Search Publications
UV Spectral Synthesis of Vega
Fitzpatrick, E. L.
We show that the UV spectrum (1280-3200 Å) of the "superficially normal" A-star Vega, as observed by the International Ultraviolet Explorer (IUE) satellite at a resolution comparable to the star's rotational broadening width, can be fit remarkably well by a single-temperature synthetic spectrum based on LTE atmosphere models and a newly constructe…
HD 181906: A star with two systems of active longitudes on its surface
Savanov, I. S.
We use continuous 156-day COROT photometric observations of the F dwarf HD 181906 to analyze temperature inhomogeneities on the stellar surface and follow their evolution. The analysis used the iPH code, which solves for the temperature inhomogeneities in a two-temperature approximation without any assumptions about the shape or number of spots on…
Hubble Space Telescope observations of Europa in and out of eclipse
Ford, H. C.; Sparks, W. B.; Hough, J. H. +7 more
Europa is a prime target for astrobiology and has been prioritized as the next target for a National Aeronautics and Space Administration flagship mission. It is important, therefore, that we advance our understanding of Europa, its ocean and physical environment as much as possible. Here, we describe observations of Europa obtained during its orb…
Plasma conditions and the structure of the Jovian ring
Horányi, Mihály; Juhász, Antal
We explore the dynamics of small charged dust particles in Jupiter's innermost magnetosphere and show that the systematic charge variation of the grains results in surprisingly short lifetimes. Assuming a constant production of small dust particles via continual micrometeoroid bombardment of the larger parent bodies of the main ring, this model re…
The evolution of planetary nebulae. VI. On the chemical composition of the metal-poor PN G135.9+55.9
Steffen, M.; Roth, M. M.; Schönberner, D. +2 more
The actual value of the oxygen abundance of the metal-poor planetary nebula
INTEGRAL probes the morphology of the Crab nebula in hard X-rays/soft γ-rays
Eckert, D.; Ferrigno, C.; Savchenko, V. +1 more
Aims: We use the IBIS/ISGRI telescope on-board INTEGRAL to measure the position of the centroid of the 20-200 keV emission from the Crab region.
Methods: We find that the astrometry of the IBIS telescope is affected by the temperature of the IBIS mask during the observation. After correcting for this effect, we show that the systematic e…
A new approach for deriving the solar irradiance from nonflaring solar upper atmosphere plasmas at 2 × 104 ≤ T ≤ 2 × 107 K
Fontes, C. J.; Landi, E.; Doschek, G. A. +7 more
We propose a new approach for deriving the solar irradiance due to the emission by solar upper atmosphere plasmas at 2 × 104 ≤ T ≤ 2 × 107 K for wavelengths shorter than 800 Å. Our approach is based on a new understanding of the properties of the solar upper atmosphere; specifically, the discovery that the majority of emissio…
Seasonal Change on Titan
Flasar, F. Michael; Lorenz, Ralph D.; Brown, Michael E.
Titan displays seasonal changes in the distribution of gas and hazes in its atmosphere, in the character of its methane clouds, and in its temperatures and winds. While Cassini has observed some of these changes in detail, some are observable from Earth, and the period of most rapid change may be just about to begin in the years after equinox.
Timing of changes in the solar wind energy input in relation to ionospheric response
Janhunen, P.; McComas, D. J.; Palmroth, M. +3 more
We investigate four consecutive substorms using observations and global MHD simulation code GUMICS-4. The solar wind energy input is estimated by the epsilon parameter and evaluated from the simulation by direct integration of the energy transfer through the magnetopause. The ionospheric dissipation is estimated using the AE index and also evaluat…
Variable O VI and N V Emission from the X-ray Binary LMC X-3: Heating of the Black Hole Companion
Tripp, Todd M.; Steiner, James F.; McClintock, Jeffrey E. +8 more
Based on high-resolution ultraviolet spectroscopy obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Cosmic Origins Spectrograph, we present new detections of O VI and N V emission from the black hole X-ray binary (XRB) system LMC X-3. We also update the ephemeris of the XRB using recent radial velocity measurements obtained w…