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1.
To study the spatial distribution of galaxies lying between the Virgo cluster and the Local Group, a search was made for probable nearby galaxies. Using the method of brightest stars and of blue and red supergiants made it possible to determine the distances to 24 galaxies, among which six relatively nearby galaxies were identified. The results of the distance determinations showed that the maximum in the number distribution of galaxies lies at 17.0 Mpc, which we take as the distance to the Virgo cluster. Using the difference between the distance moduli of two clusters of galaxies, in Virgo and Coma Berenices, from literature sources and the velocity of the latter cluster, we determined the Hubble constant to be H 0 = 77 ± 7 km·sec–1·Mpc–1.  相似文献   

2.
We present SALT spectroscopy of a globular cluster in the center of the nearby isolated dSph galaxy KKs3 situated at a distance of 2.12 Mpc. Its heliocentric radial velocity is 316 ± 7 km s–1 that corresponds to VLG = 112 km s–1 in the Local Group (LG) reference frame. We use its distance and velocity along with the data on other 35 field galaxies in the proximity of the LG to trace the local Hubble flow. The following basic properties of the local field galaxies are briefly discusse: morphology, absolute magnitudes, average surface brightnesses, specific star formation rates, and hydrogen mass‐to‐stellar mass ratios. Surprisingly, the sample of the neighboring isolated galaxies displays no signs of compression under the influence of the expanding Local Void. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

3.
The distance modulus of the Virgo cluster has been reexamined based on the Tully-Fisher relation between fully corrected B. 1 0 values and 21 cm velocity width derived from RC3 catalogue for spiral galaxies of Sbc-Sdm types, belonging to the “low-velocity” Virgo subcluster, singled out according to the statistical method proposed by Anosova, and led to the value μ = 31.15 ± 0.57 mag. A strong dependence of the intrinsic scatter in the Tully-Fisher relation on the apparent axes ratio of galaxies has been found, with a value of 0.4 mag for strongly flattened, highly inclined galaxies and galaxies with small inclinations and a value of 0.72 mag for objects with intermediate values of axes ratio. The restriction to samples only with galaxies with photoelectric observations does not lead to a considerable change of amplitude of scatter and decreases the value the of distance modulus. Published in Astrofizika, Vol. 42, No. 1, pp. 37–46, January–March, 1999.  相似文献   

4.
The peculiarities of non-Hubble bulk motions of galaxies are studied by analyzing a sample of 1271 thin edge-on spirals with distances determined using a multiparametric Tully-Fisher relation that includes the amplitude of the galaxy rotation, the blue and red diameters, surface brightness, and morphological type. In the purely dipole approximation, the bulk motion of galaxies relative to the cosmic microwave background frame can be described by the velocity of 336±96 km s?1 in the direction l=321°, b=?1° within radius R max =10000 km s?1. An analysis of more complex velocity field models shows that the anisotropy of the Hubble expansion described by the quadrupole term is equal to ～5% on scale lengths R max=6000–10000 km s?1. The amplitude within the Local Supercluster (R max=3000 km s?1) is as high as ～20%. The inclusion of the octupole component reduces the dipole amplitude to 134±111 km s?1 on scale lengths of ～8000 km s?1. The most remarkable feature of the galaxy velocity field within R max=8000 km s?1 is the zone of minimum centered on l=80°, b=0° (the constellation of Cygnus) whose amplitude reaches 18% of the mean Hubble velocity.  相似文献   

