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Searching for possible siblings of the sun from a common cluster based on stellar space velocities
Bobylev, V. V.; Bajkova, A. T.; Mylläri, A. +1 more
We propose a kinematic approach to searching for the stars that could be formed with the Sun in a common "parent" open cluster. The approach consists in preselecting suitable candidates by the closeness of their space velocities to the solar velocity and analyzing the parameters of their encounters with the solar orbit in the past in a time interv…
Hard X-ray bursts recorded by the IBIS telescope of the INTEGRAL observatory in 2003-2009
Grebenev, S. A.; Chelovekov, I. V.
To find X-ray bursts from sources within the field of view of the IBIS/INTEGRAL telescope, we have analyzed all the archival data of the telescope available at the time of writing the paper (the observations from January 2003 to April 2009). We have detected 834 hard (15-25 keV) X-ray bursts, 239 of which were simultaneously recorded by the JEM-X/…
Application of vector spherical harmonics for kinematic analysis of stars from zonal catalogues
Tsvetkov, A. S.; Vityazev, V. V.
We solve the problem on a kinematic analysis of the three-dimensional velocity field of stars from zonal catalogues, i.e., catalogues in which the stars are presented at all right ascensions in some declination zones. We have constructed a system of vector spherical harmonics with the properties of completeness and orthogonality for a chosen decli…
The red giant branch in the Tycho-2 catalogue
Gontcharov, G. A.
Based on multicolor photometry from the 2MASS and Tycho-2 catalogues, we have produced a sample of 38 368 branch red giants that has less than 1% of admixtures and is complete within 500 pc of the Sun. The sample includes 30 671 K giants, 7544Mgiants, 49 C giants, and 104 suspected supergiants or S stars. The photometric distances have been calcul…
Pitch angles of distant spiral galaxies
Savchenko, S. S.; Reshetnikov, V. P.
We have studied the pitch angles of spiral arms for 31 distant galaxies at z ∼ 0.7 from three Hubble Deep Fields (HDF-N, HDF-S, HUDF). Using the pitch angle-rotation velocity relation calibrated from nearby galaxies, we have estimated the rotation velocities of galaxies from the deep fields. These estimates have a low accuracy (∼50 km s-1
On the characteristics of tidal structures of interacting galaxies
Reshetnikov, V. P.; Mohamed, Y. H.; Sotnikova, N. Ya.
We present the results of our analysis of the geometrical tidal tail characteristics for nearby and distant interacting galaxies. The sample includes more than two hundred nearby galaxies and about seven hundred distant ones. The distant galaxies have been selected in several deep fields of the Hubble Space Telescope (HDF-N, HDF-S, HUDF, GOODS, GE…
Stars and clusters of the coma galaxies NGC 4921 and NGC 4923
Tikhonov, N. A.; Galazutdinova, O. A.
Based on deep Hubble Space Telescope ACS/WFC images, we have performed stellar photometry for the spiral and lenticular galaxies NGC 4921 and NGC 4923 in the Coma cluster. The derived Hertzsprung-Russell diagrams show that, apart from the stellar population, NGC 4921 has several thousand globular clusters. The asymmetry of their apparent distribut…
Statistics of interacting galaxies at z ∼ 0.7
Reshetnikov, V. P.; Mohamed, Y. H.
We present the results of our analysis of the frequencies of galaxies with tidal tails and M51-type galaxies in several deep fields of the Hubble Space Telescope (HDF-N, HDF-S, HUDF, GOODS, GEMS). In total, we have found about seven hundred interacting galaxies at redshifts z ≤ 1.5 in these fields. At z ≤ 0.7, the observed space densities of galax…