scholarly journals Long-term optical photometric monitoring of the quasar SDSS J153259.96−003944.1

2005 ◽  
Vol 359 (3) ◽  
pp. 1022-1028 ◽  
Author(s):  
C. S. Stalin ◽  
R. Srianand
2006 ◽  
Vol 463 (1) ◽  
pp. 243-249 ◽  
Author(s):  
P. De Cat ◽  
M. Briquet ◽  
C. Aerts ◽  
K. Goossens ◽  
S. Saesen ◽  
...  

Author(s):  
E. Semkov ◽  
S. Ibryamov ◽  
S. Peneva ◽  
A. Mutafov

A phenomenon with a significant role in stellar evolution is the FU Orionis (FUor) type of outburst. The first three (classical) FUors (FU Ori, V1515 Cyg and V1057 Cyg) are well-studied and their light curves are published in the literature. But recently, over a dozen new objects of this type were discovered, whose photometric history we do not know well. Using recent data from photometric monitoring and data from the photographic plate archives we aim to study, the long-term photometric behavior of FUor and FUor-like objects. The construction of the historical light curves of FUors could be very important for determining the beginning of the outburst, the time to reach the maximum light, the rate of increase and decrease in brightness, the pre-outburst variability of the star. So far we have published our results for the light curves of V2493 Cyg, V582 Aur, Parsamian 21 and V1647 Ori. In this paper we present new data that describe more accurate the photometric behavior of these objects. In comparing our results with light curves of the well-studied FUors (FU Ori, V1515 Cyg and V1057 Cyg), we conclude that every object shows different photometric behavior. Each known FUor has a different rate of increase and decrease in brightness and a different light curve shape.


2009 ◽  
Vol 499 (3) ◽  
pp. 967-982 ◽  
Author(s):  
J. Cuypers ◽  
C. Aerts ◽  
P. De Cat ◽  
J. De Ridder ◽  
K. Goossens ◽  
...  

1996 ◽  
Vol 173 ◽  
pp. 53-54
Author(s):  
D. Sinachopoulos ◽  
M. Burger ◽  
E. van Dessel ◽  
M. Geffert ◽  
M. Thibor ◽  
...  

We present our first results of a photometric monitoring project of the twin quasar 0957+561. This project aims mainly at the improvement of the determination of the time delay ΔT(A,B) for this gravitational lens, since the “time delay controversy on QSO 0957+561 (is) not yet decided” (Pelt et al. 1994). In addition, the quite large field of the CCD used allows also a long-term astrometric and photometric study of stars and galaxies in the field within a radius of about 10 arcminutes around the lens.


1986 ◽  
Vol 7 ◽  
pp. 211-213 ◽  
Author(s):  
E. F. Guinan ◽  
G. P. McCook ◽  
R. H. Koch ◽  
R. J. Pfeiffer

AbstractThe VV Cep close binary system (O8V + M2 lab; P = 20 3 yrs.) is described from published spectral, radial velocity, photometric, and astrometric results. A long-term photometric monitoring program shows intrinsic variability in a red bandpass. Variability exists on several time scales and the longest of these is attributed to tidal distortion of the cool supergiant by the equally massive hot companion. A theoretical “distortion” light curve, when faced against the observations, indicated the radius of the supergiant to be significantly smaller than the accepted value of ~1600R⊙. This conclusion is examined in the context of a pulse of polarized red light occurring near the time of periastron and interpreted as Roche Lobe overflow of the supergiant envelope. It is shown that the photometric and polarimetrie results may be made accordant, not by appeal to a very large level of scattered red light, but rather by invoking the loss of constraint originally imposed by the Roche Lobe geometry.


2003 ◽  
Vol 12 (4) ◽  
Author(s):  
C. Sterken

AbstractThe fundamental problem of long-term photometric monitoring of variable stars and of multi-wavelength photometric campaigns is the problem of bringing the data to a common standard. Such homogenization can be achieved only when the measurements are made in photometric systems that are truly transformable. This fundamental problem is of a technical nature, and photometric observers, sometimes, are not aware of the problems. This frequently leads to over-interpretation of the data.


2013 ◽  
Vol 9 (S302) ◽  
pp. 350-358
Author(s):  
Heidi Korhonen

AbstractThe existence of starspots on late-type giant stars in close binary systems, that exhibit rapid rotation due to tidal locking, has been known for more than five decades. Photometric monitoring spanning decades has allowed studying the long-term magnetic activity in these stars revealing complicated activity cycles. The development of observing and analysis techniques that has occurred during the past two decades has also enabled us to study the detailed starspot and magnetic field configurations on these active giants. In the recent years magnetic fields have also been detected on slowly rotating giants and supergiant stars. In this paper I review what is known of the surface magnetism in the cool giant and supergiant stars.


2015 ◽  
Vol 218 (2) ◽  
pp. 18 ◽  
Author(s):  
Ben-zhong Dai ◽  
Wei Zeng ◽  
Ze-jun Jiang ◽  
Zhong-hui Fan ◽  
Wen Hu ◽  
...  

Author(s):  
A. Arbet-Engels ◽  
D. Baack ◽  
M. Balbo ◽  
A. Biland ◽  
T. Bretz ◽  
...  

2006 ◽  
Vol 2 (S235) ◽  
pp. 78-78
Author(s):  
X. Pu ◽  
W. Bian ◽  
K. Huang

Variability phenomenon in active galactic nuclei (AGNs) provides a powerful constrain on their central engine. For a long time the long-term multi-wavelength photometric monitoring plays an important role in obtaining the optical variability of QSOs. However, it just monitors the flux variability in a few points in the wavelength which usually consists of many components including continuum and strong emission line (although the photometric data are accurate). So it is necessary to study the optical spectral variability using spectroscopic monitoring data.


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