5.
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   

6.
The most accurate data on galaxy types, corrected apparent magnitudes and redshifts as given in the Sandage-TammanRevised Shapley-Ames catalog are analyzed. It is shown that Sb galaxies of the same luminosity class as M31 and M81 define a narrow Hubble relation withH 0=65 –6 +15 km s–1 Mpc–1.In contrast, Sc galaxies deviate strongly towars higher redshift from a linear, log redshift—apparent magnitude relation. Not all this deviation can be selection effect due to increasing volume sampled at increasing redshift (Malmquist bias). Physical associations of groups of galaxies in theRSA Catalog are used to establish the existence of various amounts of excess (non-velocity) redshifts among Sc and allied types of galaxies.Independent distances fromHi line width — luminosity criterion (Tully-Fisher) are analyzed. It is shown that this criterion gives much smaller distances than redshifts do for galaxies which deviate above the Hubble line. Unless the Tully-Fisher relation gives too small distances for more luminous galaxies, this confirms the excess redshift to be intrinsic to the Galaxy. But it is next demonstrated, that for low redshift galaxies, there is no discrepancy between redshift and Tully-Fisher distance even though there is a wide range of absolute magnitudes.If Tully-Fisher distances are accepted, the onlly alternative to having a Hubble constant which increases strongly with distance is to have a component of the higher redshift Sc's contributed by a non-recessional redshift. Streaming motions would have to be large, increase with distance and be always in the receding sence. It is shown here that the Sc's which deviate most from the Hubble relation and have the largest discrepancies with Tully-Filsher distances lie predominantly in the sky toward very nearby groups of galaxies. If they were at these closer distances the discordant galaxies, mostly ScI's, would have dwarfish physical properties but not so unprecedented as the large sizes which result from redshift distances.Finally the interaction of specific high redshift ScI's with nearby galaxies is presented as an independent proof that ScI's are generally small, low luminosity galaxies. This result furnishes insight into the long standing puzzle of how apparently distant ScI's can interact with nearby galaxies such as in Stephan's Quintet, Seyfert's Sextet and NGC 4151/4156.  相似文献   

7.
Kormendy’s relation (μe-logR e) is used to investigate the structure of the compact Ursa Major supercluster of galaxies (11h30m+55°, cz=18 000 km s?1); this relation allows the distances of early-type galaxies to be estimated. The relative distances of 13 clusters in the supercluster and their peculiar velocities are determined with a mean statistical accuracy of 6%. In general, the supercluster obeys the Hubble relation between radial velocity and distance. However, there is reason to suggest that the supercluster consists of two subsystems with mean radial velocities of 16 200 and 19 700 km s?1. For a velocity dispersion in the subsystems of ～1100 km s?1, the fact that each of them is gravitationally bound is not ruled out.  相似文献   

8.
The Tully–Fisher Relationship (TFR) is utilized to identify anomalous redshifts in normal spiral galaxies. Three redshift anomalies are identified in this analysis: (1) several clusters of galaxies are examined, in which late type spirals have significant excess redshifts relative to early-type spirals in the same clusters; (2) galaxies of morphology similar to ScI galaxies are found to have a systematic excess redshift relative to the redshifts expected if the Hubble Constant is 72 km s−1 Mpc−1; (3) individual galaxies, pairs, and groups are identified which strongly deviate from the predictions of a smooth Hubble flow. These redshift deviations are significantly larger than can be explained by peculiar motions and TFR errors. It is concluded that the redshift anomalies identified in this analysis are consistent with previous claims for large non-cosmological (intrinsic) redshifts.  相似文献   

9.
BUSS observations of the profiles of two well observed spectral lines in the ultraviolet spectrum of CMi (Procyon; F5 IV–V) are analysed with a Fourier transform method in order to determine values of various parameters of the velocity field of the upper photosphere. We find a microturbulent line-of-sight velocity componentL = 0.9 ± 0.4 km s–1, a macroturbulent velocity componentL M = 5.3 ± 0.2 km s–1, and a rotational velocity componentv R sini=10.0±1.2 km s–1. In these calculations a single-moded sinusoidal isotropic macroturbulent velocity function was assumed. The result appears to be sensitive to the assumed shape of the macroturbulence function: for an assumed Gaussian shape the observations can be described withv R sini=4 km s–1 andL M = 11.6 ± 2.7 km s–1. A comparison is made with other results and theoretical predictions.  相似文献   

10.
The GMRTHI 21 cm-line observations of galaxies in the Eridanus group are presented. The Eridanus group, at a distance of ≈ 23 Mpc, is a loose group of ≈200 galaxies. The group extends to more than 10 Mpc in projection. The velocity dispersion of the galaxies in the group is ≈240 km s−1. The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E + S0) and 70% (Sp + Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for ≈ 200 h. HI emission was detected from 31 galaxies. The channel rms of ≈ 1 mJy beam−1 was achieved for most of the image-cubes made with 4 h of data. The corresponding HI column density sensitivity (3σ) is ≈ 1 × 1020 cm−2 for a velocity-width of ≈ 13.4 km s−1. The 3σ detection limit of HI mass is ≈ 1.2 X 107 Mpd for a line-width of 50 km s−1. Total HI images, HI velocity fields, global HI line profiles, HI mass surface densities, HI disk parameters and HI rotation curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies. These data will be used to study the HI and the radio continuum properties, the Tully-Fisher relations, the dark matter halos, and the kinematical and HI lopsidedness in galaxies.  相似文献   

