each detected through numerous transitions in this survey with a wide range in optical depths and excitation conditi…
The Detection of C60 in the Well-characterized Planetary Nebula M1-11
Meixner, M.; Otsuka, Masaaki; Yanagisawa, K. +4 more
We performed multiwavelength observations of the young planetary nebula (PN) M1-11 and obtained its elemental abundances, dust mass, and the evolutionary status of the central star. The AKARI/IRC, VLT/VISIR, and Spitzer/IRS spectra show features due to carbon-rich dust, such as the 3.3, 8.6, and 11.3 µm features due to polycyclic aromatic hy…
Evolution of the Stratospheric Temperature and Chemical Composition over One Titanian Year
Coustenis, Athena; Teanby, N. A.; Flasar, F. M. +11 more
Since the Voyager 1 (V1) flyby in 1980, Titan's exploration from space and the ground has been ongoing for more than a full revolution of Saturn around the Sun (one Titanian year or 29.5 Earth years had elapsed in 2010 May). In this study, we search for temporal variations affecting Titan's atmospheric thermal and chemical structure within that ye…