排序方式： 共有33条查询结果，搜索用时 25 毫秒
1.
The giant lenticular galaxy NGC 80, which is the brightest member of a rich group, possesses a central evolutionarily-distinct region: the stars in the nucleus and in a circumnuclear ring of radius 5″t–7″ have a mean age of only 7 Gyr, whereas the stellar population of the bulge is older than 10 Gyr. The nucleus of NGC 80 is also chemically distinct: it is a factor of 2–2.5 richer in metals than its immediate neighborhood and is characterized by a high magnesium-to-iron abundance ratio [Mg/Fe]≈+0.3. The global stellar disk of NGC 80 has a two-tiered structure: its outer part has an exponential scale length of 11 kpc and normal surface density, while the inner disk, which is also exponential and axisymmetric, is more compact and brighter. Although the two-tiered structure and the chemically distinct nucleus obviously have a common origin and owe their existence to some catastrophic restructuring of the protogalactic gaseous disk, the origin of this remains unclear, since the galaxy lacks any manifestations of perturbed morphology or triaxiality. 相似文献
2.
V. S. Bychkova N. S. Kardashev V. V. Vlasyuk O. I. Spiridonova 《Astronomy Reports》2004,48(10):840-852
We monitored five active galactic nuclei in the R optical band with a CCD mounted on the 1-m Zeiss-1000 telescope of the Special Astrophysical Observatory from April 2001 to August 2003. Three sources displayed intraday variability on several nights. Stronger variability was detected on time scales from two days to a week. The two-year light curves are presented for four of the observed objects. 相似文献
3.
4.
5.
6.
D. V. Spiridonova S. V. Krivovichev V. N. Yakovenchuk Ya. A. Pakhomovsky 《Geology of Ore Deposits》2011,53(7):670-677
The Rb- and Sr-exchanged forms of ivanyukite have been obtained and structurally characterized. The chemical formulas derived from the electron microprobe data are as follows: the Rb-exchanged form (Na0.10K0.07Ca0.15Sr0.05Rb1.81Ba0.02)Σ = 2.20[(Ti3.65Nb0.19Fe0.05Mn0.01)Σ = 3.90O2.07/(OH)1.93(Si2.98Al0.02)Σ = 3.00 O12] · 3.61H2O; the Sr-exchanged form (K0.03Sr0.81Ca0.04Ba0.07)Σ = 0.95[(Ti3.74Nb0.19Fe0.03)Σ = 3.96] [O1.83/(OH)2.17](Si2.99Al0.01)Σ = 3.00O12) · 7H2O. The structures of the Rb- and Sr-exchanged forms of ivanyukite have been solved and refined using the least squares method. The structures are based on a mixed three-dimensional octahedral-tetrahedral framework of the pharmacosiderite type with channels occupied by Rb+ and Sr2+ cations and water molecules. The Rb+ cations in the Rb-exchanged form are 12-coordinated, whereas the Sr2+ cations in the Sr-exchanged form are 9- or 7-coordinated. The statistical investigation of the geometric parameters of the pharmacosiderite-type titanosilicates showed that symmetry changes are associated with the interactions of extraframework cations with the O atom of the Ti4(O,OH)4 clusters of the titanosilicate framework. The relationship between the unit-cell parameters in titanosilicates of the pharmacosiderite type and the structural geometric parameters of the titanosilicate framework has been proved by the use of multiple regression equations. 相似文献
7.
8.
V. V. Shimansky S. A. Pozdnyakova N. V. Borisov I. F. Bikmaev V. V. Vlasyuk O. I. Spiridonova A. I. Galeev S. S. Mel’nikov 《Astrophysical Bulletin》2009,64(4):349-364
We analyze the physical state and the properties of the close binary systems HS 1857+5144 and Abell 65. We took the spectra
of both systems over a wide range of orbital phases with the 6-m telescope of the Special Astrophysical Observatory of the
Russian Academy of Sciences (SAO RAS) and obtained their multicolor light curves with the RTT150 and Zeiss-1000 telescopes
of the SAO RAS. We demonstrate that both Abell 65 and HS 1857+5144 are young precataclysmic variables (PV) with orbital periods
of P
orb
= 1.
d
003729 and P
orb
= 0.
d
26633331, respectively. The observed brightness and spectral variations during the orbital period are due to the radiation
of the cold component, which absorbs the short-wave radiation of the hot component and reemits it in the visual part of the
spectrum. A joint analysis of the brightness and radial velocity curves allowed us to find the possible and optimum sets of
their fundamental parameters. We found the luminosity excesses of the secondary components of HS 1857+5144 and Abell 65 with
respect to the corresponding Main Sequence stars to be typical for such objects. The excess luminosities of the secondary
components of all young PVs are indicative of their faster relaxation rate towards the quiescent state compared to the rates
estimated in earlier studies. 相似文献
9.
We present the results of optical monitoring of the blazar 2007 + 777 on the 60-cm Zeiss-600 reflector of the Special Astrophysical Observatory of the Russian Academy of Sciences. Light curves in the B and V bands obtained from August 8, 2000, through May 25, 2001, reveal variability with characteristic time scales from 10 to 40 days. 相似文献
10.
V. S. Bychkova A. E. Volvach L. N. Volvach N. S. Kardashev M. G. Larionov V. V. Vlasyuk O. I. Spiridonova A. Lähteenmäki M. Tornikoski J. Tammi E. Järvelä R. J. C. Vera W. Chamani S. Enestam 《Astrophysical Bulletin》2018,73(3):293-297
The active core of the galaxy AO0235+164 is monitored in the optical and radio bands at millimeter wavelengths. Using the multifrequency data obtained in gamma, optical and radio bands, the characteristics of its radiation in the active phase of 2015–2016 are studied. The cross-correlation method was used to determine the delays of the 2015 flare that took place in AO0235+164 in different bands. The analysis made it possible to establish that, in comparison with the previous flare phenomena, changes in the orientation of the emissions (jets) have occurred. The angle θ between the jets and the direction towards the observer has decreased by a factor of \(\sqrt 2 \), resulting in a twofold increase in the γ-factor. The obtained value γ ≈ 40 is the most extreme value ever observed in AO0235+164 over the entire span of observations. 相似文献