11.
The search for non thermal radio emission from clusters of galaxies is a powerful tool to investigate the existence of magnetic fields on such large scale. Unfortunately, such observations are scarce thus far, mainly because of the very faint large scale radio emission expected in clusters of galaxies. In the present contribution we will first review the status of the radio observations of clusters of galaxies, carried out with the aim of detecting large scale radio emission.We will then focus on the large scale radio emission detected at 327 MHz and 610 MHz in the Coma cluster of galaxies. The features of the detected radio emission suggest that a magnetic field with an intensity of the order of ~ 10–7 Gauss must be present on a scale of about 2 Mpc (forH o = 100km s –1 Mpc –1). The morphology of the radio emission is similar to that of the most recent X-ray images derived with ROSAT, and follows the distribution of the galaxies in the cluster. All these pieces of information will be taken into account in the discussion on the possible origin of this large scale magnetic field.  相似文献   

12.
Photometry of HD 155638=V792 Her has been analyzed to determine the elements of this totally eclipsing RS CVn binary. The light variation outside eclipse was found to have a period of 27d.07±0d.07, which is slightly different from the 27d.5384±0d.0045 orbital period. Analysis of the eclipses was achieved by a modification of the Russell-Merrill technique. With the aid of radial velocity measures, absolute elements were obtained for the hot and cool stars, respectively;R h=2.58R ,R c=12.28R ,M h=1.40M ,M c=1.46M ,i=80o.61 and velocity semi-amplitudesK c=48.36 km s–1±0.79 km s–1, andK h=50.50 km s–1±0.33 km s–1. The apparent magnitudes areV h=9 m .73 andV c=8 m .48. The distance to HD 155638 was estimated to be 310 parsecs.  相似文献   

13.
Using the recently completed Giant Meterwave Radio Telescope, we have detected the HI 21 cm-line absorption from the peculiar galaxy C153 in the galaxy cluster Abell 2125. The HI absorption is at a redshift of 0.2533, with a peak optical depth of 0.36. The full width at half minimum of the absorption line is 100 km s−1. The estimated column density of atomic Hydrogen is 0.7×1022(T s /100) cm−2. The HI absorption is redshifted by ∼400km s−1 compared to the [OIII] emission line from this system. We attribute this to an infalling cold gas or to an out-flowing ionised gas, or to a combination of both as a consequence of tidal interactions of C153 with either a cluster galaxy or the cluster potential.  相似文献   

14.
In the region of the formation of weak and medium-strong lines, the microturbulence increases with height (V ver=0.7–0.9 km s-1, V hor= 1.1–1.5 km s-1), the macroturbulence decreases (V ver=1.6–1.4 km s-1, V hor= 2.4–1.5 km s-1), and the total velocity field (vertical component) is depth-independent (1.7 km s-1). The empirical damping constants for Fe, Ti, Cr, Ni lines are equal 1.36, 1.76, 1.66, 1.66, respectively. The correlation length (the Kubo-Anderson process has been used) in the solar photosphere is 520–550 km.  相似文献   

15.
This paper deals with the observed variation in the flattening of galaxies with the density of galaxies in the subclusters of Coma surrounding NGC 4889, NGC 4874, and NGC 4839 based on data from the Abastumani Combined Catalog of Galaxies. The mean values of the observed ratios of the diameters of the galaxies, as well as histograms of their distributions, indicate that in the central, dense regions of the subclusters within a volume of 0.5h 75 −1 Mpc3, E and S0 type galaxies are close to spheroidal. A significant reduction in the mean values of the diameters of the galaxies in the subclusters is noted, regardless of their morphology relative to the galaxies in the halo of the Coma cluster. In the subclusters, spiral galaxies are found with a hydrogen deficit that is more than 5 times the hydrogen deficit in spirals within the halo of the cluster. According to their 3-D coordinates, most of the galaxies with a hydrogen deficit are located closer to the south-east edge of the subcluster surrounding NGC 4874 near an extended gas filament in the x-ray region. This may indicate that the subcluster is moving toward a central condensation of faint galaxies in the Coma cluster and a possible merger with it. __________ Translated from Astrofizika, Vol. 50, No. 3, pp. 355–368 (August 2007).  相似文献   

