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Hubble Space Telescope Astrometric Observations and Orbital Mean Motion Corrections for the Inner Satellites of Neptune
Pascu, Dan; Rohde, James R.; Seidelmann, P. Kenneth +6 more
Six small inner satellites of Neptune were imaged in 1989 with Voyager 2. In 1997, we recovered the four outermost with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 for astrometric, dynamical, and photometric studies. The ring arcs were not detected in our images. Thirteen exposures were taken in each of three HST orbits: two orb…
Discovery of a Peculiar Pulsar in the Small Magellanic Cloud
Ueno, Masaru; Yamaguchi, Hiroya; Takagi, Shin-Ichiro +2 more
We report on a peculiar X-ray binary pulsar, IKT 1 = RX J0047.3 - 7312, observed with XMM-Newton in 2000 October. The X-ray spectrum is described by a two-component spectrum. The hard component has a broken power-law with respective photon indices of 0.2 and 1.8, below and above the break energy at 5.8keV. The soft component can be modeled by a bl…
An XMM-Newton and Chandra View of Massive Clusters of Galaxies to z = 1
Gondoin, P.; Maughan, B. J.; Mason, K. O. +7 more
The X-ray properties of a sample of high redshift (z>0.6), massive clusters observed with XMM-Newton and Chandra are described, including two exceptional systems. One, at z = 0.89, has an X-ray temperature of T = 11.5+1.1-0.9 keV (the highest temperature of any cluster known at z>0.6), an estimated mass of ≅(1.4±0.2)x10…
Laboratory experiments on cometary materials
Brucato, J. R.; Colangeli, L.; Bar-Nun, A. +2 more
Laboratory experiments to simulate cometary materials and their processing contribute to the investigation of the properties and evolution of comets. Experimental methods can produce both refractory materials and frozen volatiles with chemical, structural, and morphological characteristics that reproduce those of materials observed and/or expected…
Dispersive Alfvén Waves Observed by Cluster at the Magnetopause
Khotyaintsev, Y.; Stasiewicz, K.; Grzesiak, M.
We have analyzed ELF turbulence ∼0.03 - 10 Hz) observed by Cluster at the magnetopause layer during 120 multiple magnetopause crossings on a single event, December 31, 2000, 09-16 UT. Multiple crossings are produced by nonlinear, large amplitude surface waves at the magnetopause. Waves below the proton gyrofrequency fci ≈ 0.3 Hz) are identified as…
Imaging principles and techniques in space-borne gamma-ray astronomy
Schönfelder, Volker
Gamma-ray astronomy in the photon energy band from several 100keV up to say 10GeV can only be performed from space. Tremendous progress has been made in this young research field during the last 40 years. All-Sky maps exist now in continuum and line emission and short gamma-ray bursts-lasting only seconds-can be located to better than 1arcmin. The…
Total Solar Irradiance Variation During Rapid Sunspot Growth
Fröhlich, Claus; Zahid, H. Jabran; Hudson, Hugh S.
Large sunspot areas correspond to dips in the total solar irradiance (TSI), a phenomenon associated with the local suppression of convective energy transport in the spot region. This results in a strong correlation between sunspot area and TSI. During the growth phase of a sunspot other physics may affect this correlation; if the physical growth o…
An Optical and X-Ray Examination of Two Radio Supernova Remnant Candidates in 30 Doradus
Chu, You-Hua; Gruendl, Robert A.; Chen, C. -H. Rosie +2 more
The giant H II region 30 Doradus is known for its violent internal motions and bright diffuse X-ray emission, suggesting the existence of supernova remnants (SNRs), but no nonthermal radio emission has been detected. Recently, Lazendic et al. compared the Hα/Hβ and radio/Hα ratios and suggested two small radio sources to be nonthermal and thus SNR…
Is T Leonis a superoutbursting intermediate polar?
Schmitt, J. H. M. M.; Ness, J. -U.; Vrielmann, S.
We present an XMM-Newton analysis of the cataclysmic variable T Leo. The X-ray light curve shows sinusoidal variation on a period Px equal to 0.89+0.14-0.10 times the previously spectroscopically determined orbital period. Furthermore, we find a signal in the power spectrum at 414 s that could be attributed to the …
Quantitative interpretation of the rotation curves of spiral galaxies at redshifts z ∼ 0.7 and z ∼ 1
Böhm, A.; Ziegler, B. L.; Möllenhoff, C. +1 more
We present decompositions of the rotation curves of three spiral galaxies at redshifts z ∼ 0.7 and 1 into contributions by their bulges, disks, and dark halos, respectively. In order to set constraints on the degeneracy of the decompositions we interpret the morphology of the spiral structures quantitatively in the framework of density wave theory…