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AGNS and MICROQUASARS As High-Energy γ-Ray Sources
Paredes, Josep M.
The extragalactic analogs of the microquasars, the quasars, are strong γ-ray emitters at GeV energies. It is expected that microquasars are also γ-ray sources, because of the analogy with quasars and because theoretical models predict the high-energy emission. There are two microquasars that appear as the possible counterparts for two unidentified…
Periodicity Search in the X-ray Data of RX J0007.0+7302
Lin, Lupin C. -C.; Chang, Hsiang-Kuang
Some unidentified EGRET sources have been reported to have probable X-ray counterparts. Periodicities in the X-ray data of those sources, if found, may help to strengthen the identification and to reveal their nature. We performed a detailed search of periodicities with a photon-counting method, the H-test, in the XMM and ASCA data of RX J0007.0+7…
Preliminary Analysis of <Emphasis Type="BoldItalic">V</Emphasis> and <Emphasis Type="BoldItalic">Hp</Emphasis> Light Curves of 26 Carbon Miras
MikulÁšek, Zdeněk; GrÁf, TomÁš
Light variations of a representative sample of 26 more or less periodically variable carbon stars were analyzed on the basis of 2220 individual observations made by the Hipparcos satellite and 33 544 visual observations listed in AFOEV and VSOLJ databases within the interval JD = 2 448 000 (1988) ±6 cycles. We found the osculating linear ephemerid…
An Outburst Detected in the Spectrum of Hd 6226
Šlechta, Miroslav; Škoda, Petr
HD 6226 is a bright binary Be star at visual magnitude 6.81 (Hipparcos database). The emission and absorption phases occur in cycles, which are probably not periodic. The suspected period of about 630 days (derived from photometric measurements) is not confirmed by our spectroscopic survey. The latest emission phase developed in the beginning of 2…
Multiwavelength Study of two Unidentified γ-ray Sources
Caraveo, Patrizia; La Palombara, Nicola; Bignami, Giovanni F. +3 more
Most counterparts of the identified low-latitude γ-ray sources are isolated neutron stars (INSs). Since INSs are characterized by an extremely high value of f X/f opt, a systematic X-ray/optical coverage of the fields of unidentified low-latitude γ-ray sources is the best way to unveil INS counterparts of unidentified sources…
Towards an Understanding of Radial Velocity Shift in Uv Spectra of Symbiotic Stars
Friedjung, Michael; Mikołajewska, Joanna
A systematic redshift of high ionization resonance emission lines relative to the intercombination lines was found by Friedjung et al. (1883, A & A126, 4071983) in the UV spectra of a number of symbiotic binaries. The interpretation was not then clear. We present a study of archival IUE and GHRS/HST spectra of the symbiotic binary CI Cyg. The …