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1.
We investigated the properties of galaxy clusters in the region of the Hercules supercluster using observational data from the SDSS and 2MASS catalogs and the NED. We have selected 13 galaxy clusters with a total dynamical mass of 4.82 × 1015 M ⊙ in a 100 × 45 Mpc supercluster region in the plane of the sky (0.030 < z < 0.041). In addition, our sample includes eight clusters from the immediate neighborhoods of the superclusters and ten field clusters at the same z. The derived properties of the rich Hercules supercluster are shown in comparison with the data for the poor Leo supercluster. The main parameters of the virialized galaxy cluster regions in the near infrared (K s ) for the Hercules supercluster differ from those for the Leo supercluster: the number of galaxies and the total luminosity (to a limiting magnitude of ?21 · m 5) increase with cluster mass (L K,200 ∝ M 200 0.91±0.07 and N 200 ∝ M 200 0.94±0.07 ), but the dependences are steeper by 0.28 and 0.22. In the virialized cluster regions, the fraction of early-type galaxies selected by the bulge contribution, concentration index, and u t= r color is, on average, 66% (60% in Leo, 70% in the field) among the galaxies brighter than ?23 · m 3 and 54% (51% in Leo, 61% in the field) among the galaxies brighter than ?22 · m 3. The fraction of early-type galaxies in the superclusters does not change with galaxy cluster mass and luminosity. The composite luminosity function of the rich Hercules supercluster is described by a Schechter function and does not differ from the luminosity function of the poor Leo supercluster for the luminosity interval [?26 m , ?21 · m 5] but differs from the field luminosity function at the same z determined from ten galaxy clusters. 相似文献
2.
We analyze the properties of the clusters of galaxies in the region of the Ursa Major (UMa) supercluster using observational data from SDSS and 2MASS catalogs. The region studied includes a supercluster (with a galaxy and cluster overdensity of 3 and 15, respectively) and field clusters inside the 150-Mpc diameter surrounding region. The total dynamical mass of 10 clusters of galaxies in UMa is equal to 2.25 × 1015 M ⊙, and the mass of 11 clusters of galaxies in the UMa neighborhood is equal to 1.70 × 1015 M ⊙. The fraction of early-type galaxies brighter than M K * + 1 in the virialized regions of clusters is, on the average, equal to 70%, and it is virtually independent on the mass of the cluster. The fraction of these galaxies and their average photometric parameters are almost the same both for UMa clusters and for the clusters located in its surroundings. Parameters of the clusters of galaxies, such as infrared luminosities up to a fixed magnitude, the mass-to-luminosity ratio, and the number of galaxies have almost the same correlations with the cluster mass as in other samples of galaxies clusters. However, the scatter of these parameters for UMa member clusters is twice smaller than the corresponding scatter for field clusters, possibly, due to the common origin of UMa clusters and synchronized dynamical evolution of clusters in the supercluster. 相似文献
3.
Using an apparent-magnitude limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 7(SDSS DR7), we investigate
the correlation between morphologies and luminosity for the Main galaxy sample. Our Main galaxy sample is divided into two
classes: Main galaxies only with TARGET_GALAXY flag (bestPrimtarget = 64), and ones also with other flags. It is found that
for the second class Main galaxies, the early-type proportion monotonously increases with increasing luminosity nearly in
the whole luminosity region. But for the first class Main galaxies, the early-type proportion increases with increasing luminosity
only within a certain luminosity region (−22.2 < M
r
< −19.8). In the high luminosity region (M
r
< −22.2), the early-type proportion of the first class Main galaxies even decreases dramatically with increasing luminosity.
We also analyze the correlation between morphologies and luminosity of galaxies around the peak of the redshift distribution
( 0.07 ≤ z ≤ 0.08 ). In such a narrow redshift region, we still observe strong correlation between morphologies and luminosity,
which shows that this correlation is fundamental. 相似文献
4.
