Search Publications
Electrical properties of Titan's surface from Cassini RADAR scatterometer measurements
Cassini RADAR Team; Lorenz, Ralph D.; Ostro, Steven J. +4 more
We report regional-scale low-resolution backscatter images of Titan's surface acquired by the Cassini RADAR scatterometer at a wavelength of 2.18-cm. We find that the average angular dependence of the backscatter from large regions and from specific surface features is consistent with a model composed of a quasi-specular Hagfors term plus a diffus…
First X-Ray Observations of the Young Pulsar J1357-6429
Zavlin, Vyacheslav E.
The first short Chandra and XMM-Newton observations of the young and energetic pulsar J1357-6429 provided indications of a tail-like pulsar wind nebula associated with this object as well as pulsations of its X-ray flux with a pulsed fraction pf>~50% and a thermal component dominating at energies E<~2 keV. The putative nebula is v…
Ram Pressure Stripping of an Isolated Local Group Dwarf Galaxy: Evidence for an Intragroup Medium
McConnachie, Alan W.; Venn, Kim A.; Young, Lisa M. +2 more
We compare the stellar structure of the isolated, Local Group dwarf galaxy Pegasus (DDO 216) with low-resolution H I maps from L. M. Young et al. Our comparison reveals that Pegasus displays the characteristic morphology of ram pressure stripping; in particular, the H I has a ``cometary'' appearance that is not reflected in the regular, elliptical…
Vector Spectropolarimetry of Dark-cored Penumbral Filaments with Hinode
Lites, B. W.; Ichimoto, K.; Bellot Rubio, L. R. +9 more
We present spectropolarimetric measurements of dark-cored penumbral filaments taken with Hinode at a resolution of 0.3". Our observations demonstrate that dark-cored filaments are more prominent in polarized light than in continuum intensity. Far from disk center, the Stokes profiles emerging from these structures are very asymmetric and show evid…
Two SMC Symbiotic Stars Undergoing Steady Hydrogen Burning
Zezas, A.; Munari, U.; Orio, M. +2 more
Two symbiotic stars in the Small Magellanic Cloud (SMC), Lin 358 and SMC 3, have been supersoft X-ray sources (SSSs) for more than 10 years. We fit atmospheric and nebular models to their X-ray, optical, and UV spectra obtained at different epochs. The X-ray spectra are extremely soft and appear to be emitted by the white dwarf atmosphere, not by …
Virial Masses of Black Holes from Single Epoch Spectra of Active Galactic Nuclei
Bechtold, Jill; Kelly, Brandon C.
We describe the general problem of estimating black hole masses of active galactic nuclei (AGNs) by calculating the conditional probability distribution of MBH given some set of observables. Special attention is given to the case where one uses the AGN continuum luminosity and emission line widths to estimate MBH, and we outl…
Stellar Populations of Globular Clusters in the Elliptical Galaxy NGC 1407
Forbes, Duncan A.; Brodie, Jean P.; Beasley, Michael A. +2 more
We present high-quality Keck spectroscopic data for a sample of 20 globular clusters (GCs) in the massive E0 galaxy NGC 1407. A subset of 20 line-strength indices of the Lick/IDS system has been measured for both the GC system and the central integrated starlight of the galaxy. Ages, metallicities, and [α/Fe] ratios have been derived using several…
Forward Modeling of Hot Loop Oscillations Observed by SUMER and SXT
Erdélyi, R.; Wang, T. J.; Bradshaw, S. J. +1 more
An example of hot active region loop oscillations observed by SUMER and SXT is presented. The hypothesis that a fundamental mode standing slow sausage (acoustic) wave is initiated by a footpoint microflare is tested and confirmed using a forward modeling approach. The oscillation is set up immediately after the heating pulse. The duration, tempora…
Electron conductivity and density profiles derived from the mutual impedance probe measurements performed during the descent of Huygens through the atmosphere of Titan
Berthelier, J. J.; Rodrigo, R.; López-Moreno, J. J. +15 more
During the descent of the Huygens probe through the atmosphere of Titan, on January 14th, 2005, the permittivity, waves and altimetry (PWA) subsystem, a component of the Huygens atmospheric structure instrument (HASI), detected an ionized layer at altitudes around 63 km with two different instruments, the relaxation probe (RP) and the mutual imped…
A quantitative link between globular clusters and the stellar haloes in elliptical galaxies
Forte, Juan C.; Faifer, Favio; Geisler, Doug
This paper explores the quantitative connection between globular clusters and the 'diffuse' stellar population of the galaxies they are associated with. Both NGC 1399 and NGC 4486 (M87) are well suited for this kind of analysis due to their large globular cluster populations.