269 research outputs found
The FUor Candidate V582 Aurigae: First Photometric and Spectroscopic Observations
One of the most attractive events in the pre-main sequence evolution is the
FU Orionis (FUor) outburst. Because only a small number of FUor stars have been
detected to date, photometric and spectral studies of every new object are of
great interest. Recently, a new FUor candidate was discovered by Anton Khruslov
- V582 Aur. To confirm the FUors nature of this object we started regular
photometric observations with the telescopes of the National Astronomical
Observatory Rozhen (Bulgaria). A high-resolution spectrum of V582 Aur was
obtained with the 1.93 m telescope in Haute-Provence Observatory (France).Comment: 5 pages, 2 figures, to appear in Bulgarian Astronomical Journa
Short-term optical variability of high-redshift QSO's
This paper presents results of a search for short-term variability in the
optical band of selected high-luminosity, high-redshift radio-quiet quasars.
Each quasar has been monitored typically for 2 - 4 hours with a time resolution
of 2 - 5 minutes and a photometric accuracy of about 0.01 - 0.02 mag. Due to
the significant redshift (z>2), the covered wavelength range falls into the UV
region (typically 1500 - 2500A). We found no statistical evidence for any
continuum variations larger than 0.01 - 0.02 for any of the monitored objects.
Our results suggest that the presence of a short-term variability in
radio-quiet quasars is unlikely even in the UV region, contrary to reports by
other authors. This conclusion holds true at least for high-luminosity (large
black hole mass and accretion rate?) objects. The results are consistent with
the idea that significant short-term (less than 1 hour) variations in AGN,
where observed, should be attributed primarily to processes in a relativistic
jet.Comment: 7 pages, accepted for publication in MNRA
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