Search Publications
On the amount of heavy molecular ions in Titan's ionosphere
Gurnett, D. A.; Coates, A. J.; Garnier, P. +16 more
We present observational evidence that the ionosphere of Titan below an altitude of 1150 km is a significant source of heavy (>100 amu) molecular organic species. This study is based on measurements by five instruments (RPWS/LP, RPWS/E, INMS, CAPS/ELS, CAPS/IBS) onboard the Cassini spacecraft during three flybys (T17, T18, T32) of Titan. The io…
Deep XMM-Newton Spectroscopic and Timing Observations of the Isolated Radio Millisecond Pulsar PSR J0030+0451
Bogdanov, Slavko; Grindlay, Jonathan E.
We present deep XMM-Newton European Photon Imaging Camera spectroscopic and timing X-ray observations of the nearby solitary radio millisecond pulsar, PSR J0030+0451. Its emission spectrum in the 0.1-10 keV range is found to be remarkably similar to that of the nearest and best-studied millisecond pulsar, PSR J0437-4715, being well described by a …
Crater modification and geologic activity in Enceladus' heavily cratered plains: Evidence from the impact crater distribution
Schenk, Paul; Kirchoff, Michelle R.
Although we can observe current activity on Saturn's satellite Enceladus with Cassini, insight into past activity is best achieved (for now) through studying the impact crater distributions. Furthermore, approximation of terrain ages can only be attained through calculations using crater densities and estimations of impact rates in the saturnian s…
Eight-Dimensional Mid-Infrared/Optical Bayesian Quasar Selection
Brandt, W. N.; Myers, Adam D.; Schneider, Donald P. +11 more
We explore the multidimensional, multiwavelength selection of quasars from mid-infrared (MIR) plus optical data, specifically from Spitzer-Infrared Array Camera (IRAC) and the Sloan Digital Sky Survey (SDSS). Traditionally, quasar selection relies on cuts in two-dimensional color space despite the fact that most modern surveys (optical and IR) are…
The ACS Nearby Galaxy Survey Treasury. I. The Star Formation History of the M81 Outer Disk
de Jong, Roelof S.; Williams, Benjamin F.; Dolphin, Andrew +16 more
The Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury is a large Hubble Space Telescope (HST)/ACS treasury program to obtain resolved stellar photometry for a volume-limited sample of galaxies out to 4 Mpc. As part of this program, we have obtained deep ACS imaging of a field in the outer disk of the large spiral galaxy M81. The fiel…
A north-south difference in the rotation rate of auroral hiss at Saturn: Comparison to Saturn's kilometric radio emission
Gurnett, D. A.; Persoon, A. M.; Hospodarsky, G. B. +3 more
Broadband whistler-mode emissions, commonly observed by the Cassini spacecraft at high latitudes in Saturn's magnetosphere at frequencies below about 100 Hz, have characteristics very similar to auroral hiss observed at high latitudes in Earth's magnetosphere. In contrast to terrestrial auroral hiss, which shows no obvious rotational modulation, S…
The Roadmap for Unification in Galaxy Group Selection. I. A Search for Extended X-ray Emission in the CNOC2 Survey
Finoguenov, A.; Saglia, R. P.; Connelly, J. L. +6 more
X-ray properties of galaxy groups can unlock some of the most challenging research topics in modern extragalactic astronomy: the growth of structure and its influence on galaxy formation. Only with the advent of the Chandra and XMM-Newton facilities have X-ray observations reached the depths required to address these questions in a satisfactory ma…
Intermediate polars in the Swift/BAT survey: spectra and white dwarf masses
Greiner, J.; Ajello, M.; Osborne, J. +1 more
Context: White dwarf masses in cataclysmic variables are difficult to determine accurately, but are fundamental for understanding binary system parameters, as well as binary evolution.
Aims: We investigate the X-ray spectral properties of a sample of Intermediate Polars (IP) detected above 15 keV to derive the masses of their accreting white d…
X-Ray Cavities, Filaments, and Cold Fronts in the Core of the Galaxy Group NGC 5044
Buote, David A.; Brighenti, Fabrizio; Mathews, William G. +3 more
We present a two-dimensional analysis of the bright nearby galaxy group NGC 5044 using the currently available Chandra and XMM data. In the inner 10 kpc, a pair of cavities are evident together with a set of bright X-ray filaments. If the cavities are interpreted as gas displaced by relativistic plasma inflated by an active galactic nucleus, even …
The Temperature and Density Structure of the Solar Corona. I. Observations of the Quiet Sun with the EUV Imaging Spectrometer on Hinode
Warren, Harry P.; Brooks, David H.
Measurements of the temperature and density structure of the solar corona provide critical constraints on theories of coronal heating. Unfortunately, the complexity of the solar atmosphere, observational uncertainties, and the limitations of current atomic calculations, particularly those for Fe, all conspire to make this task very difficult. A cr…