most important scientific achievements for 2011–2017
Studying distributions of stars of different
ages in irregular and spiral galaxies we found for each galaxy a clear
correlation between the age of stars and the spatial size of the
subsystems of stars of this age. We believe that the dependency found
by us can
be explained by the hypothesis of galaxy expansion over time.
N., Galazutdinova O., AA Transac., V. 27, Iss.2, 227, 2012.
N., Galazutdinova O.,
Astronomy Letters, V.
38, Iss.3, p. 147, 2012.
Fig. 1. HST image of the PGC9962 galaxy (on top).
Hertzsprung-Russell diagram for this galaxy is shown with isochrones of different ages (in the bottom left corner)
and number density distribution diagrams for stars of different ages perpendicular to
disk plane (in the bottom right corner). The numbers on the diagrams denote the age of stars in millions of years.
NGC 1313 galaxy,
being, perhaps, the most
mysterious galaxy of the sky, has been studied based on the Hubble
Telescope images. In normal images, it looks like a normal spiral
but deep images show that the galaxy is highly distorted by
interaction. However, the images do not show any neighboring galaxy,
which would create the deformation of a stellar structure. We made a
photometry of eight NGC 1313 fields
of its dwarf companion AM 0319-662 and studied the visible distribution
of different ages and of metallicity in the galaxy. It has been found
spatial distribution of low metallicity stars is substantially
the distribution of high metallicity stars. This distinction has
us to identify the fragments of a dwarf galaxy destroyed by now, being
merged with NGC 1313. This disappeared galaxy was the cause of the
gravitational deformation of NGC 1313.
N., Galazutdinova O.,
Astronomy Letters, V. 42, Iss.7, p. 428, 201, 2016.
N., Galazutdinova O., Galaxy NGC 1313 mystery (poster), VAK-2017, Yalta, 17 September, 2017.
NGC 1313 (image made with 8 meter
3) We have developed the new
method for determining the size of groups and clusters of galaxies from cumulative distribution
of number of galaxies in
dependence on squared clustercentric distance. For 29 systems of galaxies we have determined
dynamical masses within the effective radius Re which are about 1.65 times less then masses enclosed within R200
radius. A comparison of the
inferred dynamical masses and the
hydrostatic masses determined from the radiation of hot gas in galaxy
groups and clusters (based on
published data) led us to conclude that the inferred masses for the
main sample of 21 groups and clusters, which does not include merging
clusters with irregular structure, the dynamical masses exceed the
X-ray masses an average by
12%, with an rms scatter of
A.I., Kopylova F.G., Astrophysical Bulletin, 70, Iss.3, p. 243,
Fig. 3. A comparison of
the X-ray masses (MX,200) obtained by gas radiation in
X-ray band with the dynamical masses (M200) measured from the radial velocities of galaxies. The objects of the main sample
are shown by filled circles.
4) We have developed a new method for determining the size of galaxy clusters, the region with a radius of Rh (or Rsp) (>R200), from the cumulative distribution of the number of galaxies depending on the squared clustercentric distance, where Rh (or Rsp)
radius of apocenter of orbits of galaxies. This allowed to determine
for the systems of galaxies the total K-luminosity and the number of
galaxies corrected for the background. K-luminosity, effective radius
containing either half of the luminosity, or half the number of
galaxies and dispersion of radial velocities of galaxy systems form a
Fundamental plane (FP) LK = Re0.70(N/2)×σ1.34.
In Schaefer et al. (MNRAS, L21, 263, 1993) (for comparison) for 16
clusters of galaxies in the filter V by another method is obtained the FP: LV = Re0.89×σ1.28.
Kopylova F.G., Kopylov
A.I., Astrophysical Bulletin, 71, Iss.3, p. 257,
Fig. 4. The Fundamental plane of galaxy groups and clusters in NIR range. The regression relation have the form of: LK = Re0.70(N/2)×σ1.34. The red circles show galaxy groups with σ < 420 km/s.
|5) Stellar photometry for three fields in the Virgo cluster of galaxies has
been performed on the basis of archival Hubble Space Telescope ACS/WFC images.
