Upload your image
DSS Images Other Images
Submit a new article
|Chandra Observations of Diffuse Gas and Luminous X-Ray Sources around the X-Ray-bright Elliptical Galaxy NGC 1600|
We observed the X-ray-bright E3 galaxy NGC 1600 and nearby members ofthe NGC 1600 group with the Chandra X-Ray Observatory ACIS-S3 to studytheir X-ray properties. Unresolved emission dominates the observation;however, we resolved some of the emission into 71 sources, most of whichare low-mass X-ray binaries associated with NGC 1600. Twenty-one of thesources have LX>2×1039 ergss-1 (0.3-10.0 keV; assuming they are at the distance of NGC1600), marking them as ultraluminous X-ray point source (ULX)candidates; we expect that only 11+/-2 are unrelatedforeground/background sources. NGC 1600 may have the largest number ofULX candidates in an early-type galaxy to date; however, cosmic variancein the number of background active galactic nuclei cannot be ruled out.The spectrum and luminosity function (LF) of the resolved sources aremore consistent with sources found in other early-type galaxies thanwith sources found in star-forming regions of galaxies. The source LFand the spectrum of the unresolved emission both indicate that there area large number of unresolved point sources. We propose that thesesources are associated with globular clusters (GCs) and that NGC 1600has a large GC specific frequency. Observations of the GC population inNGC 1600 would be very useful for testing this prediction. Approximately50%-75% of the unresolved flux comes from diffuse gaseous emission. Thespectral fits, hardness ratios, and X-ray surface brightness profile allpoint to two gas components. We interpret the soft inner component(a<~25'', kT~0.85 keV) as the interstellar medium of NGC1600 and the hotter outer component (a>~25'', kT~1.5 keV)as the intragroup medium of the NGC 1600 group. The X-ray image showsseveral interesting structures. First, there is a central region ofexcess emission that is roughly cospatial with Hα and dustfilaments immediately west of the center of NGC 1600. There appear to beholes in the X-ray emission to the north and south of the galaxy centerthat are roughly coincident with the lobes of the NGC 1600 radio source.On larger scales, there is excess emission to the northeast, which wesuggest may indicate the center of the group potential. The group galaxyNGC 1603 shows a tail of X-ray emission to its west that is probably dueto ram pressure stripping.
|Kinematical data on early-type galaxies. V.|
We present kinematical data for a sample of 26 galaxies. Rotation curvesand velocity-dispersion profiles are determined for all objects. This isour fifth paper in a series devoted to the presentation of data onelliptical and S0 galaxies, derived from long-slit absorptionspectroscopy; the series now gathers 119 galaxies with homogeneous data.Based on observations collected at the Observatoire de Haute-Provence.Tables 2 and 3 are presented in electronic form only; Tables 1 through 3are available from the CDS, Strasbourg, via anonymous ftp tocdsarc.u-strasbg.fr (184.108.40.206) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies|
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
|A catalogue of Mg_2 indices of galaxies and globular clusters|
We present a catalogue of published absorption-line Mg_2 indices ofgalaxies and globular clusters. The catalogue is maintained up-to-datein the HYPERCAT database. The measurements are listed together with thereferences to the articles where the data were published. A codeddescription of the observations is provided. The catalogue gathers 3541measurements for 1491 objects (galaxies or globular clusters) from 55datasets. Compiled raw data for 1060 galaxies are zero-point correctedand transformed to a homogeneous system. Tables 1, 3, and 4 areavailable in electronic form only at the CDS, Strasbourg, via anonymousftp 220.127.116.11. Table 2 is available both in text and electronic form.
|Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies|
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
|The fundamental plane of early-type galaxies: stellar populations and mass-to-light ratio.|
We analyse the residuals to the fundamental plane (FP) of ellipticalgalaxies as a function of stellar-population indicators; these are basedon the line-strength parameter Mg_2_ and on UBVRI broad-band colors, andare partly derived from new observations. The effect of the stellarpopulations accounts for approximately half the observed variation ofthe mass-to-light ratio responsible for the FP tilt. The residual tiltcan be explained by the contribution of two additional effects: thedependence of the rotational support, and possibly that of the spatialstructure, on the luminosity. We conclude to a constancy of thedynamical-to-stellar mass ratio. This probably extends to globularclusters as well, but the dominant factor would be here the luminositydependence of the structure rather than that of the stellar population.This result also implies a constancy of the fraction of dark matter overall the scalelength covered by stellar systems. Our compilation ofinternal stellar kinematics of galaxies is appended.
|A Catalog of Stellar Velocity Dispersions. II. 1994 Update|
A catalog of central velocity dispersion measurements is presented,current through 1993 September. The catalog includes 2474 measurementsof 1563 galaxies. A standard set of 86 galaxies is defined, consistingof galaxies with at least three reliable, concordant measurements. It issuggested that future studies observe some of these standard galaxies sothat different studies can be normalized to a consistent system. Allmeasurements are reduced to a normalized system using these standards.
|Spectroscopy and photometry of elliptical galaxies. III - UBV aperture photometry, CCD photometry, and magnitude-related parameters|
Photoelectric aperture photometry of nearly 2000 individual observationsof 449 elliptical galaxies combined with published measurements usingthe self-consistent UVB color catalog developed by Burstein et al.(1987) are presented. The data are placed on a standard magnitude andcolor system, and 'total' magnitudes and effective diameters are derivedby comparison with the standard elliptical magnitude growth curve. Agraphical representation of the standard growth curve and the residualsfrom it for each galaxy are given, and a new diameter measurement Dn ispresented which can be measured reliably for elliptical galaxies andserves as an accurate distance indicator when combined with centralvelocity dispersion. Individual magnitudes, surface brightnesses,effective diameters, and values of Dn are summarized for each galaxy incatalog form.
|Spectroscopy and photometry of elliptical galaxies. II - The spectroscopic parameters|
Radial velocities, velocity dispersions, and Mg line-strength indicesare measured for 469 elliptical galaxies using four telescope/detectorconfigurations. The data have been put on a common scale; the scatter ofrepeat measurements indicates an uncertainty of + or - 10 percent and +or - 0.01 mag for single determinations of sigma and Mg2, respectively.A correction for the change in linear aperture size as a function ofdistance has been derived, and mean corrected values of sigma and Mg2are adopted. The galaxies have been assigned to groups by combining thepresent velocities with those in the redshift catalog of Huchra et al.(1983) and using the algorithm of Huchra and Geller (1982).
|A Survey of Elliptical Galaxies at 6 CM|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1973A&A....24..247E&db_key=AST
Submit a new link
Member of following groups:
Observation and Astrometry data
Catalogs and designations: