Search Publications
An Initial Mass Function Study of the Dwarf Starburst Galaxy NGC 4214
O'Connell, R. W.; Calzetti, D.; Kennicutt, R. C. +11 more
The production rate of ionizing photons in young (<=8 Myr), unresolved stellar clusters in the nearby irregular galaxy NGC 4214 is probed using multi-wavelength Hubble Space Telescope WFC3 data. We normalize the ionizing photon rate by the cluster mass to investigate the upper end of the stellar initial mass function (IMF). We have found that w…
The evolution of H I and C IV quasar absorption line systems at 1.9 < z < 3.2
Carswell, R. F.; Kim, T. -S.; Partl, A. M. +1 more
We have investigated the distribution and evolution of ~3100 intergalactic neutral hydrogen (H i) absorbers with H I column densities log NH I = [12.75,17.0] at 1.9 < z < 3.2, using 18 high resolution, high signal-to-noise quasar spectra obtained from the ESO VLT/UVES archive. We used two sets of Voigt profile fitting analysis, on…
NeMars: An empirical model of the martian dayside ionosphere based on Mars Express MARSIS data
Sánchez-Cano, B.; Witasse, O.; Radicella, S. M. +2 more
Several models of the martian ionosphere have been developed in the last years. In this paper, a new empirical model for the dayside electron density of the martian ionosphere (primary and secondary layer), called NeMars, is described. The model is mainly based on MARSIS AIS data (Active Ionospheric Sounding from the Mars Advanced Radar and Ionosp…
Herschel Far-infrared Spectroscopy of the Galactic Center. Hot Molecular Gas: Shocks versus Radiation near Sgr A*
Contursi, A.; Lis, D. C.; Bell, T. A. +10 more
We present a ~52-671 µm spectral scan toward Sgr A* taken with the PACS and SPIRE spectrometers on board Herschel. The achieved angular resolution allows us to separate, for the first time at far-IR wavelengths, the emission toward the central cavity (gas in the inner central parsec of the galaxy) from that of the surrounding circumnuclear d…
The Self-similarity of the Circumgalactic Medium with Galaxy Virial Mass: Implications for Cold-mode Accretion
Kacprzak, Glenn G.; Churchill, Christopher W.; Nielsen, Nikole M. +1 more
We apply halo abundance matching to obtain galaxy virial masses, M h, and radii, R vir, for 183 "isolated" galaxies from the "Mg II Absorber-Galaxy Catalog." All galaxies have spectroscopic redshifts (0.07 <= z <= 1.12) and their circumgalactic medium (CGM) is probed in Mg II absorption within projected galactocentric …
The closest black holes
Maccarone, T. J.; Heywood, I.; Fender, R. P.
Starting from the assumption that there is a large population (≥108) of stellar-mass isolated black holes (IBH) distributed throughout our Galaxy, we consider the detectable signatures of accretion from the interstellar medium (ISM) that may be associated with such a population. We simulate the nearby (radius 250 pc) part of this popula…
Data Reduction and Early Science Calibration for FORCAST, A Mid-Infrared Camera for SOFIA
Schoenwald, J.; Wang, J.; Vacca, W. D. +7 more
FORCAST is a mid-infrared (5-40 µm) facility instrument for the Stratospheric Observatory for Infrared Astronomy (SOFIA). After achieving first light flight in 2010 May, FORCAST has completed two observatory characterization flights and thirteen science flights on SOFIA. In this paper we describe the photometric calibration of FORCAST which …
Morphology of fluvial networks on Titan: Evidence for structural control
Black, Benjamin A.; Perron, J. Taylor; Burr, Devon M. +2 more
Although Titan’s surface shows clear evidence of erosional modification, such as fluvial incision, evidence for tectonism has been less apparent. On Earth, fluvial networks with strongly preferred orientations are often associated with structural features, such as faults or joints, that influence flow or erodibility. We delineated and classified t…
Predictions of Ion Production Rates and Ion Number Densities within the Diamagnetic Cavity of Comet 67P/Churyumov-Gerasimenko at Perihelion
Vigren, E.; Galand, M.
We present a one-dimensional ion chemistry model of the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko, the target comet for the ESA Rosetta mission. We solve the continuity equations for ionospheric species and predict number densities of electrons and selected ions considering only gas-phase reactions. We apply the model to the subsolar d…
The Hubble Space Telescope Treasury Program on the Orion Nebula Cluster
Panagia, N.; Robberto, M.; Scandariato, G. +27 more
The Hubble Space Telescope (HST) Treasury Program on the Orion Nebula Cluster (ONC) has used 104 orbits of HST time to image the Great Orion Nebula region with the Advanced Camera for Surveys (ACS), the Wide-Field/Planetary Camera 2 (WFPC2), and the Near-Infrared Camera and Multi-Object Spectrograph (NICMOS) instrument in 11 filters ranging from t…