16.
The sky distribution of deviations from the mean Hubble relation for the brightest galaxies in clusters is non-random for the velocity range 4000<V r<25 000 km s–1. Deviations in visual magnitude are mainly positive in one large region of the sky and mainly negative in another region; the difference between the regions is 0.37±0.08 m and is independent of colour. Various explanations are discussed briefly, and galactic or intergalactic absorption may be excluded.  相似文献   

17.
The Tully–Fisher relationship (TFR) has been shown to have a relatively small observed scatter of ∼±0.35 mag implying an intrinsic scatter < ±0.30 mag. However, when the TFR is calibrated from distances derived from the Hubble relation for field galaxies scatter is consistently found to be ±0.64 to ±0.84 mag. This significantly larger scatter requires that intrinsic TFR scatter is actually much larger than ±0.30 mag, that field galaxies have an intrinsic TFR scatter much larger than cluster spirals, or that field galaxies have a velocity dispersion relative to the Hubble flow in excess of 1000 km s−1. Each of these potential explanations faces difficulties and contradicted by available data and the results of previous studies. An alternative explanation is that the measured redshifts of galaxies are composed of a cosmological redshift component predicted from the value of the Hubble constant and a superimposed intrinsic redshift component previously identified in other studies. This intrinsic redshift component may exceed 5000 km s−1 in individual galaxies. In this alternative scenario a possible value for the Hubble constant is 55–60 km s−1 Mpc−1.  相似文献   

18.
In the course of investigation of Shakhbazian compact groups we studied the group ShCG 191 which has been identified also as the Abell cluster A1097. By its richness it may be classified as a rich compact group or a poor cluster. We determined redshifts of 14 objects in the area of the cluster and found that two of the supposed members of the group are stars. Redshifts of 12 galaxies show that the system is gravitationally bound. The V and R magnitudes of 23 member galaxies and their morphological types are determined. We present in this paper also the surface brightness contours of member galaxies in the central area of the cluster, the curves of isophotal twisting and the Fourier parameter a4. It is shown that some galaxies in the cluster are interacting with each other. Physical parameters of the group are close to those of ShCGs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

19.
We present an analysis of the chiral property of 667 spiral and barred spiral galaxies in the Local Supercluster (radial velocity <3 000 km s−1). The arms of a galaxy (spiral or barred spiral) can be distinguished according to their orientation (leading or trailing) relative to the direction of the rotation. We use environment of each galaxy as a subsample in order to study the chiral property of galaxies. In addition, equatorial position angle distributions of leading and trailing arm galaxies are studied. We classify our database according as their morphology, diameters, radial velocities, axial ratios and magnitudes. The distribution of trailing and leading arm galaxies in the Local Supercluster is found homogeneous. A significant dominance of either trailing or leading structures is noticed within the Virgo cluster region, suggesting that the aggregation of these structures might have already started there. The rotation axes of the galaxies in the Virgo cluster is found to lie in the equatorial plane. Chirality of galaxies is found strong for the subsamples that showed a random alignment in the equatorial position angle distribution. Possible explanations of the results will be presented.  相似文献   

20.
We use a new expanded and partially modified sample of 1501 thin edge-on spiral galaxies from the RFGC catalog to analyze the non-Hubble bulk motions of galaxies on the basis of a generalized multiparameter Tully-Fisher relation. The results obtained have confirmed and refined our previous conclusions (Parnovsky et al. 2001), in particular, the statistical significance of the quadrupole and octupole components of the galaxy bulk velocity field. The quadrupole component, which is probably produced by tidal forces from overdense regions, leads to a difference in the recession velocities of galaxies on scales of 8000–10000 km s?1 up to 6% of their Hubble velocity. On Local Supercluster scales (3000 km s?1), its contribution increases to about 20%. Including the octupole components in the model causes the dipole component to decrease to the 1σ level. In contrast, in the dipole model, the galaxy bulk velocity relative to the frame of reference of the cosmic microwave background is 310±75 km s?1 toward the apex with l=311° and b=12°. We also consider a sample of 1493 galaxies that was drawn using a more stringent galaxy selection criterion. The difference between the results of our data analysis for this sample and for the sample of 1501 galaxies is primarily attributable to a decrease in the dipole velocity component (290±75 km s?1 toward the apex with l=310° and b=12°) and a decrease in σ by about 2%.  相似文献   

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