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Physical parameters of the semiregular variable red giant 2 Cen
Arkharov, A. A.; Ruban, E. V.; Hagen-Thorn, E. I. +1 more
This is a study of photometric data from the Hipparcos catalog and spectrophotometric observations by a group of Pulkovo observers in Bolivia of the variable star 2 Cen (V806 Cen). Fourier analysis yields a more precise value of 12.57 d for the period of the brightness variation instead of 12.0 d. Light curves constructed from the photometric data…
Observational evidences of multiple shock waves in X-ray selected BL Lacerate objects
Kapanadze, B. Z.
The results of optical R-band photometry of three X-ray selected BL Lacertae objects 1ES 0502+675, 1ES 0806+524 and 1ES 1959+650 from the Einstein Slew Survey are presented. The observations are performed during 1997–2006 with the 70-cm meniscus type telescope of Abastumani Astrophysical Observatory. The objects show clear long-term variability wi…
Multiparametric infrared Tully-Fisher relation as a tool for mapping cosmic flows
Kashibadze, O. G.
The peculiar velocity field for 907 galaxies with heliocentric radial velocities VH ≤ 3000 km/s is examined. The data are divided into three samples, organized according to the principles behind the method for determining the distance to the galaxies: the luminosity of the tip of the red giant branch (TRGB), fluctuations in the surface …
Local dark energy: HST evidence from the vicinity of the M81/M82 galaxy group
Karachentsev, I. D.; Kashibadze, O. G.; Makarov, D. I. +5 more
The Hubble Space Telescope observations of the nearby galaxy group M81/M82 and its vicinity indicate that the dynamics of the expansion outflow around the group is dominated by the antigravity of the dark energy background. The local density of dark energy in the area is estimated to be near the global dark energy density or perhaps exactly equal …
X-ray emission of OH megamaser galaxies
Hambaryan, V. V.; Kandalyan, R. A.; Sabat, H. A.
The properties of OH megamaser galaxies in the x-ray region are discussed. Observational data from the XMM-Newton x-ray satellite are presented for three megamasers, IRAS 01418+1651, IRAS 11010+4107, and IRAS 13218+0552. Based on a sample of OH megamaser galaxies it is shown that the x-ray and OH emission are closely coupled. Megamaser emission al…
Masses of the local group and of the M81 group estimated from distortions in the local velocity field
Karachentsev, I. D.; Kashibadze, O. G.
Based on high precision measurements of the distances to nearby galaxies with the Hubble telescope, we have determined the radii of the zero velocity spheres for the local group, R0 = 0.96±0.03Mpc, and for the group of galaxies around M 81/M 82, 0.89±0.05Mpc. These yield estimates of MT = (1.29±0.14)· 1012 M⊙<…
Stellar Disks and Halos of Edge-on Spiral Galaxies: NGC 891, NGC 4144, and NGC 4244
Tikhonov, N. A.; Galazutdinova, O. A.
Stellar photometry of images from the ACS and WFPC2 cameras on the Hubble Space Telescope (HST) is used to study the star composition and spatial distribution of stars in three edge-on visible spiral galaxies: NGC 891, NGC 4144, and NGC 4244. Measurements of the surface number density of old stars revealed two stellar subsystems in these galaxies:…
Fluctuations in the Intensity of Radiation Emerging from a Multicomponent Stochastic Atmosphere. II
Nikoghossian, A. G.; Aboudarham, J.; Mouradian, Z.
This part of a series of papers examines the more general problem in which it is assumed that the fluctuations in the intensity of radiation emerging from a medium are caused by random variations in both the optical thickness of the structural elements and the power of the energy sources contained in them. The frequency dependence of the relative …
New Runaway O-stars Based on Data from HIPPARCOS
Mdzinarishvili, T. G.
12 new runaway O-stars are identified using an analysis of their proper motions based on data from HIPPARCOS. The peculiar tangential and total transverse velocities of these stars are determined. A list of the observed runaway stars is given.
The BM Ori System. I. Anomaly in the Radial Velocity
Klochkova, V. G.; Vitrichenko, E. A.
The radial velocities of the star BM Ori are determined from spectra obtained by the HST and IUE satellites, as well as from spectra obtained with the BTA telescope. An analysis of this data shows that the radial velocities of the main star and its satellite experience an irregular positive shift by ∼20-30 km/s. This fact can only be interpreted i…