Search Publications
Laboratory measurements of cryogenic liquid alkane microwave absorptivity and implications for the composition of Ligeia Mare, Titan
Lorenz, Ralph D.; Lunine, Jonathan I.; Mitchell, Karl L. +2 more
The complex dielectric constants of liquids methane and ethane were measured at 90 K and 14.1 GHz, close to the frequency of the Cassini RADAR. The liquid ethane loss tangent is far greater than that of liquid methane, facilitating discrimination by remote sensing. The results suggest a methane-dominated composition for the northern sea, Ligeia Ma…
Local H i Emissivity Measured with Fermi-LAT and Implications for Cosmic-Ray Spectra
Casandjian, Jean-Marc
Cosmic-ray (CR) electrons and nuclei interact with the Galactic interstellar gas and produce high-energy γ-rays. The γ-ray emission rate per hydrogen atom, called emissivity, provides a unique indirect probe of the CR flux. We present the measurement and the interpretation of the emissivity in the solar neighborhood for γ-ray energy from 50 MeV to…
Lithospheric structure of Venus from gravity and topography
Ruiz, Javier; Jiménez-Díaz, Alberto; Kirby, Jon F. +3 more
There are many fundamental and unanswered questions on the structure and evolution of the venusian lithosphere, which are key issues for understanding Venus in the context of the origin and evolution of the terrestrial planets. Here we investigate the lithospheric structure of Venus by calculating its crustal and effective elastic thicknesses (T
Spatially Extended Na I D Resonant Emission and Absorption in the Galactic Wind of the Nearby Infrared-Luminous Quasar F05189-2524
Veilleux, Sylvain; Rupke, David S. N.
Emission from metal resonant lines has recently emerged as a potentially powerful probe of the structure of galactic winds at low and high redshift. In this work, we present only the second example of spatially resolved observations of Na i D emission from a galactic wind in a nearby galaxy (and the first 3D observations at any redshift). F05189-2…
Proper motions and kinematics of selected bulge globular clusters
Bonfanti, A.; Bica, E.; Barbuy, B. +2 more
We computed proper motions of a selected sample of globular clusters projected on the central bulge, employing CCD images gathered along the last 25 yr at the ESO-New Technology Telescope, ESO-Danish and Hubble Space Telescope telescopes. We presented a method to derive their proper motions, and a set of coordinate transformations to obtain 3D Gal…
An Extreme Starburst in the Core of a Rich Galaxy Cluster at z = 1.7
Muzzin, Adam; Smith, Matthew W. L.; Yee, H. K. C. +19 more
We have discovered an optically rich galaxy cluster at z = 1.7089 with star formation occurring in close proximity to the central galaxy. The system, SpARCS104922.6+564032.5, was detected within the Spitzer Adaptation of the red-sequence Cluster Survey, and confirmed through Keck-MOSFIRE spectroscopy. The rest-frame optical richness of Ngal
Kepler’s Supernova: An Overluminous Type Ia Event Interacting with a Massive Circumstellar Medium at a Very Late Phase
Maeda, Yoshitomo; Katsuda, Satoru; Petre, Robert +7 more
We have analyzed XMM-Newton, Chandra, and Suzaku observations of three similarly aged, ejecta-dominated supernova remnants (SNRs), Kepler's SNR, Tycho's SNR, and SNR 0509-67.5, to investigate the properties of the SN ejecta and the circumstellar medium (CSM). By simply comparing the X-ray spectra, we find that line intensity ratios of iron-group e…
How Important Are Electron Beams in Driving Chromospheric Evaporation in the 2014 March 29 Flare?
Krucker, Säm; Kleint, Lucia; Battaglia, Marina +1 more
We present high spatial resolution observations of chromospheric evaporation in the flare SOL2014-03-29T17:48. Interface Region Imaging Spectrograph observations of the Fe xxi λ 1354.1 line indicate evaporating plasma at a temperature of 10 MK along the flare ribbon during the flare peak and several minutes into the decay phase with upflow velocit…
A Radio-Polarisation and Rotation Measure Study of the Gum Nebula and Its Environment
Gaensler, B. M.; Carretti, E.; Bernardi, G. +7 more
The Gum Nebula is 36°-wide shell-like emission nebula at a distance of only ∼450 pc. It has been hypothesized to be an old supernova remnant, fossil H ii region, wind-blown bubble, or combination of multiple objects. Here we investigate the magneto-ionic properties of the nebula using data from recent surveys: radio-continuum data from the NRAO VL…
Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity
Guenther, E. W.; Zechmeister, M.; Hatzes, A. P. +14 more
Aims: We investigate the nature of the long-period radial velocity variations in α Tau first reported over 20 yr ago.
Methods: We analyzed precise stellar radial velocity measurements for α Tau spanning over 30 yr. An examination of the Hα and Ca II λ8662 spectral lines, and Hipparcos photometry was also done to help discern the nature o…