Search Publications
Emergent Spectra from Disks Surrounding Kerr Black Holes: Effect of Photon Trapping and Disk Self-shadowing
Li, Guang-Xing; Cao, Xinwu; Yuan, Ye-Fei
Based on a new estimation of their thickness, the global properties of relativistic slim accretion disks are investigated in this work. The resulting emergent spectra are calculated using the relativistic ray-tracing method, in which we neglect the self-irradiation of the accretion disk. The angular dependence of the disk luminosity, the effects o…
Chandra Observation of Polaris: Census of Low-mass Companions
Evans, Nancy Remage; Schlegel, Eric; Karovska, Margarita +5 more
We have observed Cepheid Polaris (α UMi A: F7 Ib [Aa] + F6 V [Ab]) with Chandra ACIS-I for 10 ks. An X-ray source was found at the location of Polaris with log LX = 28.89 erg s-1 (0.3-8 keV) and kT = 0.6 keV. A spectrum this soft could come from either the supergiant or the dwarf, as shown by comparable coronal stars. Two res…
Inverse-Compton X-rays from giant radio galaxies at z ~ 1
Fabian, A. C.; Laskar, T.; Blundell, K. M. +1 more
We report XMM-Newton observations of three FR II radio galaxies at redshifts between 0.85 and 1.34, which show extended diffuse X-ray emission within the radio lobes, likely due to inverse-Compton up-scattering of the cosmic microwave background. Under this assumption, through spectrum fitting together with archival Very Large Array radio observat…
A study of the interacting binary V393Scorpii
Mennickent, R. E.; Kołaczkowski, Z.; Graczyk, D. +1 more
We present high-resolution J-band spectroscopy of V393Sco obtained with the Cryogenic High-Resolution Infrared Echelle Spectrograph (CRIRES) at the ESO Paranal Observatory along with a discussion of archival International Ultraviolet Explorer (IUE) spectra and published broad-band magnitudes. The best fit to the spectral energy distribution outsid…
Shaping the Glowing Eye Planetary Nebula, NGC 6751
López, J. A.; García-Díaz, Ma. T.; Richer, M. G. +2 more
NGC 6751 is a highly structured multiple-shell planetary nebula (PN) with a bipolar outflow. In this work, we present a comprehensive set of spatially resolved, high spectral resolution, long-slit spectra and deep imaging from San Pedro Mártir, Gemini, the Hα composite full sky survey and archive images from the Hubble Space Telescope and Spitzer.…
Atmospheric control of the cooling rate of impact melts and cryolavas on Titan’s surface
Sotin, Christophe; Baines, Kevin H.; Choukroun, Mathieu +4 more
As on Earth, Titan's atmosphere plays a major role in the cooling of heated surfaces. We have assessed the mechanisms by which Titan's atmosphere, dominantly N 2 at a surface pressure of 1.5 × 10 5 Pa, cools a warm or heated surface. These heated areas can be caused by impacts generating melt sheets and (possibly) by endogeni…
Interaction of Saturn's magnetosphere and its moons: 3. Time variation of the Enceladus plume
Russell, C. T.; Khurana, K. K.; Gombosi, T. I. +3 more
The major momentum-loading source in Saturn's magnetosphere, Enceladus, has been studied with seven Cassini flybys between 2005 and 2008. In this paper, we first use parameter tests with our 3-D magnetohydrodynamic simulation to demonstrate and determine the sensitivity of the interaction to both electron impact rates and charge-exchange rates. We…
Waves at the electron plasma frequency associated with solar wind magnetic holes: STEREO/Cluster observations
Henri, P.; Soucek, J.; Mangeney, A. +1 more
Magnetic depressions are common structures of the interplanetary medium. These magnetic holes can be just isolated dips of the amplitude of the field or they can be associated with discontinuities in the field orientation (tangential or rotational). Electrostatic waves at the plasma frequency (Langmuir waves) are often observed in these magnetic s…
Search for Steins’ surface inhomogeneities from OSIRIS Rosetta images
Jorda, L.; Sierks, H.; Barbieri, C. +10 more
We investigate the possible presence of heterogeneous surface features on asteroid (2867) Steins, using the G-mode multivariate statistical method ( Coradini et al., 1977) applied to Rosetta/OSIRIS images. We analyze both NAC and WAC images obtained near around the closest approach that occurred on September 5th, 2008, through different filters ce…
SMEI 3D Reconstruction of a Coronal Mass Ejection Interacting with a Corotating Solar Wind Density Enhancement: The 2008 April 26 CME
Webb, D. F.; Jackson, B. V.; Buffington, A. +3 more
The Solar Mass Ejection Imager (SMEI) has recorded the brightness responses of hundreds of interplanetary coronal mass ejections (CMEs) in the interplanetary medium. Using a three-dimensional (3D) reconstruction technique that derives its perspective views from outward-flowing solar wind, analysis of SMEI data has revealed the shapes, extents, and…