We present the results of our study of the peculiar motions for 41 galaxy clusters and groups in the regions of the Hercules and Leo superclusters (0.027 < z < 0.045). For this purpose, based on SDSS (Data Release 8) data, we compiled a sample of early-type galaxies in the investigated clusters and groups, constructed their fundamental planes (FPs), and determined independent distances and peculiar velocities. The Hubble law between the radial velocities galaxy clusters and the distances derived from the FPs holds for the rich Hercules supercluster as a whole. At the same time, however, significant peculiar motions along the line of sight with rms deviations of 736 ± 50 and 584 ± 50 km s?1 are observed within this supercluster and in its immediate neighborhood. In the poor Leo supercluster, the rms deviation is also large, 625 ± 70 km s?1. Its Hubble diagram exhibits the approach of galaxy clusters and groups along the line of sight relative to the most massive cluster A1185. In the immediate neighborhood of the Leo supercluster (virtually in its field), the rms deviation of the peculiar velocities is minimal, 287 ± 60 km s?1. 相似文献
5.
We have investigated the peculiar motions of clusters of galaxies in the Ursa Major (UMa) supercluster and its neighborhood. Based on SDSS (Sloan Digital Sky Survey) data, we have compiled a sample of early-type galaxies and used their fundamental plane to determine the cluster distances and peculiar velocities. The samples of early-type galaxies in the central regions (within R 200) of 12 UMa clusters of galaxies, in three main subsystems of the supercluster—the filamentary structures connecting the clusters, and in nine clusters from the nearest UMa neighborhood have similar parameters. The fairly high overdensity (3 by the galaxy number and 15 by the cluster number) suggests that the supercluster as a whole is gravitationally bound, while no significant peculiar motions have been found: the peculiar velocities do not exceed the measurement errors by more than a factor of 1.5–2. The mean random peculiar velocities of clusters and the systematic deviations from the overall Hubble expansion in the supercluster are consistent with theoretical estimates. For the possible approach of the three UMa subsystems to be confirmed, the measurement accuracy must be increased by a factor of 2–3. 相似文献
6.
David G. Russell 《Journal of Astrophysics and Astronomy》2009,30(2):93-118
The value of Hubble parameter (H0) is determined using the morphologically type dependent Ks-band Tully-Fisher Relation (K-TFR). The slope and zero point are
determined using 36 calibrator galaxies with ScI morphology. Calibration distances are adopted from direct Cepheid distances,
and group or companion distances derived with the Surface Brightness Fluctuation Method or Type Ia Supernova. It is found
that a small morphological type effect is present in the K-TFR such that ScI galaxies are more luminous at a given rotational
velocity than Sa/Sb galaxies and Sbc/Sc galaxies of later luminosity classes. Distances are determined to 16 galaxy clusters
and 218 ScI galaxies with minimum distances of 40.0 Mpc. From the 16 galaxy clusters a weighted mean Hubble parameter of H0 = 84.2 ± 6 km s−1 Mpc−1 is found. From the 218 ScI galaxies a Hubble parameter of H0 = 83.4 ± 8 km s−1 Mpc−1 is found. When the zero point of K-TFR is corrected to account for recent results that find a Large Magellanic Cloud distance
modulus of 18.39±0.05, a Hubble parameter of 88.0 ± 6 km s−1 Mpc−1 is found. Effects from Malmquist bias are shown to be negligible in this sample as galaxies are restricted to a minimum rotational
velocity of 150 km s−1. It is also shown that the results of this study are negligibly affected by the adopted slope for the K-TFR, inclination
binning, and distance binning. A comparison with the results of the Hubble Key Project (Freedman et al. 2001) is made. Discrepancies between the K-TFR distances and the HKP I-TFR distances are discussed. Implications for Λ-CDM
cosmology are considered with H0 = 84 km s−1 Mpc−1. It is concluded that it is very difficult to reconcile the value of H0 found in this study with ages of the oldest globular
clusters and matter density of the universe derived from galaxy clusters in the context of Λ-CDM cosmology. 相似文献
7.
We study the variations of the properties of groups of galaxies with dynamical masses of 1013 M ⊙<M 200<1014 M ⊙, represented by two samples: one has redshifts of z < 0.027 and is located in the vicinity of the Coma cluster, the other has z > 0.027, and is located in the regions of the following superclusters of galaxies: Hercules, Leo, Bootes, Ursa Major, and Corona Borealis. Using the archived data of the SDSS and 2MASX catalogs, we determined the concentration of galaxies in the systems by measuring it as the inner density of the group within the distance of the fifth closest galaxy from the center brighter than M K = ?23. m 3. We also measured the magnitude gap between the first and the fourth brightest galaxies ΔM 14 located within one half of the selected radius R 200, the fraction of early-type galaxies, and the ratio of bright dwarf galaxies (Mr = [?18. m 5,?16. m 5]) to giant galaxies (M r < ?18. m 5) (DGR) within the radius R 200. The main aim of the investigation is to find among these characteristics the ones that reflect the evolution of groups of galaxies.We determined that the ratio of bright dwarf galaxies to early-type giant galaxies on the red sequence depends only on the x-ray luminosity: the DGR increases with luminosity. The fraction of early-type galaxies in the considered systems is equal, on average, to 0.65 ± 0.01, and varies significantly for galaxies with σ200 < 300 kms?1. Based on the luminosity of the brightest galaxy, the magnitude gap between the first and the fourth brightest galaxies in the groups, and on model computations of these parameters, we selected four fossil group candidates: AWM4, NGC0533, NGC0741, and NGC6098 (where the brightest galaxy is a double).We observe no increase in the number of faint galaxies (the α parameter of the Schechter function is less than 1) in our composite luminosity function (LF) for galaxy systems with z < 0.027 in the M K = [?26m,?21. m 5] range, whereas earlier we obtained α > 1 for the LF of the Hercules and Leo superclusters of galaxies. 相似文献
8.
We present results of the study of peculiar motions of 57 clusters and groups of galaxies in the regions of the Corona Borealis (CrB), Bootes (Boo), Z5029/A1424, A1190, A1750/A1809 superclusters of galaxies and the galaxy clusters located beyond massive structures (0.05 < z < 0.10). Using the SDSS (Data Release 8) data, a sample of early-type galaxies was compiled in the systems under study, their fundamental planes were built, and relative distances and peculiar velocities were determined. Within the galaxy superclusters, significant peculiar motions along the line of sight are observed with rms deviations of 652 ± 50 kms?1—in CrB, 757 ± 70 kms?1—in Boo. In the most massive A2065 cluster in the CrB supercluster, no peculiar velocity was found. Peculiar motions of the other galaxy clusters can be caused by their gravitational interaction both with A2065 and with the A2142 supercluster. It has been found that there are two superclusters projected onto each other in the region of the Bootes supercluster with a radial velocity difference of about 4000 kms?1. In the Z 5029/A1424 supercluster near the rich Z5029 cluster, the most considerable peculiar motions with a rms deviations of 1366 ± 170 kms?1 are observed. The rms deviations of peculiar velocities of 20 clusters that do not belong to large-scale structures is equal to 0 ± 20 kms?1. The whole sample of the clusters under study has the mean peculiar velocity equal to 83 ± 130 kms?1 relative to the cosmic microwave background. 相似文献
9.
A radio survey, using the Very Large Array at 20 and 90 cm λ has been carried out in the direction of 46 distant Abell clusters
(0.1 ≲ z ≲ 0.3) dominated by a cD galaxy (clusters classified to be Bautz-Morgan I type). A radio source coincident with the
cD galaxy was detected in 16 clusters. We find that the radio luminosity function of the cD galaxies at 20cm λ, and below
the luminosityP
1.4ghz ≲ 1024.5 W Hz-1, is similar to that of brightest ellipticals in less clustered environments. Above this luminosity, the cDs seem to have
a higher probability of becoming radio sources. The effect of optical brightness on radio emission is shown to be the same
for the two classes. No significantly large population of very-steep-spectrum sources with spectral index α >1.2 (flux density
∝ frequency-α) was found to be associated with cD galaxies. A significant negative correlation is found between the radio luminosity of
the cD galaxy and the cooling-time of the intra cluster medium near the galaxy. We also present evidence that the probability
of radio emission from first-ranked galaxies is dependent upon their location relative to the geometrical centres of clusters
and thus related to the morphological class and the evolutionary state of the clusters. We argue that both these effects are
primarily caused by the dynamical evolution of these distant clusters of galaxies. 相似文献
10.
We investigate the distribution and velocity field of galaxies situated in a band of 100 by 20 degrees centered on M87 and oriented along the Local supercluster plane. Our sample amounts 2158 galaxies with radial velocities less than 2000 km s?1. Of them, 1119 galaxies (52%) have distance and peculiar velocity estimates. About 3/4 of early-type galaxies are concentrated within the Virgo cluster core, most of the late-type galaxies in the band locate outside the virial radius. Distribution of gas-rich dwarfs with MHI >M* looks to be insensitive to the Virgo cluster presence. Among 50 galaxy groups in the equatorial supercluster band 6 groups have peculiar velocities about 500–1000 km s?1 comparable with virial motions in rich clusters. The most cryptic case is a flock of nearly 30 galaxies around NGC4278 (Coma I cloud), moving to us with the mean peculiar velocity of ?840 km s?1. This cloud (or filament?) resides at a distance of 16.1 Mpc from us and approximately 5 Mpc away from the Virgo center. Galaxies around Virgo cluster exhibit Virgocentric infall with an amplitude of about 500 km s?1. Assuming the spherically symmetric radial infall, we estimate the radius of the zero-velocity surface to be R0 = (7.0±0.3) Mpc that yields the total mass of Virgo cluster to be (7.4 ± 0.9)× 1014M⊙ in tight agreement with its virial mass estimates. We conclude that the Virgo outskirts does not contain significant amounts of dark mater beyond its virial core. 相似文献
11.
A. Fritz B.L. Ziegler R.G. Bower I. Smail R.L. Davies 《Astrophysics and Space Science》2003,285(1):61-66
We explore the evolution of the early-type galaxy population in the rich cluster Abell 2390 at z=0.23. For this purpose, we have obtained spectroscopic data of 51 elliptical and lenticular galaxies with MOSCA at the 3.5
m telescope on Calar Alto Observatory. As our investigation spans both a broad range in luminosity (–22.3≤MB≤–:19.3)and a wide field of view (10′×10′), the environmental dependence of different formation scenarios can be analysed
in detail as a function of radius from the cluster center. In this paper, we present first results on the Faber-Jackson relation
and, for a subsample of 14 galaxies with morphological and structural parameters from HST, we also investigate the evolution
of the Kormendy relation and the Fundamental Plane. We find a mild luminosity evolution of the early-type galaxies in Abell
2390: our objects are on average brighter by m
B∼0.4 mag.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
12.
We investigate the variation of the fraction of galaxies with suppressed star formation (MK < ?21 . m 5) and early-type galaxies (fracE) of the “red sequence” along the projected radius in six galaxy clusters:Coma (A1656), A1139, and A1314 in the Leo supercluster region (z ≈ 0.037) and A2040, A2052, A2107 in the Hercules supercluster region (z ≈ 0.036). According to SDSS (DR10) data, fracE is the highest in the central regions of galaxy clusters and it is, on the average, equal to 0.62 ± 0.03, whereas in the 2–3R/R200c interval and beyond the Rsp ≈ 0.95 ± 0.04 R200m radius that we inferred from the observed profile fracE is minimal and equal to 0.25 ± 0.02. This value coincides with the estimate fracE = 0.24 ± 0.01 that we inferred for field galaxies located between the Hercules and Leo superclusters at the same redshifts. We show that the fraction of galaxies with suppressed star formation decreases continuously with cluster radius from 0.87 ± 0.02 in central regions down to 0.43 ± 0.03 in the 2–3 R/R200c interval and beyond Rsp, but remains, on the average, higher than 26% than the corresponding fraction for field objects. This decrease is especially conspicuous in the galaxy mass interval log M* [M⊙] = 9.5–10. We found that galaxies with ongoing star formation have average clustercentric distances 1.5–2.5 R/R200c and that their radial-velocity dispersions are higher than those of galaxies with suppressed star formation. 相似文献
13.
