Search Publications
Coronal diffusion and high solar latitude recurrent energetic particle increases.
Keppler, E.; Fraenz, M.; Quenby, J. J. +2 more
Ulysses observations have demonstrated that energetic particle flux increases are not only found to be associated with the regularly appearing recurrent fast streams seen at mid solar latitudes but also that they persist with the same periodicity of occurrence to at least 64° latitude, well into the region where no accompanying plasma speed enhanc…
PG 0009+036: a rapidly rotating normal B star in the galactic halo.
de Boer, K. S.; Heber, U.; Moehler, S. +1 more
We present the spectroscopic analysis of a rapidly rotating main sequence B star at high galactic latitude. From optical and ultraviolet spectra of PG 0009+036 we find for the atmospherical parameters T_eff_=14500K, logg=3.9, and a rotational velocity of vsini=320km/s. The effects of rotation on the fundamental parameters of the star are discussed…
Far-Ultraviolet Imaging of the Globular Cluster NGC 7099 with the Second Wide-Field and Planetary Camera
Casertano, Stefano; Ballester, Gilda E.; Crisp, David +13 more
We have imaged the globular cluster NGC 7099 in the far-UV and visible with WFPC2 on the Hubble Space Telescope. Our far-UV images show a sparsely populated and fully resolved central region. The far-UV to visible color-magnitude diagram of these stars shows a well-defined horizontal branch with no evidence for hot, more evolved descendants. We fi…
Search for neutron star spin periods in X-ray bursts.
van der Klis, M.; Jongert, H. C.
We report a search for pulsations in 147 Type 1 X-ray bursts observed with EXOSAT in 10 X-ray burst sources. Instead of treating each burst separately, we incoherently averaged the power spectra of all of the bursts of a given burster to improve statistics. No periodicities were detected; 99% confidence upper limits on the modulation depths of pos…
Energetic ion and electron observations at Jupiter's dayside magnetopause: implications for magnetopause location and boundary coupling processes
Balogh, A.; Forsyth, R. J.; Cowley, S. W. H. +7 more
An analysis is presented of the fluxes and anisotropies of energetic (MeV) ions and electrons measured by instruments of the COSPIN package during the first inbound traversal of the Jovian dayside magnetospheric boundary region by the Ulysses spacecraft in February 1992. The aim of the study is to elucidate the nature of the multiple structures ob…
X-Ray Properties of Symbiotic Stars: I. The Supersoft Symbiotic Novae RR Tel and SMC3 (=RX J0048.4-7332)
Wolff, B.; Jordan, S.; Mürset, U.
We searched the ROSAT archive for pointed PSPC observations covering positions of symbiotic stars. 16 systems are detected. We find three distinct types of energy distributions, one of which is supersoft. This class consists of seven objects, among them two symbiotic novae, RR Tel and SMC3, which are discussed in more detail in this paper. The sup…
HR 4289 - an X-ray luminous galaxy close to the bright star.
Schmitt, J. H. M. M.; Reimers, D.; Huensch, M.
Using new optical, UV and X-ray observations we show that the K5 III star HR 4289, formerly believed to be the only ROSAT All-Sky survey detection to the right of the coronal diving line, should not be identified with the X-ray source. Pointed ROSAT PSPC observations demonstrate that the X-ray source is slightly extended, and locate the X-ray sour…
Kinetic temperature ratios of O6+ and He2+: Observations from Wind/MASS and Ulysses/SWICS
Cohen, C. M. S.; Gloeckler, G.; Wilken, B. +4 more
We present results from a two spacecraft study of the ratio of O6+ and He2+ kinetic temperatures as a function of solar wind speed. Data from the Wind/MASS and Ulysses/SWICS instruments both indicate the O6+/He2+ kinetic temperature ratio increases with increasing solar wind speed, peaking near 500 km/s.…
The apsidal motion in extragalactic stars: the masses of the eclipsing binary HV 2274 in the Large Magellanic Cloud.
Claret, A.
Theoretical apsidal motion rates based on evolutionary stellar models are used to evaluate masses and radii of an extragalactic eclipsing binary (HV 2274) in the Large Magellanic Cloud. As radial velocity curves are not available, from the results of the analysis of the light curve and the detected apsidal motion it was possible to constrain the v…
UV Observations of Three LMC Be-Star/X-ray Binaries
Hauschildt, P. H.; Cowley, A. P.; Schmidtke, P. C. +4 more
This paper describes IUE ultraviolet observations of three Be-star/X-ray binaries in the LMC: CAL 9, CAL E, and RX J0520.5-6932. Because the optical spectra show evidence of an overlying continuum source, ultraviolet spectra were obtained to further investigate its properties, but no UV emission lines are found. The UV spectra have been compared t…