Search Publications
Universal bolometric corrections for active galactic nuclei over seven luminosity decades
Maiolino, R.; Fiore, F.; Bianchi, S. +12 more
Context. The AGN bolometric correction is a key element for understanding black hole (BH) demographics and computing accurate BH accretion histories from AGN luminosities. However, current estimates still differ from each other by up to a factor of two to three, and rely on extrapolations at the lowest and highest luminosities.
Aims: Here we …
Observations of Disequilibrium CO Chemistry in the Coldest Brown Dwarfs
Fortney, Jonathan J.; Marley, Mark S.; Freedman, Richard S. +10 more
Cold brown dwarfs are excellent analogs of widely separated, gas giant exoplanets, and provide insight into the potential atmospheric chemistry and physics we may encounter in objects to be discovered by future direct imaging surveys. We present a low-resolution, R ∼ 300, M-band spectroscopic sequence of seven brown dwarfs with effective temperatu…
Probing the size and charge of polycyclic aromatic hydrocarbons
Peeters, E.; Maragkoudakis, A.; Ricca, A.
We present a new method to accurately describe the ionization fraction and the size distribution of polycyclic aromatic hydrocarbons (PAHs) within astrophysical sources. To this purpose, we have computed the mid-infrared emission spectra of 308 PAH molecules of varying sizes, symmetries, and compactness, generated in a range of radiation fields. W…
The NASA Ames PAH IR Spectroscopic Database: The Laboratory Spectra
Boersma, C.; Allamandola, L. J.; Peeters, E. +7 more
The astronomical emission features, formerly known as the unidentified infrared bands, are now commonly ascribed to polycyclic aromatic hydrocarbons (PAHs). The laboratory experiments and computational modeling performed at NASA Ames Research Center generated a collection of PAH IR spectra that have been used to test and refine the PAH model. Thes…
Detection of PAH Absorption and Determination of the Mid-infrared Diffuse Interstellar Extinction Curve from the Sight Line toward Cyg OB2-12
Draine, B. T.; Hensley, Brandon S.
The sight line toward the luminous blue hypergiant Cyg OB2-12 is widely used to study interstellar dust on account of its large extinction (AV ≃ 10 mag) and the fact that this extinction appears to be dominated by dust typical of the diffuse interstellar medium. We present a new analysis of archival Infrared Space Observatory Short Wave…
Revisiting the Impact of Dust Production from Carbon-rich Wolf-Rayet Binaries
Sakon, Itsuki; Williams, Peredur M.; Lau, Ryan M. +3 more
We present a dust spectral energy distribution (SED) and binary stellar population analysis revisiting the dust production rates (DPRs) in the winds of carbon-rich Wolf-Rayet (WC) binaries and their impact on galactic dust budgets. DustEM SED models of 19 Galactic WC "dustars" reveal DPRs of ${\dot{M}}_{d}\sim {10}^{-10}\mbox{--}{10}^{-6}$ M⊙…
Temperature profiles of young disk-like structures. The case of IRAS 16293A
van Dishoeck, Ewine F.; Jørgensen, Jes K.; van 't Hoff, Merel L. R. +1 more
Context. Temperature is a crucial parameter in circumstellar disk evolution and planet formation because it governs the resistance of the gas to gravitational instability and sets the chemical composition of the planet-forming material.
Aims: We set out to determine the gas temperature of the young disk-like structure around the Class 0 proto…
Crystalline silicate absorption at 11.1 µm: ubiquitous and abundant in embedded YSOs and the interstellar medium
Wright, Christopher M.; Fujiyoshi, Takuya; Siebenmorgen, Ralf +5 more
Utilizing several instruments on 4-8 m telescopes, we have observed a large sample of objects in the mid-infrared (8-13 µm). These comprise a few evolved stars, multiple envelopes of embedded young stellar objects (YSOs) or compact H-II regions, and several sightlines through the interstellar medium (ISM). The latter is where dust resides - …
Surveying the Giant H II Regions of the Milky Way with SOFIA. II. M17
Lim, Wanggi; De Buizer, James M.; Radomski, James T.
We present our second set of results from our mid-infrared imaging survey of Milky Way giant H II regions. We used the FORCAST instrument on the Stratospheric Observatory For Infrared Astronomy (SOFIA) to obtain 20 and 37 µm images of the central ∼10' × 10' area of M17. We investigate the small- and large-scale properties of M17 using our da…
Resolving Decades of Periodic Spirals from the Wolf-Rayet Dust Factory WR 112
Moffat, Anthony F. J.; Stevens, Ian R.; Sakon, Itsuki +9 more
WR 112 is a dust-forming carbon-rich Wolf-Rayet (WC) binary with a dusty circumstellar nebula that exhibits a complex asymmetric morphology, which traces the orbital motion and dust formation in the colliding winds of the central binary. Unraveling the complicated circumstellar dust emission around WR 112 therefore provides an opportunity to under…