We report the results of study of the A1569 cluster (12
h
36m.3, +16°35′) and the neighboring A1589 cluster (12
h
41m.3, +18°34′), making up a pair (a supercluster) with a projected size of about 10Mpc. This study is done within the framework
of our program for investigating the galaxy clusters with bimodal velocity distributions (i.e., clusters where the velocities
of subsystems differ by more than Δcz ∼ 3000 km/s). In the A1569 cluster we have identified two subsystems: A1569A (cz = 20613 km/s) and A1569B (cz = 23783 km/s). These subsystems have the line-of-sight velocity dispersions of 484 km/s and 493 km/s, and dynamic masses
within the R
200 radius equal to 1.8 × 1014 and 2.0 × 1014
M
⊙, respectively. We directly estimate the distances to these subsystems using three methods applied to earlytype galaxies:
the Kormendy relation, photometric plane, and fundamental plane. To this end, we use the results of our observations made
with the 1-m telescope of the SAO RAS and the data adopted from the SDSS DR7 catalog. We found that A1569 consists of two
independent clusters. The A1569B cluster is located at the Hubble distance corresponding to its radial velocity. The A1569A
cluster has a peculiar velocity of −1290 ± 630 km/s, which can be explained by the effect of the more massive A1589 cluster
(with a mass of 7.9 × 1014
M
⊙) and of the supercluster where it resides. In all the four bimodal clusters that we studied within the framework of our program,
A1035, A1775, A1831, and A1569, the subsystems are independent clusters lying close to the Hubble relation between redshift
and distance. 相似文献
14.
We present R-band galaxy luminosity functions (GLFs) from aspectroscopic sample of six nearby rich galaxy clusters. In addition
to individual cluster GLFs, extending to, in one case, M
R=–14, we also present composite GLFs for cluster and field galaxies toM
R=–17. All six cluster samples are consistent with the composite GLF, but there is evidence that the GLF of the quiescent population
in clusters is not universal. Furthermore, the GLF of quiescent galaxies is significantly steeper in clusters than in the
field. The overall GLF in clusters is consistent with that of field galaxies, except for the luminous tip, which is enhanced
in clusters versus the field.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Daniel Thomas Ralf Bender Ulrich Hopp Claudia Maraston Laura Greggio 《Astrophysics and Space Science》2003,284(2):599-602
We present kinematics and stellar population properties of 17 dwarf early-type galaxies in the luminosity range -14 ≥ M
B ≥ -19. Our sample fills the gap between the intensively studied giant elliptical and Local Group dwarf spheroidal galaxies.
The dwarf ellipticals of the present sample have constant velocity dispersion profiles within their effective radii and do
not show significant rotation, hence are clearly anisotropic. The dwarf lenticulars, instead, rotate faster and are, at least
partially, supported by rotation. From optical Lick absorption indices, we derive metallicities and element abundances. Combining
our sample with literature data of the Local Group dwarf spheroidals and giant ellipticals, we find a surprisingly tight linear
correlation between metallicity and luminosity over a wide range: -8 ≥ M
B ≥ -22. The α/Fe ratios of our dwarf ellipticals are significantly lower than the ones of giant elliptical galaxies, which
is in agreement with spectroscopy of individual stars in Local Group dwarf spheroidals. Our results suggest the existence
of a clear kinematic and stellar population dichotomy between dwarf and giant elliptical galaxies. This result is important
for theories of galaxy formation, because it implies that present-day dwarf ellipticals are not the fossiled building blocks
of giant ellipticals.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
The relationship between the rotation curves for the galaxies and the distribution of mass and angular momentum within the
galaxies is examined. The theory of angular momentum transfer is applied to the observed properties of the galaxies. The coupling
between the dynamical mass of a spiral galaxy and its luminosity is studied. Most of the spiral galaxies in subclusters surrounding
NGC 4889, NGC 4874, and NGC 4839 in the Coma cluster are galaxies that have lower luminosities, with MB fainter than −21m.5. These galaxies are characterized by a higher mass-to-luminosity ratio than that of the galaxies with higher luminosities
MB brighter than −21m.5, which suggests the presence of a large fraction of dark matter in the spiral galaxies of the subclusters.
Translated from Astrofizika, Vol. 52, No. 1, pp. 75–84 (February 2009). 相似文献
17.
Gian Luigi Granato Laura Silva Luigi Danese Giulia Rodighiero Alberto Franceschini Gianni Fasano Alessandro Bressan 《Astrophysics and Space Science》2001,276(2-4):973-978
We summarize our modelling of galaxy photometric evolution (the GRASIL code). By including the effects of dust grains and
PAH molecules in a two-phase clumpy medium, where clumps are associated with star-forming regions, we reproduce the observed
UV to radio SEDs of galaxies with star formation rates from zero to several hundred M
⊙ yr-1.GRASIL is a powerful tool for investigating star formation, the initial mass function and the supernova rate in nearby starbursts
and normal galaxies, as well as for predicting the evolution of luminosity functions of different types of galaxies at wavelengths
covering six decades. It may be interfaced with any device to provide the star formation and metallicity histories of a galaxy.
As an application, we have investigated the properties of early-type galaxies in the HDF, tracking the contribution of this
population to the cosmic star formation history, which has a broad peak between z = 1.5 and 4.To explain the absence of objects at z ≳ 1.3, we suggest a sequence of dust-enshrouded merger-driven starbursts in the first few Gyr of galaxy lifetimes. We are
at present working on a complementary sample of late-type objects selected in a similar way.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
J. Iglesias-Páramo A. Boselli J.M. VÍlchez L. Cortese G. Gavazzi 《Astrophysics and Space Science》2002,281(1-2):419-420
We present a deep wide field Hα imaging survey of the central regions of the two nearby clusters of galaxies Coma and Abell
1367, taken with the WFC at the INT 2.5m telescope. We determine for the first time the Schechter parameters of the Hα luminosity
function (LF) of cluster galaxies. The Hα LFs of Abell 1367 and Coma are compared with each other. Typical parameters of φ
≈ 100.00±0.07 Mpc-3, L
*≈ 1041.25±0.05 erg sec-1 and α ≈ -0.70±0.10 are found for both clusters.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
19.
We study the A1831 cluster within the framework of our program of the investigation of galaxy clusters with bimodal velocity
distributions (i.e., clusters where the velocities of subsystems differ by more than Δ
cz
∼ 3000 km/s).We identify two subsystems in this cluster: A1831A (cz = 18970 km/s) and A1831B (cz = 22629 km/s) and directly estimate the distances to these subsystems using three methods applied to early-type galaxies:
the Kormendy relation, the photometric plane, and the fundamental plane. To this end, we use the results of our observations
made with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the data adopted
from the SDSS DR6 catalog. We confirmed at a 99% confidence level that (1) the two subsystems are located at different distances,
which are close to their Hubble distances, and (2) the two subsystems are located behind one another along the line of sight
and are not gravitationally bound to each other. Both clusters have a complex internal structure, which makes it difficult
to determine their dynamical parameters. Our estimates for the velocity dispersions and masses of the two clusters: 480 km/s
and 1.9 × 1014
M
⊙ for A1831A, 952 km/s and 1.4 × 1015
M
⊙ for A1831B should be views as upper limits. At least three spatially and kinematically distinct groups of galaxies can be
identified in the foreground cluster A1831A, and this fact is indicative of its incomplete dynamical relaxation. Neither can
we rule out the possibility of a random projection. The estimate of the mass of the main cluster A1831B based on the dispersion
of the line-of-sight velocities of galaxies is two-to-three times greater than the independent mass estimates based on the
total K-band luminosity, temperature, and luminosity of the X-ray gas of the cluster. This fact, combined with the peculiarities
of its kinematical structure, leads us to conclude that the cluster is in a dynamically active state: galaxies and groups
of galaxies with large line-of-sight velocities relative to the center of the cluster accrete onto the virialized nucleus
of the cluster (possibly, along the filament directed close to the line of sight). 相似文献
20.
We present the results of our observational study of two candidates for polar-ring galaxies (PRGs). Both objects, A2330-3751
and SDSS J000911.57-003654.7, are giant edge-on galaxies with large-scale structures resembling polar rings observed along
their minor axes. The optical diameter of the putative ring reaches 60 kpc in A2330-3751 and 18 kpc in SDSS J000911.57-003654.7.
To estimate the space density of PRGs, we have constructed their luminosity function in the range of B-band absolute magnitudes from −17·
m
5 to −21·
m
5. We have found that ∼10−3 of the nearby galaxies exhibit polar structures. Polar rings around early-type (E/S0) galaxies are encountered approximately
a factor of 3 more frequently than those around spiral ones. According to our estimates, ∼20–30 PRGs in which large-scale
rings are seen almost face-on must be observed among relatively bright galaxies (B ≤ 15
m
). 相似文献