The densely populated red giant branches belonging to cluster galaxies are
seen on the constructed Hertzsprung-Russell diagrams. The distances to eight
galaxies in the Virgo cluster have been determined by the TRGB method (from
14 to 18 Mpc). The
sizes of the stellar subsystems and the gradients in the number density of
red giants along the galactic radius have been determined for the investigated
galaxies. The stellar periphery of the galaxies has been found to extend to
great distances and to cover the entire area of the images used. Therefore,
the stars that have previously been thought to be intracluster stars actually
belong to the periphery of neighboring galaxies.
Astronomy Letters, V. 43, Iss.1, p. 21, 2017.
5. Image of the galaxies LBS 31, NGC 4407 and VCC 871 in the DSS
review. The square F2 of the Hubble Space Telescope with the ACC/WFC
chamber is noted. The ellipses around NGC 4407 and VCC 871 mark the
visible boundaries of the star subsystems of these galaxies. It can be
seen that the subsystems overlap the HST image of the telescope and
make it impossible to search for intergalactic stars in this field. The
size of the picture is 10'×10', the north is at the top.
to the archives of the SDSS DR10 catalogue for clusters of galaxies
A1656 (Coma), A1139, A1314 (Leo supercluster), A2040, A2052, A2107
(Hercules supercluster) the specific star formation rate is determined.
We have obtained that the fraction of galaxies with quenched star
formation decreases continuously with a radius of 0.87±0.02 in the
center to 0.43±0.03 in the outskirts, beyond the Rsp. Thus
remains more, than in the field on average on 26%. We also found that
galaxies actively forming stars are, as a rule, on the outskirts of
clusters of galaxies and have dispersion of radial velocities more than
galaxies with quenched star formation.
Kopylov, A.I., Astrophysical Bulletin, 73, Iss.1, p. ?, 2018.
Variations of spatial distribution and kinematics of galaxies in
clusters depending on their specific star formation rate (log sSFR),
divided into 4 bins. The size of the symbols correspond to these bins:
large symbols – log sSFR = [–1.75,–1.35], [–1.35,–1.05] Gyr–1, small symbols – [–1.75,–4.00], [–4.00, all the rest] Gyr–1. Thus, large symbols mark the star formong galaxies, small – galaxies with quenched star formation.
7) On the basis of the Hubble Space Telescope images stellar photometry of nine fields around the
giant elliptical galaxy M87 from the Virgo cluster was performed to determine the
boundary of the influence of giant galaxies of groups and clusters on
neighboring dwarf galaxies. The populated branches of red giants and AGB stars are visible on the Hertzsprung-Russell diagrams. Distances to M87 for each field are determined based on the TRGB method. An
increase in the distance modulus is found when approaching the center
of the galaxy, indicating either the influence of high-metallic red
giants, or the existence of a weak gas-dust cloud around M87 with a
diameter of approximately 20' and maximum absorption in filter I to
0.18m near the center of the galaxy. The
average value of the distance modulus was determened as (m–M) = 30.93 by the outlying from the center
of the M87 fields, which corresponds to a distance D =
15.4 Mpc. This value puts M87 not in the center of the cluster, but on its near edge. The star subsystem of the galaxy is defined up to a distance of 190 kpc and has an even greater continuation. It is shown that the stars at this distance belong to the galaxy M87 and are not intergalactic stars, as previously thought. For
the first time distances to three dwarf galaxies were measured:
P4_anon, NGC4486A and VCCA039.These galaxies turned out to be M87 satellites.
Tikhonov N.A., Galazutdinova O., Karataeva G.M., Astrophysical Bulletin, 73, Iss.2, p.?, 2018.
Fig. 7. DSS-image of the Virgo cluster with galaxy M87.