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Variable Stars in the Large Magellanic Cloud Globular Cluster NGC 2257. I. Results Based on 2007-2008 B, V Photometry
Nemec, James M.; Walker, Alistair; Jeon, Young-Beom
The variable stars in the Large Magellanic Cloud star cluster NGC 2257 are reinvestigated using photometry (to ~20th mag) of over 400 new B, V CCD images taken with the CTIO 0.9 m telescope on 14 nights in 2007 December and 2008 January. New period searches have been made using two independent algorithms (CLEAN, Period04); the resultant periods of…
Tangential Motions and Spectroscopy Within NGC 6720, the Ring Nebula
O'Dell, C. R.; Henney, W. J.; Sabbadin, F.
We have combined recent Hubble Space Telescope/WFPC2 images in the [O III] 5007 Å and [N II] 6583 Å lines with similar images made 9.557 years earlier to determine the motion of the Ring Nebula within the plane of the sky. Scaled ratio images argue for homologous expansion, that is, larger velocities scale with increasing distance from the central…
Further Definition of the Mass-Metallicity Relation in Globular Cluster Systems Around Brightest Cluster Galaxies
Whitmore, Bradley C.; Rothberg, Barry; Harris, William E. +2 more
We combine the globular cluster (GC) data for 15 brightest cluster galaxies and use this material to trace the mass-metallicity relations (MMRs) in their globular cluster systems (GCSs). This work extends previous studies which correlate the properties of the MMR with those of the host galaxy. Our combined data sets show a mean trend for the metal…
An HST/WFPC Survey of Bright Young Clusters in M31. II. Photometry of Less Luminous Clusters in the Fields
Barmby, P.; Bellazzini, M.; Perina, S. +5 more
We report on the properties of 89 low-mass star clusters located in the vicinity of luminous young clusters ("blue globulars") in the disk of M31. Eighty-two of the clusters are newly detected. We have determined their integrated magnitudes and colors, based on a series of Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 exposures in blu…
Multiwavelength Study of the Bright X-Ray Source Population in the Interacting Galaxies NGC 5774/NGC 5775
Gandhi, Poshak; Ghosh, Kajal K.; Gutiérrez, Carlos M. +3 more
A few nearby interacting galaxies are known that host elevated numbers of ultraluminous X-ray sources. Here we report the results of a multiwavelength study of the X-ray source population in the field of the interacting pair of galaxies NGC 5774/5775. A total of 49 discrete sources are detected, including 12 ultraluminous X-ray source candidates w…
The Frequency of Warm Debris Disks and Transition Disks in a Complete Sample of Intermediate-Mass Glimpse Stars: Placing Constraints on Disk Lifetimes
Kobulnicky, H. A.; Uzpen, B.; Kinemuchi, K.
The incidence of dusty debris disks around low- and intermediate-mass stars has been investigated numerous times in order to understand the early stages of planet formation. Most notably, the Infrared Astronomical Satellite (IRAS) mission observed the entire sky at mid- and far-infrared (IR) wavelengths, identifying the first debris disk systems, …
X-Ray Absorption and Optical Extinction in the Partially Obscured Seyfert Nucleus in Mrk 1393
Grupe, D.; Wang, T. G.; Yuan, W. +3 more
We present a detailed study of the X-ray and optical spectra of the luminous Seyfert galaxy Mrk 1393, which revealed variable partial obscuration of the active nucleus. The X-ray spectra obtained by XMM-Newton and Swift show moderate absorption with a column density around 3 × 1021 cm-2, consistent with a dust-reddening inter…
Characterization of Active Galactic Nuclei and Their Hosts in the Extended Groth Strip: A Multiwavelength Analysis
Pérez-González, P. G.; Ramos Almeida, C.; Gallego, J. +2 more
We have employed a reliable technique of classification of active galactic nuclei (AGNs) based on the fit of well sampled spectral energy distributions (SEDs) with a complete set of AGN and starburst galaxy templates. We have compiled UV, optical, and IR data for a sample of 116 AGNs originally selected for their X-ray and mid-IR emissions (96 wit…
Spatially Resolved Stellar Populations of Eight Goods-South Active Galactic Nuclei at z ~ 1
Koo, David C.; Ammons, S. Mark; Melbourne, Jason +2 more
We present a pilot study of the stellar populations of eight active galactic nucleus (AGN) hosts at z ~ 1 and compare with (1) lower redshift samples and (2) a sample of nonactive galaxies of similar redshift. We utilize K' images in the Great Observatories Origins Deep Survey South field obtained with the laser guide star adaptive optics system a…
Mapping the Spatial Distribution of Dust Extinction in NGC 959 Using Broadband Visible and Mid-Infrared Filters
Jansen, R. A.; Windhorst, R. A.; Tamura, K.
We present a method to estimate and map the two-dimensional distribution of dust extinction in the late-type spiral galaxy NGC 959 from the theoretical and observed flux ratio of optical V and mid-IR (MIR) 3.6 µm images. Our method is applicable to both young and old stellar populations for a range of metallicities, and is not restricted to …