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Extended X-Ray Emission from the Planetary Nebula BD +30°3639
Kwok, Sun; Leahy, D. A.; Yin, Donghui
We report the discovery of extended X-ray emission from the planetary nebula BD +30deg3639. Analysis of the ROSAT HRI image shows clearly that BD +30deg3639 has extended X-ray emission which is well fitted with a Gaussian source of σ=1.7"-2.8" (95.4% confidence interval). This size is consistent with being the same as that of…
The May 1997 SOHO-Ulysses quadrature
Romoli, M.; Goldstein, B. E.; Neugebauer, M. +3 more
We present results from the May 1997 SOHO-Ulysses quadrature (SOHO-Sun-Ulysses angle=90°), near sunspot minimum. Ulysses was at 5.1 AU, 10° north of the solar equator, and off the east limb. It was also at the very northern edge of the streamer belt. Nevertheless, the Solar Wind Observations Over the Poles of the Sun instrument (SWOOPS) detected o…
Evolution of White Dwarfs in Cataclysmic Variables
Gänsicke, Boris T.
Has Blending Compromised Cepheid-based Determinations of the Extragalactic Distance Scale?
Gibson, Brad K.; Sakai, Shoko; Maloney, Philip R.
We examine the suggestion that half of the galaxies observed by the Hubble Space Telescope Key Project and the Type Ia Supernova Calibration Team have had their distances systematically underestimated, by 0.1-0.3 mag in the distance modulus, because of the underappreciated influence of stellar profile blending on the Wide Field Camera chips. The s…
Chromospheric two-component NLTE modelling of the binary system V 711 Tau = HR 1099
Lanzafame, A. C.; Rodonò, M.; Busà, I.
In this paper we present the first two-component, semi-empirical chromospheric model of the RS CVn binary system V 711 Tau based on detailed fits of Hα and Mg II h line profiles. Synthetic Hα and Mg II h line profiles are computed by means of NLTE radiative transfer calculations. Using the observed Emission Measure distribution to constrain the tr…
The Orbit of the Classical Cepheid AW Persei Revisited
Evans, Nancy Remage; Wahlgren, Glenn M.; Vinko, Jozsef
We have obtained new velocity data for the classical Cepheid AW Persei and used them to derive a new orbit for the binary star system of which it is part. The orbital period (40 yr) is slightly longer than the previously determined orbit. The lower limit to the mass of the secondary from the new mass function is 6.6 Msolar. This is much…
Solar spectroradiometry with the telescope and spectrograph SUMER on the Solar and Heliospheric Observatory SOHO
Wilhelm, K.; Curdt, W.; Schühle, U. +4 more
Velocity Shear-induced Mode Conversion in Solar Wind and Streamer Plasmas
Kaghashvili, Edisher Kh.; Esser, Ruth
The possible scenario of Alfvén wave transformation into other MHD waves due to inhomogeneous flow in different regions of solar wind/corona is examined. We have chosen four examples with different plasma parameters and velocity shear parameters as representative cases for the plasma conditions. Two of the cases are representative of coronal holes…
Particle and X-ray damage in pn-CCDs
Meidinger, Norbert; Schmalhofer, Bernhard; Strüder, Lothar
The fully depleted pn-junction charge coupled device (pn-CCD) has been developed as a detector for X-ray imaging and high-resolution spectroscopy for the X-ray satellite missions XMM and ABRIXAS. If the detector is exposed to a particle radiation environment, the energy resolution is degraded due to charge transfer losses and a dark current increa…
Evolution of the Symbiotic Star AS338 after Its Strong Outburst in 1983
Munari, U.; Mikolajewska, J.; Kolotilov, E. A. +5 more
The photometric UBV observations of AS338 that we began after its outburst in 1983 are presented. They were accompanied by yearly spectroscopic observations and by occasional estimations of the star's infrared JHKL magnitudes. In June 1993, the star's optical spectrum was extended to the ultraviolet via IUE observations of AS338. Collectively, the…