BV observations of W UMa-type binaries: CK Boo, BI CVn, and AH Vir

Demircan, Osman
Photoelectric BV observations of W UMa-type binaries CK Boo, BI CVn, and AH Vir are presented, and light curve variations and shifts of minima are discussed in the context of stellar activity and mass transfer. The O−C increments in three systems were found to be 0.08, 0.80, and 0.60 s per revolution, respectively. The new ephemeris for the future observations were also found.
Astrophysics and Space Science


Acciari, V. A.; et. al. (IOP Publishing, 2009-04-20)
The VERITAS collaboration reports the detection of very-high-energy gamma-ray emission from the high-frequency-peaked BL Lac object 1ES 1218+304 located at a redshift of z = 0.182. A gamma-ray signal was detected with a statistical significance of 10.4 standard deviations (10.4 sigma) for the observations taken during the first three months of 2007, confirming the discovery of this object made by the MAGIC collaboration. The photon spectrum between similar to 160 GeV and similar to 1.8 TeV is well described...
The momentum 4-vector imparted by gravitational waves in Bianchi-type metrics
Havare, A; Korunur, M; Salti, M (Springer Science and Business Media LLC, 2006-01-01)
Considering the MOller, Weinberg and Qadir-Sharif's definitions in general relativity, we find the momentum 4-vector of the closed universe based on the Bianchi-type metrics. The momentum 4-vector (due to matter plus fields) is found to be zero. This result supports the viewpoints of Albrow and Tryon and extends the previous works by Cooperstock-Israelit, Rosen, Johri et al., Banerjee-Sen and Vargas who investigated the problem of the energy in Friedmann-Robertson-Walker universe and SaltI-Havare who studie...
VERITAS discovery of > 200 GeV gamma-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae
Acciari, V. A.; et. al. (IOP Publishing, 2008-09-10)
We report the detection of very high energy gamma- ray emission from the intermediate- frequency- peaked BL Lacertae object W Comae (z = 0.102) by VERITAS. The source was observed between 2008 January and April. A strong outburst of gamma-ray emission was measured in the middle of March, lasting for only 4 days. The energy spectrum measured during the two highest flare nights is fit by a power law and is found to be very steep, with a differential photon spectral index of Gamma = 3.81 +/- 0.35(stat) +/- 0.3...
Gravitational energy-momentum density in Bianchi type II space-times
Aydogdu, Oktay (World Scientific Pub Co Pte Lt, 2006-04-01)
In this paper, using Einstein, Landau and Lifshitz's energy-momentum complexes both in general relativity and teleparallel gravity, we calculate the total energy distribution (due to matter and fields, including gravitation) associated with locally rotationally symmetric (LRS) Bianchi type II cosmological models. We show that energy densities in these different gravitation theories are the same, so they agree with each other. We obtain the result that the total energy is zero. This result agrees with previo...
Energy-momentum of a stationary beam of light in teleparallel gravity
Aydogdu, Oktay; Salti, Mustafa (Springer Science and Business Media LLC, 2006-01-01)
In this paper, we utilize the teleparallel gravity analogs of the energy and momentum definitions of Bergmann-Thomson and Landau-Lifshitz in order to explicitly evaluate the energy distribution (due to matter and fields including gravity) based on the Bormor space-time, it is shown that for a stationary beam of light, these energy-momentum definitions give the same result. Furthermore, this result supports the viewpoint of Cooperstock and also agree with the previous works by Bringley and Gad.
Citation Formats
O. Demircan, “BV observations of W UMa-type binaries: CK Boo, BI CVn, and AH Vir,” Astrophysics and Space Science, pp. 169–174, 1987, Accessed: 00, 2020. [Online]. Available: