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Variable Ultraviolet Absorption in the Seyfert 1 Galaxy NGC 3516: The Case for Associated Ultraviolet and X-Ray Absorption
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +3 more
We present observations of the UV absorption lines in the Seyfert 1 galaxy NGC 3516, obtained at a resolution of λ/Δλ~40,000 with the Space Telescope Imaging Spectrograph (STIS) on 2000 October 1. The UV continuum was ~4 times lower than that observed during 1995 with the Goddard High Resolution Spectrograph (GHRS), and the X-ray flux from a conte…
The role of magnetic bald patches in surges and arch filament systems
Mandrini, C. H.; Schmieder, B.; Démoulin, P. +2 more
The short-lived active region (AR) NOAA 7968 was thoroughly observed all along its disk transit (June 3 to 10, 1996) from space and from the ground. During the early stage of its evolution, flux emerged in between the two main polarities and arch filament systems (AFS) were observed to be linked to this emergence. New bipoles and a related surge w…
HST large-field weak lensing analysis of MS 2053-04: study of the mass distribution and mass-to-light ratio of X-ray luminous clusters at 0.22<z<0.83
van Dokkum, Pieter G.; Franx, Marijn; Hoekstra, Henk +1 more
We have detected the weak lensing signal induced by the cluster of galaxies MS 2053-04 (z=0.58) from a two-colour mosaic of six Hubble Space Telescope (HST) WFPC2 images. The best-fitting singular isothermal sphere model to the observed tangential distortion yields an Einstein radius rE=6.2+/-1.8arcsec, which corresponds to a velocity d…
X-ray sources in the starburst spiral galaxy M 83. Nuclear region and discrete source population
Soria, R.; Wu, K.
Chandra has resolved the starburst nuclear region of the face-on grand-design spiral M 83. Eighty-one point sources are detected (above 3.5-sigma ) in the ACIS S3 image, and 15 of them are within the inner 16\arcsec region of the galaxy. A point source with Lx ~ 3 x 1038 erg s-1 in the 0.3-8.0 keV band is found to …
Simultaneous X-ray spectroscopy of YY Gem with Chandra and XMM-Newton
Schmitt, J. H. M. M.; Burwitz, V.; Neuhäuser, R. +7 more
We report on a detailed study of the X-ray spectrum of the nearby eclipsing spectroscopic binary YY Gem. Observations were obtained simultaneously with both large X-ray observatories, XMM-Newton and Chandra. We compare the high-resolution spectra acquired with the Reflection Grating Spectrometer onboard XMM-Newton and with the Low Energy Transmiss…
Conversion of relativistic pair energy into radiation in the jets of active galactic nuclei
Vainio, R.; Schlickeiser, R.; Pohl, M. +3 more
It is generally accepted that relativistic jet outflows power the nonthermal emission from active galactic nuclei (AGN). The composition of these jets - leptonic versus hadronic - is still under debate. We investigate the microphysical details of the conversion process of the kinetic energy in collimated relativistic pair outflows into radiation t…
Ionized iron Kalpha lines in AGN X-ray spectra
Bianchi, S.; Matt, G.
The Equivalent Widths (EW) of the He- and H-like iron lines produced in photoionized, circumnuclear matter of AGN are calculated with respect to both the reflected and the total continua. We found that the EWs with respect to the total continuum may be as large as a few tens of eV, making them observable in bright Seyfert 1s by instruments on boar…
RU Cen and SX Cen: Two strongly depleted RV Tauri stars in binary systems. The RV Tauri photometric b phenomenon and binarity
Maas, T.; Van Winckel, H.; Waelkens, C.
We present a chemical abundance analysis on the basis of high signal-to-noise and high-resolution (lambda /Delta lambda ~ 48 000) optical spectra of two RV Tauri stars RU Cen and SX Cen. With an [Fe/H] = -1.9 and a [Zn/Fe] = +0.9 for RU Cen and a [Fe/H] = -1.1 and a [Zn/Fe] = +0.6 for SX Cen, both stars of spectroscopic class B display strong depl…
Saturn's F Ring: Kinematics and Particle Sizes from Stellar Occultation Studies
Nicholson, P. D.; Bosh, A. S.; Olkin, C. B. +1 more
The occultation of GSC5249-01240 by Saturn's rings was observed in a spectrally resolved mode using the Faint Object Spectrograph on the Hubble Space Telescope. By combining these data with other occultation data, we have determined the inclination of the F ring to be 0.0065±0.0014 deg. Our inclined F ring orbit model explains an abrupt decrease i…
The Infrared Space Observatory Deep Asteroid Search
Tedesco, Edward F.; Desert, François-Xavier
A total of six deep exposures (using the astronomical observation template CAM01 with a 6" pixel field of view) through the ISOCAM LW10 filter (IRAS band 1, i.e., 12 µm) were obtained on a ~15' square field centered on the ecliptic plane. Point sources were extracted using the technique described in 1999 by Désert et al. Two known asteroids …