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|The gas content of peculiar galaxies: Counterrotators and polar rings|
This paper studies the global ISM content in a sample of 104 accretinggalaxies, including counterrotators and polar rings, which spans theentire Hubble sequence. The molecular, atomic and hot gas content ofaccretors is compared to a newly compiled sample of normal galaxies. Wepresent results of a small survey of the J=1-0 line of 12COwith the 15 m SEST telescope on a sample of 11 accretors (10counterrotators and 1 polar ring). The SEST sample is enlarged withpublished data from 48 galaxies, for which observational evidence ofcounterrotation in the gas and/or the stars has been found. Furthermore,the available data on a sample of 46 polar ring galaxies has beencompiled. In order to explore the existence of an evolutionary pathlinking the two families of accretors, the gas content ofcounterrotators and polar rings is compared. It was found that thenormalized content of cold gas (Mgas/LB) in polarrings is ~ 1 order of magnitude higher than the reference value derivedfor normal galaxies. The inferred gas masses are sufficient to stabilizepolar rings through self-gravity. In contrast, it was found that thecold gas content of counterrotators is close to normal for all galaxytypes. Although counterrotators and polar rings probably share a commonorigin, the gas masses estimated here confirm that light gas ringsaccreted by future counterrotators may have evolved faster than theself-gravitating structures of polar rings. In this scenario, thetransformation of atomic into molecular gas could be enhanced near thetransition region between the prograde and the retrograde disks,especially in late-type accretors characterized by a high content ofprimordial gas. This is tentatively confirmed in this work: the measuredH2/HI ratio seems larger in counterrotators than in normal orpolar ring galaxies for types later than S0s. Based on observationscollected at SEST telescope, European Southern Observatory, La Silla,Chile. Table 1 is only available in electronic form athttp://www.edpsciences.org
|A neutral hydrogen survey of polar ring galaxies. III. Nançay observations and comparison with published data|
A total of 50 optically selected polar ring galaxies, polar ring galaxycandidates and related objects were observed in the 21-cm H i line withthe Nançay decimetric radio telescope and 31 were detected. Theobjects, selected by their optical morphology, are all north ofdeclination -39o, and generally relatively nearby (V< 8000km s-1) and/or bright (mB< 15.5). The H i linedata are presented for all 74 galaxies observed for the survey with theEffelsberg, Green Bank or Nanç radio telescopes, as well as allother published H i line parameters of these objects. Three objects wereobserved and detected by us at Parkes. A total of 59 objects weredetected. For each object a brief description is given based on aliterature search.
|Arcsecond Positions of UGC Galaxies|
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
|Molecular gas in polar-ring galaxies|
We present CO J=1-->0 observations (lambda=2.6 mm) of 10 polar-ringgalaxies, chosen from the Polar Ring Catalogue; we infer masses of H_2ranging from 7x10^7 to 2x10^10 Msolar, with an average of about 1x10^9Msolar. These H_2 masses are greater than the average molecular mass ofan early-type galaxy; we previously found similar results for a sampleof minor-axis dust-lane ellipticals. In the cases where we can estimatethe gas mass in the polar ring, including the H i masses fromliterature, they are high enough to allow self-gravitation to stabilizethe rings. This means that the ages of the rings may be >=1 Gyr.Indeed, the gas masses are often greater than those of most dwarfgalaxies: this would make it unlikely that the polar rings result fromthe recent accretion of a single gas-rich dwarf. A survey of the fieldsaround our sample galaxies shows in all but one case the presence of atleast one companion with either a similar redshift or similar bluemagnitude; these companions are close enough to have encountered thepolar-ring galaxy in <1 Gyr. The companion galaxies may be the sourceof the detected gas, through tidal stripping.
|An HI survey of polar ring galaxies. II. The Effelsberg sample.|
We present the results of a neutral hydrogen survey conducted with the100-m radiotelescope at Effelsberg of 44 northern objects in thepolar-ring galaxy atlas of Whitmore et al. (1990AJ....100.1489W). Theseobservations were performed to complement the Green Bank observations ofpolar-ring galaxies (Paper I, 1994AJ....107...99R). We detected 29 ofthese above our detection limit of a few mJy. The relative content ofneutral hydrogen (M_HI_/L_B_) of the early-type galaxies (E, S0) in thissample is significantly higher than for galaxies of the samemorphological types from comparison samples, i.e. for ellipticalgalaxies M_HI_/L_B_=0.17+/-0.09 and for S0 galaxiesM_HI_/L_B_=0.75+/-0.13 which is about 6 times the mean value from thecomparison samples for the same morphological types.
|An image database. II. Catalogue between δ=-30deg and δ=70deg.|
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
|A ^12^CO(1-0) survey of spiral galaxies in the region of the Coma supercluster.|
We present observations of the ^12^CO(J=1-0) line at 2.6mm of 65galaxies located in the Coma supercluster region: 33 actually belong tothe Coma supercluster while 32 are either foreground or backgroundobjects. These data have been obtained using the NRAO 12m telescope atKitt Peak (United States), and for four galaxies, using the IRAM 30mtelescope at Pico Veleta (Spain). Out of these 65 galaxies, 54 had neverbeen observed in the CO(1-0) line; 49 have been detected by us, of which37 are new detections. We give molecular gas masses deduced from the COline integrated intensities, and upper limits for the 16 undetectedobjects, computed with a Galactic conversion factorN(H_2_)=2.3x10^20^I(CO) and H_0_=75km/s/Mpc.
|A neutral hydrogen survey of polar-ring galaxies, 1: Green Bank observations of the northern sample|
We present the results of a neutral hydrogen survey conducted with theGreen Bank 140 foot radio telescope of 47 northern objects in thepolar-ring galaxy atlas of Whitmore et al. (1990). We detected 39 ofthese above our detection limit of 1.7 Jy km/s; the average measuredflux of 21 Jy km/s corresponds to an average neutral hydrogen mass of5.3 x 109 solar mass for a Hubble constant ofHzero = 75 km/s/Mpc. For the polar-ring galaxies in oursample that have also been observed with radio arrays, we find that the21 full width at half maximum (FWHM) Green Bank beam often includes muchmore flux than found by the synthesis instruments for the polar ringsalone; some of these galaxies are known to have gas-rich companions. Wecompare the neutral hydrogen content of the sample to the blueluminosity and Infrared Astronomical Satellite (IRAS) fluxes. The HI-mass-to-blue-light ratios of the confirmed and probable polar ringsare around unity in solar units, indicating that polar-ring galaxies (ortheir environments) are as gas-rich as typical irregular galaxies. Fortheir blue luminosity, the confirmed polar rings are underluminous inthe far infrared, as compared with the rest of the sample. They are alsofar infrared (FIR) underluminous for their H I masses, which suggeststhat most of the gas in the ring may be in stable orbits, rather thanflowing inward to trigger star formation in the central galaxy. The moredisordered class of 'related objects,' which includes a number ofobvious mergers, is highly luminous in the far infrared. Detailed notesfor each galaxy, including information about companions within the GB140 min beam that may contribute to the total H I line integral and itswidth, are contained in the Appendix.
|New observations and a photographic atlas of polar-ring galaxies|
A photographic atlas of polar-ring galaxies and related objects ispresented. The atlas includes kinematically confirmed polar-ringgalaxies (category A), good condidates based on their morphologicalappearance (category B), possible candidates (category C), and possiblyrelated objects (category D). New photometric and kinematic observationsare reported for several galaxies in the catalog, including observationsthat show that UGC 7576 and UGC 9796 ( = II ZW 73) are S0 galaxies withpolar rings. Roughly 0.5 percent of all nearby S0 galaxies appear tohave polar rings. When corrected for various selection effects (e.g.,nonoptimal viewing orientation, possible dimming, or limited lifetime ofthe ring) the percentage increases to about 5 percent of S0 galaxieswhich have, or have had a polar ring.
|Extragalactic dust. II - Far-infrared properties of early-type galaxies with dust lanes|
The far-infrared emission from some early-type galaxies with dust lanesindicates that star formation is taking place there. The ultravioletradiation from newly formed stars heats the dust to temperatures higherthan expected for H I regions illuminated by the integrated flux of theentire galaxy. Parallels with polar ring galaxies are drawn and anevolutionary scheme from dark lane to polar ring galaxy is suggested.
|A redshift survey of low-surface-brightness galaxies. I - The basic data|
Initial results from a 21 cm redshift survey of 375 very low surfacebrightness galaxies contained in the Uppsala General Catalog of Galaxiesare presented. The selection criteria and detection statistics as afunction of the sample optical properties are fully discussed. Theredshift distribution for the sample exhibits a pronounced peak at 5000km/s, corresponding to the well-studied Perseus-Pisces supercluster. Theoverall detection rate was 65 percent, and the bulk of the detectionsare genuine low surface brightness spiral galaxies, may with linewidthsin excess of 300 km/s, as opposed to true dwarf galaxies. It is arguedthat most of the nondetections are unlikely to be gas-poor dwarfs, butinstead are galaxies with velocities beyond 10,000 km/s. Taken as awhole, the sample demonstrates that optical surface brightness is notnecessarily a reliable indicator of intrinsic luminosity or mass.
|Colliding and merging galaxies. II - S0 galaxies with polar rings|
A detailed optical study of A0136-0801, a newly discovered spindlegalaxy, is presented, and the structure, origin, and evolution of ringedS0 galaxies in general are discussed. Photographic photometry andspectroscopy of the galaxy are described, and quantitative results arepresented for the galaxy's morphology and geometry, photometry of thespindle, brightness and H I content of the ring, rotation of spindle andring, and velocity dispersion of the spindle. The spindle is a normal S0disk seen nearly edge-on; the ring motions suggest that a massive haloextends far beyond the S0 disk and is more spherical than flat. From astudy of 22 related galaxies, it is found that a few percent of allfield S0's possess near-polar rings or disks. It is suggested that thesestructures are due to a second event, most likely the transfer of massfrom a companion galaxy during a close encounter and occasionally alsothe merger of a companion.
|Binary galaxie. I. A well-defined statistical sample.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1976ApJ...208...20T&db_key=AST
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