Search Publications
T Tauri Jet Physics Resolved Near the Launching Region with the Hubble Space Telescope
Bacciotti, Francesca; Coffey, Deirdre; Podio, Linda
We present an analysis of the gas physics at the base of jets from five T Tauri stars based on high angular resolution optical spectra, using the Hubble Space Telescope Imaging Spectrograph (HST STIS). The spectra refer to a region within 100 AU of the star, i.e., where the collimation of the jet has just taken place. We form position-velocity (PV…
Initial Measurements of Black Hole Spin in GX 339-4 from Suzaku Spectroscopy
Fabian, A. C.; Miller, J. M.; Reynolds, C. S. +6 more
We report on a deep Suzaku observation of the stellar-mass black hole GX 339-4 in outburst. A clear, strong, relativistically shaped iron emission line from the inner accretion disk is observed. The broadband disk reflection spectrum revealed is one of the most sensitive yet obtained from an accreting black hole. We fit the Suzaku spectra with a p…
Tidally driven stress accumulation and shear failure of Enceladus's tiger stripes
Pappalardo, Robert T.; Smith-Konter, Bridget
Straddling the south polar region of Saturn's moon Enceladus, the four principal "tiger stripe" fractures are a likely source of tectonic activity and plume generation. Here we investigate tidally driven stress conditions at the tiger stripe fractures through a combined analysis of shear and normal diurnal tidal stresses and accounting for additio…
Two-spacecraft reconstruction of a magnetic cloud and comparison to its solar source
Möstl, C.; Farrugia, C. J.; Temmer, M. +5 more
This paper compares properties of the source region with those inferred from satellite observations near Earth of the magnetic cloud which reached 1 AU on 20 November 2003. We use observations from space missions SOHO and TRACE together with ground-based data to study the magnetic structure of the active region NOAA 10501 containing a highly curve…
High precision X-ray log N - log S distributions: implications for the obscured AGN population
Treister, E.; Ebrero, J.; Page, M. J. +13 more
Context: Our knowledge of the properties of AGN, especially those of optical type-2 objects, is very incomplete. Because extragalactic source count distributions are dependent on the cosmological and statistical properties of AGN, they provide a direct method of investigating the underlying source populations.
Aims: We aim to constrain the ext…
An equatorial oscillation in Saturn's middle atmosphere
Strobel, D. F.; Flasar, F. M.; Bézard, B. +3 more
The middle atmospheres of planets are driven by a combination of radiative heating and cooling, mean meridional motions, and vertically propagating waves (which originate in the deep troposphere). It is very difficult to model these effects and, therefore, observations are essential to advancing our understanding of atmospheres. The equatorial str…
The Origin of the Intrinsic Scatter in the Relation Between Black Hole Mass and Bulge Luminosity for Nearby Active Galaxies
Ho, Luis C.; Barth, Aaron J.; Im, Myungshin +4 more
We investigate the origin of the intrinsic scatter in the correlation between black hole mass (MBH) and bulge luminosity (Lbul) in a sample of 45 massive, local (zlesssim 0.35) type 1 active galactic nuclei (AGNs). We derive MBH from published optical spectra assuming a spherical broad-line region, and Lbul
Determining Atmospheric Conditions at the Terminator of the Hot Jupiter HD 209458b
Sing, David K.; Ehrenreich, D.; Lecavelier des Etangs, A. +3 more
We present a theoretical model fit to the HST STIS optical transit transmission spectrum of HD 209458b. In our fit, we use the sodium absorption line profile along with the Rayleigh scattering by H2 to help determine the average temperature-pressure profile at the planetary terminator and infer the abundances of atomic and molecular spe…
Fluvial erosion and post-erosional processes on Titan
Sotin, Christophe; Barnes, Jason W.; Rodriguez, Sebastien +16 more
The surface of Titan has been revealed by Cassini observations in the infrared and radar wavelength ranges as well as locally by the Huygens lander instruments. Sand seas, recently discovered lakes, distinct landscapes and dendritic erosion patterns indicate dynamic surface processes. This study focus on erosional and depositional features that ca…
XMM-Newton observations of the supernova remnant IC 443. II. Evidence of stellar ejecta in the inner regions
Troja, E.; Miceli, M.; Bocchino, F. +1 more
Aims: We investigate the spatial distribution of the physical and chemical properties of the hot X-ray emitting plasma of the supernova remnant IC 443, to derive important constraints on its ionization stage, on the progenitor supernova explosion, on the age of the remnant, and its physical association with a close pulsar wind nebula.
Methods:…