Search Publications
Loss of the Surface Layers of Comet Nuclei
Keller, H. U.; Thomas, N.; Alexander, C.
The Deep Impact observations of low thermal inertia for comet 9P/Tempel 1 are of profound importance for the observations to be made by the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. While sub-surface sublimation is necessary to explain the observations, the depth at which this occurs is no more than 2 3 cm and possibly less. The low t…
In Search of the Largest Velocity Dispersion Galaxies
Shields, G. A.; Gebhardt, K.; Bernardi, M. +2 more
We present Hobby-Eberly Telescope (HET) observations for galaxies at redshift z < 0.3 from the Sloan Digital Sky Survey (SDSS) showing large velocity dispersions while appearing to be single galaxies in HST images. The high signal-to-noise HET spectra provide more definitive velocity dispersions. The maximum velocity dispersion we find is σ
No Evidence of Morning or Large-Scale Drizzle on Titan
Geballe, Thomas R.; Kim, Sang J.; Trafton, Laurence M.
Widespread methane precipitation on Titan has been predicted by several authors since methane saturation in the upper troposphere was measured by the Huygens probe over its landing site. Recently, observational evidence of widespread morning drizzle has been suggested based on detection of a dark morning site in surface-subtracted 2 µm spect…
Asiago eclipsing binaries program. III. V570 Persei
Munari, U.; Zwitter, T.; Sordo, R. +4 more
The orbit and physical parameters of the previously unsolved double-lined eclipsing binary V570 Per, discovered by the Hipparcos satellite, were derived using high-resolution Echelle spectroscopy and B, V photoelectric photometry. The metallicity from χ2 analysis of the spectra is [ M/H]=+0.02±0.03, and reddening from interstellar NaI a…
Complexities of a 3-D plasmoid flux rope as shown by an MHD simulation
Baker, D. N.; Wiltberger, M.; Farr, N. L.
The results of a global magnetohydrodynamic (MHD) simulation of a pair of magnetospheric substorms on 11 August 2002 are presented. Comparisons of data with simulation results reveal a good agreement regarding the sequence of events during substorm development. We give particular emphasis to results in the simulation of a flux rope formed during t…
Line intensity enhancements in stellar coronal X-ray spectra due to opacity effects
Mathioudakis, M.; Keenan, F. P.; Matranga, M. +2 more
Context: The I(15.01 Å)/I(16.78 Å) emission line intensity ratio in Fe xvii has been reported to deviate from its theoretical value in solar and stellar X-ray spectra. This is attributed to opacity in the 15.01 Å line, leading to a reduction in its intensity, and was interpreted in terms of a geometry in which the emitters and absorbers are spatia…
An Analysis of the Dust Halo and Extinction toward X Persei
Smith, Randall K.; Valencic, Lynne A.
Interstellar dust grain models are not sufficiently constrained by UV extinction curves to allow researchers to distinguish between them. By testing grain models in the X-ray regime and applying elemental abundance constraints, we show to what extent the models can reproduce the observables in these regimes and whether they are capable of doing so…
Phase-dependent X-ray observations of the β Lyrae system. No eclipse in the soft band
Hamann, W. -R.; Oskinova, L. M.; Ignace, R. +2 more
Aims:We report on observations of the eclipsing and interacting binary β Lyrae from the Suzaku X-ray telescope. This system involves an early B star embedded in an optically and geometrically thick disk that is siphoning atmospheric gases from a less massive late B II companion.
Methods: Motivated by an unpublished X-ray spectrum from the Eins…
Discovery of X-ray pulsations from the HMXB source AXJ1749.1-2733
Tsygankov, S. S.; Lutovinov, A. A.; Karasev, D. I.
We are reporting the discovery of X-ray pulsations from the source AXJ1749.1-2733 with the period of ~132 s based on the XMM-Newton data obtained in 2007 March. The observed pulse profile has a double-peaked structure with the pulse fraction of about 25-30 per cent in the 3-10 keV energy band. We have also found that a periodicity with practically…
IRAS 04325+2402C: A Very Low Mass Object with an Edge-On Disk
Wood, Kenneth; Doyon, René; Lafrenière, David +3 more
IRAS 04325+2402C is a low-luminosity object located near a protostar in Taurus. We present new spatially resolved millimeter observations, near-infrared spectroscopy, and Spitzer photometry that improve the constraints on the nature of this source. The object is clearly detected in our 1.3 mm interferometry map, allowing us to estimate the mass in…