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Mass and Angular Momentum Transfer in the Massive Algol Binary RY Persei
Gies, D. R.; Peters, G. J.; Huang, W. +12 more
We present an investigation of the Hα emission-line variations observed in the massive Algol binary RY Per. We give new radial velocity data for the secondary based on our optical spectra and for the primary based on high-dispersion UV spectra. We present revised orbital elements and an estimate of the primary's projected rotational velocity (whic…
Temperature dependence of the Lyman α line wings in cool hydrogen-rich white dwarf atmospheres. Application to ZZ Ceti white dwarf spectra
Kielkopf, J. F.; Allard, N. F.; Loeillet, B.
Theoretical Lyman α absorption profiles show a significant dependence on temperature of the H2 satellite at 1600 Å, whereas the H2+ satellite at 1400 Å remains unchanged. The use of opacities calculated with different approximations concerning the electric dipole transition moment (constant, dependent on interatomi…
RX J1821.6+6827: A cool cluster at z = 0.81 from the ROSAT NEP survey
Böhringer, H.; Wolter, A.; Briel, U. G. +3 more
We present an analysis of the properties of the cluster of galaxies RX J1821.6+6827, or NEP 5281, at a redshift z= 0.816 ±0.001. RX J1821.6+6827 was discovered during the optical identification of the X-ray sources in the North Ecliptic Pole (NEP) region of the ROSAT All-Sky Survey and it is the highest redshift cluster of galaxies of the NEP surv…
Misleading results from low-resolution spectroscopy: From galaxy interstellar medium chemistry to cosmic star formation density
Flores, H.; Hammer, F.; Gruel, N. +2 more
Low resolution spectroscopy (R=150) from the Canada-France-Redshift Survey (CFRS) revealed intriguing properties for low redshift galaxies (z ≤0.3): nearly half of their spectra show prominent Hα emission lines, but no Hβ emission line and barely detected [O II] λ3727, and [O III] λ5007 lines. We call these objects ``CFRS Hα-single" galaxies and h…
Separating spatial and temporal variations in auroral electric and magnetic fields by Cluster multipoint measurements
Buchert, S.; Karlsson, T.; Marklund, G. +2 more
Available from http://www.copernicus.org/site/EGU/annales/22/7/2463.htm?FrameEngine=false;
XMM-Newton observations of the field of γ-ray burst 980425
Piro, L.; Pian, E.; Palazzi, E. +12 more
The error box of GRB980425 has been observed by XMM- Newton in March 2002, with the aim of measuring the late epoch X-ray emission of the supernova 1998bw and of clarifying its supposed association with the GRB itself. We present here the preliminary results obtained with the EPIC PN camera. Our observations confirm the association between SN 1998…
Evidence for X-ray obscuration in Type II quasar candidates from the Sloan Digital Sky Survey
Comastri, Andrea; Vignali, Cristian; Alexander, Dave M.
Recently, Zakamska et al. selected 291 high-ionization narrow-emission-line active galactic nuclei (AGN) in the redshift range 0.3-0.83 from the Sloan Digital Sky Survey (SDSS) spectroscopic data. The sample includes both type 2 Seyfert galaxies and their higher-luminosity `cousins', Type II quasar candidates. Here we present the results on the X-…
Low-latitude coronal holes during solar maximum
Cranmer, S. R.; Kohl, J. L.; Miralles, M. P.
The Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO has been used to observe large low-latitude coronal holes during solar maximum that produced fast solar wind streams. UVCS observations show that large low-latitude coronal holes at solar maximum, coronal holes of at least 10° in longitude, have plasma properties that seem to bridge the gap b…
Close Association of an Extreme-Ultraviolet Sunspot Plume with Depressions in the Sunspot Radio Emission
Brosius, Jeffrey W.; White, Stephen M.
We obtained coordinated observations of the large sunspot in NOAA Region 8539 on 1999 May 9 and 13 with the Very Large Array and three instruments (CDS, EIT, MDI) aboard the Solar and Heliospheric Observatory satellite. The EUV observations reveal a plume in the sunspot umbra on both observing dates. The plume appears brightest in emission lines f…
X-ray variability of the Narrow Line Seyfert 1 Galaxy PKS 0558-504
Arévalo, P.; Brinkmann, W.; Gliozzi, M. +1 more
We present results from several XMM-Newton observations of the radio-loud Narrow-line Seyfert 1 galaxy (NLS1) PKS 0558-504. We find evidence for strong and persistent X-ray variability, both on short and long time-scales. On short time scales of ⪆2 hours the source varies smoothly by 15-20%; long-term variations by a factor ⪆2 could not be resolve…