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1.
We present the results of a search for companions around the isolated galaxies from the 2MIG catalog. Among 3227 2MIG galaxies we detected 125 objects with a total of 214 neighbors having radial velocity differences of ΔV < 500 km/s and projected separations of R p < 500 kpc relative to the 2MIG galaxies. The median luminosity of the companions is 1/25 of the luminosity of catalog galaxies, which has little effect on the dynamic isolation of the latter. The median ratio of the orbital mass to the K-luminosity determined from 60 companions of E and S0 2MIG galaxies, 63M ⊙/L ⊙, is significantly greater than that found from the spiral galaxy companions (17M ⊙/L ⊙). We note that a fraction of 2MIG galaxies with companions may be a part of low-contrast diffuse structures: clouds and filaments.  相似文献   

2.
The absolute proper motions of about 275 million stars from the Kharkov XPM catalog have been obtained by comparing their positions in the 2MASS and USNO-A2.0 catalogs with an epoch difference of about 45 yr for northern-hemisphere stars and about 17 yr for southern-hemisphere stars. The zero point of the system of absolute proper motions has been determined using 1.45 million galaxies. The equatorial components of the residual rotation vector of the ICRS/UCAC2 coordinate system relative to the system of extragalactic sources have been determined by comparing the XPM and UCAC2 stellar proper motions: ω x,y,z = (−0.06, 0.17, −0.84) ± (0.15, 0.14, 0.14) mas yr−1. These parameters have been calculated using about 1 million faintest UCAC2 stars with magnitudes R UCAC2 > 16 m and J > 14 m . 7, for which the color and magnitude equation effects are negligible.  相似文献   

3.
We present a catalog of 520 most isolated nearby galaxies with angular velocities V LG < 3500 km/s, covering the entire sky. This population of “space orphans” makes up 4.8% among 10 900 galaxies with measured radial velocities. We describe the isolation criterion used to select our sample, called the “Local Orphan Galaxies”(LOG), and discuss their basic optical and HI properties. A half of the LOG catalog is occupied by the Sdm, Im and Ir morphological type galaxies without a bulge. The median ratio M gas/M star in the LOG galaxies exceeds 1. The distribution of the catalog galaxies on the sky looks uniform with some signatures of a weak clustering on the scale of about 0.5 Mpc. The LOG galaxies are located in the regions where the mean local density of matter is approximately 50 times lower than the mean global density. We indicate a number of LOG galaxies with distorted structures, which may be the consequence of interaction of isolated galaxies with massive dark objects.  相似文献   

4.
We analyze the properties of galaxy clusters in the region of the Leo supercluster using observational data from the SDSS and 2MASS catalogs. We have selected 14 galaxy clusters with a total dynamical mass of 1.77 × 1015 M ⊙ in the supercluster region 130 by 60 Mpc in the plane of the sky (z ≃ 0.037). The composite luminosity function of the supercluster is described by a Schechter function with parameters that, within the error limits, correspond to field galaxies and does not differ from the luminosity function of the richer Ursa Major (UMa) supercluster for the same luminosity range (the bright end). The luminosity functions of early-type and late-type galaxies in Leo at the faint end are characterized by a sharp decrease (α = −0.60±0.08) and a steep increase (α = −1.44± 0.10) in the number of galaxies, respectively. In the virialized cluster regions, the fraction of early-type galaxies selected by the u-r color, bulge contribution, and concentration index among the galaxies brighter than M K * + 1 is, on average, 62%. This fraction is smaller than that in the UMa supercluster at a 2–3σ level. The near-infrared luminosities of galaxy clusters down to a fixed absolute magnitude correlate with their masses almost in the same way as for other samples of galaxy clusters (L 200,K ∝ M 2000.63±0.11)).  相似文献   

5.
The radial velocities are measured for 45 galaxies located in the neighborhoods of 29 likely isolated galaxies in a new catalog. We find that about 85% of these galaxies actually are well isolated objects. 4% of nearby galaxies with V LG < 3500 km/s are this kind of cosmic "orphan" Translated from Astrofizika, Vol. 52, No. 2, pp. 203–210 (May 2009).  相似文献   

