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|Early-Type Galaxies in Extremely Isolated Environments: Typical Ellipticals?|
We have conducted a BVR imaging survey of nine early-type galaxiespreviously verified to exist in extremely isolated environments. Ourgoals are to establish a baseline of morphological and photometricproperties for spheroidal systems evolving in extremely low-densityenvironments and to compare these properties with signatures predictedfor merged galaxy groups. We find that these isolated systems areunderluminous by at least a magnitude compared with objects identifiedas merged group remnants in other studies. Image processing techniquessensitive to shell features produced no detections, a result in strongcontrast to the high frequency of such structures found in otherisolated elliptical galaxies. Two objects, KIG 164 and KIG 870, appearto be merger remnants, as indicated by their disturbed morphology,apparent tidal features, and blue colors. KIG 164 exhibits an asymmetricnuclear morphology and a low surface brightness ``bridge'' between itand a possible dwarf satellite. KIG 870 shows both fan-shaped emissionat large radii and a possible double nucleus. Two other galaxies, KIG412 and KIG 792, are also blue, but without any morphologicalpeculiarities, suggesting that these systems are advanced mergers, olderthan KIG 164 and KIG 870. Two systems appear to be isolated lenticulargalaxies with no evidence of a merger history. Based on their redcolors, good fit to a R1/4-law light distribution, and thelack of morphological peculiarities, two other galaxies, KIG 557 and KIG824, are found to be excellent candidates for passively evolvingprimordial elliptical galaxies formed early in cosmic time. Optical datawere obtained with the 2.1 m Otto Struve telescope at McDonaldObservatory, which is operated by the University of Texas at Austin.
|The Bright SHARC Survey: The Cluster Catalog|
We present the Bright SHARC (Serendipitous High-Redshift Archival ROSATCluster) Survey, which is an objective search for serendipitouslydetected extended X-ray sources in 460 deep ROSAT PSPC pointings. TheBright SHARC Survey covers an area of 178.6 deg2 and hasyielded 374 extended sources. We discuss the X-ray data reduction, thecandidate selection and present results from our on-going opticalfollow-up campaign. The optical follow-up concentrates on the brightest94 of the 374 extended sources and is now 97% complete. We haveidentified 37 clusters of galaxies, for which we present redshifts andluminosities. The clusters span a redshift range of 0.0696
|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.
|Variable stars in open clusters.|
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