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Satellites of the Largest Kuiper Belt Objects
Brown, M. E.; Rabinowitz, D. L.; Trujillo, C. A. +12 more
We have searched the four brightest objects in the Kuiper Belt for the presence of satellites using the newly commissioned Keck Observatory Laser Guide Star Adaptive Optics system. Satellites are seen around three of the four objects: Pluto (whose satellite Charon is well-known and whose recently discovered smaller satellites are too faint to be d…
The interplay between star formation and the nuclear environment of our Galaxy: deep X-ray observations of the Galactic centre Arches and Quintuplet clusters
Wang, Q. Daniel; Dong, Hui; Lang, Cornelia
The Galactic centre (GC) provides a unique laboratory for a detailed examination of the interplay between massive star formation and the nuclear environment of our Galaxy. Here, we present a 100-ks Chandra Advanced CCD Imaging Spectrometer (ACIS) observation of the Arches and Quintuplet star clusters. We also report on a complementary mapping of t…
Newly discovered active binaries in the RasTyc sample of stellar X-ray sources. I. Orbital and physical parameters of six new binaries
Freire Ferrero, R.; Guillout, P.; Frasca, A. +3 more
We present the first results from follow-up optical observations, both photometric and spectroscopic, of stellar X-ray sources, selected from the RasTyc sample, resulting from the cross-correlation of ROSAT All-Sky Survey (RASS) and TYCHO catalogues. In particular, we report on the discovery of six late-type binaries, for which we obtained good ra…
Jupiter's atmospheric temperatures: From Voyager IRIS to Cassini CIRS
Achterberg, Richard K.; Flasar, F. Michael; Simon-Miller, Amy A. +4 more
Retrievals performed on Cassini Composite Infrared Spectrometer data obtained during the distant Jupiter flyby in 2000/2001 have been used to generate global temperature maps of the planet in the troposphere and stratosphere, but to higher latitudes than were shown previously by Flasar et al. [Flasar, F.M., 39 colleagues, 2004a. Nature 427, 132-13…
The X-Ray Synchrotron Emission of RCW 86 and the Implications for Its Age
Vink, Jacco; Bamba, Aya; Yamazaki, Ryo +3 more
We report X-ray imaging spectroscopy observations of the northeastern shell of the supernova remnant RCW 86 using Chandra and XMM-Newton. Along this part of the shell, the dominant X-ray radiation mechanism changes from thermal to synchrotron emission. We argue that both the presence of X-ray synchrotron radiation and the width of the synchrotron-…
The ACS Virgo Cluster Survey. XIV. Analysis of Color-Magnitude Relations in Globular Cluster Systems
Jordán, Andrés; Mieske, Steffen; Tonry, John L. +8 more
We examine the correlation between globular cluster (GC) color and magnitude using HST ACS imaging for a sample of 79 early-type galaxies (-21.7<MB<-15.2 mag) with accurate SBF distances from the ACS Virgo Cluster Survey. Using the KMM mixture modeling algorithm, we find a highly significant correlation, γz≡d(g-z)/dz=-0…
A regular period for Saturn's magnetic field that may track its internal rotation
Russell, C. T.; Dougherty, M. K.; Smith, E. J. +1 more
The rotation rate of a planet is one of its fundamental properties. Saturn's rotation, however, is difficult to determine because there is no solid surface from which to time it, and the alternative `clock'-the magnetic field-is nearly symmetrically aligned with the rotation axis. Radio emissions, thought to provide a proxy measure of the rotation…
XMM-Newton and Chandra measurements of the AGN intrinsic absorption: dependence on luminosity and redshift
Georgakakis, A.; Hatziminaoglou, E.; Georgantopoulos, I. +2 more
We combine bright XMM-Newton data with the Chandra Deep Field South observations to explore the behavior of the intrinsic AGN absorption, as a function of redshift and luminosity. Our sample consists of 359 sources selected in the hard 2-8 keV band, spanning the flux range 6 × 10-16-3 × 10-13 erg~cm-2~s-1
Constraints on dark matter and the shape of the Milky Way dark halo from the 511-keV line
Knödlseder, J.; Jean, P.; Ascasibar, Y. +1 more
About one year ago, it was speculated that decaying or annihilating light dark matter (LDM) particles could explain the flux and extension of the 511-keV line emission in the Galactic Centre. Here, we present a thorough comparison between theoretical expectations of the Galactic positron distribution within the LDM scenario and observational data …
Carbon dioxide photoelectron energy peaks at Mars
Coates, A. J.; Kallio, E.; Fedorov, A. +40 more
The ELectron Spectrometer (ELS) from the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) flown on the Mars Express spacecraft has an 8% energy resolution, combined with the capability to oversample the martian electron distribution. This makes possible the resolution and identification of electrons generated as a result of the He 304 Å io…