6.
Automated search for star clusters in J, H, K s data from 2MASS catalog has been performed using the method developed by Koposov et al. (2008). We have found and verified 153 new clusters in the interval of the galactic latitude −24° < b < 24°. Color excesses E(B − V), distance moduli and ages were determined for 130 new and 14 yet-unstudied known clusters. In this paper, we publish a catalog of coordinates, diameters, and main parameters of all the clusters under study. A special web-site available at has been developed to facilitate dissemination and scientific usage of the results.  相似文献   

7.
We analyze the statistical properties of normal galaxies to be detected in the all-sky survey by the eROSITA X-ray telescope of the Spectrum-X-Gamma observatory. With the current configuration and parameters of the eROSITA telescope, the sensitivity of a 4-year-long all-sky survey will be ≈10?14 erg s?1 in the 0.5–2 keV band. This will allow ～(1.5–2) × 104 normal galaxies with approximately the same contribution of star-forming and elliptical galaxies to be detected. All galaxies of the X-ray survey are expected to enter into the existing far-infrared (IRAS) or near-infrared (2MASS) catalogs; the sample of star-forming galaxies will be approximately equivalent in sensitivity to the sample of star-forming galaxies in the IRAS catalog of infrared sources. Thus, a large homogeneous sample of normal galaxies with measured X-ray, near-infrared, and far-infrared fluxes will be formed. About 90% of the galaxies in the survey are located within ～200–400 Mpc. A typical (most probable) galaxy will have a luminosity log L X ～ 40.5–41.0, will be located at a distance of ～70–90 Mpc, and will be either a star-forming galaxy with a star formation rate of ～20M ⊙ yr?1 whose X-ray emission is produced by ultraluminous X-ray sources (ULXs) or an elliptical galaxy with amass log M * ～ 11.3 emitting through to a hot interstellar gas. The galaxies within 35 Mpc will collectively contain ～102 ULXs with luminosities log L X > 40, ～80% of whichwill be the only luminous source in the galaxy. Thus, although the angular resolution of the eROSITA telescope is too low for the luminosity function of compact sources in galaxies to be studied in detail, the survey data will allow one to investigate its bright end and, possibly, to impose constraints on the maximum luminosity of ULXs.  相似文献   

8.
The determination of the supernova (SN) rate is based not only on the number of detected events, but also on the properties of the parent galaxy population. This is the first paper of a series aimed at obtaining new, refined, SN rates from a set of five SN surveys, by making use of a joint analysis of near-infrared (NIR) data. We describe the properties of the 3838 galaxies that were monitored for SNe events, including newly determined morphologies and their DENIS, and POSS-II/UKST I, 2MASS and DENIS J and Ks and 2MASS H magnitudes. We have compared 2MASS, DENIS and POSS-II/UKST IJK magnitudes in order to find possible systematic photometric shifts in the measurements. The DENIS and POSS-II/UKST I band magnitudes show large discrepancies (mean absolute difference of 0.4 mag.), mostly due to different spectral responses of the two instruments, with an important contribution (0.33 mag rms) from the large uncertainties in the photometric calibration of the POSS-II and UKST photographic plates. In the other wavebands, the limiting near infrared magnitude, morphology, and inclination of the galaxies are the most influential factors which affect the determination of photometry of the galaxies. Nevertheless, no significant systematic differences have been found between any pair of NIR magnitude measurements, except for a few percent of galaxies showing large discrepancies. This allows us to combine DENIS and 2MASS data for the J and Ks filters. Published in Astrofizika, Vol. 52, No. 1, pp. 47–62 (Februay 2009).  相似文献   

9.
FIRST and NVSS radio maps are used to cross identify the radio sources of the RCR catalog, which is based on observational data obtained in several runs of the “Cold” survey, with the SDSS and DPOSS digital optical sky surveys and the 2MASS, LAS UKIDSS, and WISE infrared surveys. Digital images in various filters and the coadded gri-band SDSS images, red and infrared DPOSS images, JHK-band UKIDSS images, and JHK-band 2MASS images are analyzed for the sources with no optical candidates found in the above catalogs. Our choice of optical candidates was based on the data on the structure of the radio source, its photometry, and spectroscopy (where available). We found reliable identifications for 86% of the radio sources; possible counterparts for 8% of the sources, and failed to find any optical counterparts for 6% of the sources because their host objects proved to be fainter than the limiting magnitude of the corresponding surveys. A little over half of all the identifications proved to be galaxies; about one quarter were quasars, and the types of the remaining objects were difficult to determine because of their faintness. A relation between the luminosity and the radioloudness index was derived and used to estimate the 1.4 and 3.94 GHz luminosities for the sources with unknown redshifts. We found 3% and 60% of all the RCR radio sources to be FRI-type objects (L ? 1024 W/Hz at 1.4 GHz) and powerful FRII-type galaxies (L ? 1026.5 W/Hz), respectively, whereas the rest are sources including objects of the FRI, FRII, and mixed FRI-FRII types. Unlike quasars, galaxies show a trend of decreasing luminosity with decreasing flux density. Note that identification would be quite problematic without the software and resources of the virtual observatory.  相似文献   

10.
We study the infrared (K s band) properties of clusters of galaxies in the Ursa Major supercluster using data from 2MASS (Two-Micron All-Sky Survey) and SDSS (Sloan Digital Sky Survey). We identified three large filaments with mean redshifts of z = 0.051, 0.060, and 0.071. All clusters of the supercluster are located in these filaments. We determined the total K s-band luminosities and masses for 11 clusters of galaxies within comparable physical regions (within a radius R 200 close to the virial radius) using a homogeneous method. We constructed a combined luminosity function for the supercluster in this region, which can be described by the Schechter function with the following parameters: M K * = ?24.50 and α = ?0.98. The infrared luminosities of the clusters of galaxies correlate with their masses; the M/L K ratios of the systems increase with their masses (luminosities), with most of the Ursa Major clusters of galaxies (particularly the richer ones) closely following the relations derived previously for a large sample of clusters and groups of galaxies. The total mass-to-infrared-luminosity ratio is 52 M ⊙/L ⊙ for six Abell clusters and 49M ⊙/L ⊙ for all of the clusters, except Anon2.  相似文献   

11.
We analyze empirical relationships between optical, near infrared, and HI characteristics of isolated galaxies from the 2MIG Catalog covering the entire sky. Data on morphological types, K S −, and B-magnitudes, linear diameters, HI masses, and rotational velocities are examined. The regression parameters, dispersions, and correlation coefficients are calculated for pairs of these characteristics. The resulting relationships can be used to test the hierarchical theory of galaxy formation through numerous mergers of cold dark matter.  相似文献   

12.
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   

13.
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   

14.
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   

15.
We describe the procedure we used to compile a catalog of the proper motions of 23 633 stars in the sky area covering about 700 square degrees at the north Galactic pole. The compiled catalog combines the data from the UCAC2, Tycho-2, and FONAC catalogs for stars down to V ～ 14 m in this sky area. In addition to proper motions, the catalog also contains the near-infrared magnitudes J, H, and K s in the 2MASS system. The mean accuracy is 2.5 mas/yr for proper motions and 0.03 m for magnitudes.  相似文献   

16.
Based on data from the Two-Micrometer All-Sky Survey (2MASS), we analyzed the infrared properties of 451 Local-Volume galaxies at distances D ≤ 10 Mpc. We determined the K-band luminosity function of the galaxies in the range of absolute magnitudes from ?25m to ?11m. The local luminosity density within 8 Mpc is 6.8 × 108L⊙ Mpc?3, a factor of 1.5 ± 0.1 higher than the global mean K-band luminosity density. We determined the ratios of the virial mass to the K-band luminosity for nearby groups and clusters of galaxies. In the luminosity range from 5 × 1010 to 2 × 1013L⊙, the dependence log(M/LK) ∝ (0.27 ± 0.03) log LK with a dispersion of ～0.1 comparable to the measurement errors of the masses and luminosities of the systems of galaxies holds for the groups and clusters of galaxies. The ensemble-averaged ratio, 〈M/LK〉 ? (20–25) M⊙/L⊙, was found to be much smaller than the expected global ratio, (80–90)M⊙/L⊙, in the standard model with Ωm = 0.27. This discrepancy can be eliminated if the bulk of the dark matter in the Universe is not associated with galaxies and their systems.  相似文献   

