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מאמרים קשורים
Atlas of high-resolution emission and shell lines in Be stars. Line profiles and short-term variability.
We present an atlas of high-S/N, high-resolution ({DELTA}v=6km/s) dataof Be star emission and shell profiles. We have collected profiles ofHα and of Fe II, mostly of the λ5317 transition. Theselines have been selected to provide measures for the overall emissionstrength and for the velocity field in these disks. We have collecteddata for 77 southern and equatorial programme stars, covering the period1982-1993. This is the most comprehensive overview of profile shapes inBe disks. We propose a three-dimensional scheme in which most observedprofiles can be classified. The parameters are i) inclination, ii)optical depth, and iii) the pattern of the velocity field. A search forshort-term variability (timescales between five days and a few minutes)in six stars ended with negative result. Shortest observed timescale forvariability is a few days for well-developed disks in binary systems (HR1910, HR 2142).
| An ASCA GIS spectrum of S5 0014+813 AT Z = 3.384
ASCA has detected the z = 3.384 quasar S5 0014+813 up to energies of 34keV in the quasar rest frame using the two gas imaging spectrometer(GIS) instruments. The combined X-ray spectrum has a signal-to-noiseratio of over 50 sigma and is consistent with a single power law ofenergy slope 0.63 +/- 0.03 over the 0.8-8 keV (observed) energy range.The spectrum is also well fitted with a simple thermal bremsstrahlungmodel of kT = 40 +/- 4 keV (in the quasar frame), which raises obviouspossibilities for contributions to the diffuse X-ray background. Amaximum solid angle of Omegad/2(pi) = 0.4(90% confidence) canbe placed on the strength of a Compton reflection component above theenergy of the Fe K-edge. The Fe K 6.4 keV fluorescence line has a restframe equivalent width less than 120 eV (90% confidence) at itsredshifted energy of 1.46 keV. The weakness of these featuresdifferentiates this high-luminosity, high-redshift quasar from themajority of Seyfert galaxies using its X-ray spectrum alone. The GISslope is consistent with the slope derived by the ROSAT PositionSensitive Proportional Counter (PSPC). The normalization at 1 keV in theASCA observation is, however, a factor 30%-40% higher than in the ROSATobservation, suggesting a significant increase in the 1 keV (observed)flux over the 31.5 months between the two observations (7.2 months, restframe).
| X-ray observations of flat spectrum radio sources with the HEAO-A, Einstein and EXOSAT observatories
Most of the flat spectrum radio sources for which X-ray data collectedby three different satellites are given here are from a complete sampleof the high declination 5 GHz survey. Attention is given to tabulationsof the imaging proportional counter, low energy, and medium energyobservations.
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הכנס מאמר חדש
לינקים קשורים
הכנס לינק חדש
משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | קפיאוס |
| התרוממות ימנית: | 00h16m52.52s |
| סירוב: | +81°39'49.1" |
| גודל גלוי: | 8.671 |
| מרחק: | 33.333 פארסק |
| תנועה נכונה: | -4.2 |
| תנועה נכונה: | -22.8 |
| B-T magnitude: | 9.754 |
| V-T magnitude: | 8.761 |
קטלוגים וכינוים:
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