Search Publications
Stellar Wind Variations during the X-Ray High and Low States of Cygnus X-1
Crenshaw, D. M.; Kaper, L.; Herrero, A. +10 more
We present results from Hubble Space Telescope ultraviolet spectroscopy of the massive X-ray and black hole binary system, HD 226868 = Cyg X-1. The spectra were obtained at both orbital conjunction phases in 2002 and 2003, when the system was in the X-ray high/soft state. The UV stellar wind lines suffer large reductions in absorption strength whe…
Coupled ion and neutral rotating model of Titan's upper atmosphere
Waite, J. H.; Cravens, T. E.; Robertson, I. P. +2 more
A one-dimensional composition model of Titan's upper atmosphere is constructed, coupling 36 neutral species and 47 ions. Energy inputs from the Sun and from Saturn's magnetosphere and updated temperature and eddy coefficient parameters are taken into account. A rotating technique at constant latitude and varying local-time is proposed to account f…
Atmospheric structure and dynamics as the cause of ultraviolet markings in the clouds of Venus
Drossart, Pierre; Piccioni, Giuseppe; Markiewicz, Wojciech J. +4 more
When seen in ultraviolet light, Venus has contrast features that arise from the non-uniform distribution of unknown absorbers within the sulphuric acid clouds and seem to trace dynamical activity in the middle atmosphere. It has long been unclear whether the global pattern arises from differences in cloud top altitude (which was earlier estimated …
Complex Organic Materials in the Circumstellar Disk of HR 4796A
Weinberger, Alycia J.; Debes, John H.; Schneider, Glenn
We combine HST NICMOS imaging photometry of the HR 4796A disk at previously unobserved wavelengths between 1.71-2.22 µm with reprocessed archival observations to produce a measure of the dust's scattering efficiency as a function of wavelength. The spectrum of the dust, synthesized from the seven photometric measures, is characterized by a s…
The High-Velocity Gas toward Messier 5: Tracing Feedback Flows in the Inner Galaxy
Brown, Thomas M.; Lehner, Nicolas; Howk, J. Christopher +2 more
We present FUSE and STIS E140M observations of the post-AGB star ZNG 1 in the globular cluster Messier 5 (l = 3.9°, b = + 47.7° d = 7.5 kpc , z = + 5.3 kpc ). High-velocity absorption is seen in C IV, Si IV, O VI, and lower ionization species at LSR velocities of roughly -140 and -110 km s-1. We conclude that this gas is not circumstell…
Determining the LIC H density from the solar wind slowdown
Liu, Y.; McComas, D. J.; Wang, C. +1 more
Context: The ionized solar wind interacts directly with the interstellar neutrals which flow into the heliosphere. These neutrals are ionized, mainly by charge exchange, then accelerated to the solar wind speed with the momentum and energy removed from the bulk flow of the solar wind. Thus, by measuring the solar wind slowdown, one can estimate th…
Observations of chorus at Saturn using the Cassini Radio and Plasma Wave Science instrument
Gurnett, D. A.; Dougherty, M. K.; Hospodarsky, G. B. +4 more
Observations at Saturn of whistler mode chorus emissions have been obtained by the Cassini Radio and Plasma Wave Science instrument. Data from the first 45 orbits are analyzed, and the characteristics of the chorus emissions are discussed. Wave normal and Poynting vector measurements from the five-channel waveform receiver are used to examine the …
Point spread functions for the Solar optical telescope onboard Hinode
Wedemeyer-Böhm, S.
Aims: We investigate the combined point spread function (PSF) of the Broadband Filter Imager (BFI) and the Solar Optical Telescope (SOT) onboard the Hinode spacecraft.
Methods: Observations of the Mercury transit from November 2006 and the solar eclipse(s) from 2007 are used to determine the PSFs of SOT for the blue, green, and red continuum c…
The Population of Propellers in Saturn's A Ring
Porco, Carolyn C.; Hedman, Matthew M.; Burns, Joseph A. +1 more
We present an extensive data set of ~150 localized features from Cassini images of Saturn's A ring, a third of which are demonstrated to be persistent by their appearance in multiple images, and half of which are resolved well enough to reveal a characteristic "propeller" shape. We interpret these features as the signatures of small moonlets embed…
NGC 346 in the Small Magellanic Cloud. III. Recent Star Formation and Stellar Clustering Properties in the Bright H II Region N66
Henning, Thomas; Gouliermis, Dimitrios A.; Dolphin, Andrew E. +2 more
In the third part of our photometric study of the star-forming region NGC 346/N66 and its surrounding field in the Small Magellanic Cloud (SMC), we focus on the large number of low-mass pre-main-sequence (PMS) stars revealed by the Hubble Space Telescope observations with the Advanced Camera for Surveys. We investigate the origin of the observed b…