17.
The present paper is devoted to the construction of a catalog of isolated galaxy pairs extracted from the HyperLEDA extragalactic database. The radial velocities of the galaxies in the pairs are in the range [3000, 16000] km s?1. In order to get an unbiased pair catalog as complete as possible, we have limited the absolute magnitude of the galaxies to M ≤ ?18.5. The criteria used to define the isolated galaxy pairs are the following: 1) velocity criterion: radial velocity difference between the pair members ΔV < 500 kms?1; 2) interdistance criterion: projected distance between the members rp < 1 Mpc; 3) reciprocity criterion: each member is the closest galaxy to the other one, which excludes multiplets; 4) isolation criterion: we define a pair as isolated if the ratio ρ = r3/rp of the projected distance of the pair to its closest galaxy (this one having a velocity difference lower than 500 km s?1 with respect to the pair) and the members projected interdistance rp is larger than 2.5.We have searched for these closest galaxies first in HyperLEDA M-limited source catalog, then in the full one.We have managed not to suppress the small number of pairs having close-by but faint dwarf galaxy companions. The galaxy pair catalog lists the value of ρ for each isolated pair. This method allows the user of the catalog to select any isolation level (beyond the chosen limit ρ > 2.5). Our final catalog contains 13 114 galaxy pairs, of which 57% are fairly isolated withρ > 5, and 30% are highly isolated with ρ ≥ 10.  相似文献   

18.
We have used the Very Large Array to image a single field in a set of adjacent frequency bands around 333.0 MHz in an attempt to detect 21 cm emission from large scale H I inhomogeneities at a redshift of z = 3.3. Following the subtraction of continuum radio sources, the absence of any spectral signals apart from that expected due to the system thermal noise has been used to derive constraints on the evolutionary scenario leading to the formation of the present day clusters of galaxies. The observations rule out the existence of H I protoclusters atz = 3.3 with masses ≃3.5 × 1014 M ⊙ in H I gas and space density exceeding (74 Mpc)−3. This indicates that the present day rich clusters of galaxies either formed as gaseous protocluster condensates prior toz = 3.3 or else they formed through the clustering of their constituent galaxies.  相似文献   

19.
We investigate numerically the chemodynamical evolution of major disc–disc galaxy mergers in order to explore the origin of the mass-dependent chemical, photometric and spectroscopic properties observed in elliptical galaxies. We investigate especially the dependence of the fundamental properties on merger progenitor disc mass (M d). Three main results are obtained in this study:– More massive (luminous) ellipticals formed by galaxy mergers between more massive spirals have higher metallicity (Z) and thus show redder colours; the typical metallicity ranges from ∼ 1.0 solar abundance (Z∼ 0.02) for ellipticals formed by mergers with M d = 1010 M ⊙to ∼ 2.0 solar (Z∼ 0.04) for those with M d= 1012 M ⊙.– Both the Mg2 line index in the central part of ellipticals (R ≤ 0.1 R e) and the radial gradient of Mg2 (δ Mg2 / δ log R) are more likely to be larger for massive ellipticals. δ Mg2 / δ log R correlates reasonably well with the central Mg2 in ellipticals. For most of the present merger models, ellipticals show a positive radial gradient of the Hβ line index. – Both M/L B and M/L K (where M, L B, and L K are the total stellar mass of galaxy mergers, the B-band and the K-band luminosities, respectively) depend on galactic mass in such a way that more massive ellipticals have larger M/L B and smaller M/L K. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

20.
A V-band nova search was carried out in NGC 3627 with archival Hubble Space Telescope WFPC2 data which was obtained in the period between November 1997 and January 1998. A total of four novae candidates were discovered which corresponds to a global nova rate of R = 83.65 ± 7.58 yr−1. Taking into account the K-band luminosity obtained from 2MASS (Jarrett et al., 2003) yielded a luminosity specific nova rate (LSNR) of νK = 9.60 ± 1.64 novae per year per 1010L⊙,K. Excluding one of the candidates which may be a long-period variable leads to a LSNR of νK = 7.20 ± 1.23 novae per year per 1010L⊙,K. These values are higher than other known nova rates for external galaxies except the Magellanic Clouds.  相似文献   

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