Search Publications
Probing the Nature of the G1 Clump Stellar Overdensity in the Outskirts of M31
Lewis, Geraint F.; Ibata, Rodrigo A.; Johnston, Kathryn V. +5 more
We present deep Hubble Space Telescope ACS observations of the G1 clump, a distinct stellar overdensity lying at ~30 kpc along the southwestern major axis of M31, close to the G1 globular cluster (from the work of Ferguson and coworkers). Our well-populated color-magnitude diagram reaches ~7 mag below the red giant branch tip with 90% completeness…
HD 97048's Circumstellar Environment as Revealed by a Hubble Space Telescope ACS Coronagraphic Study of Disk Candidate Stars
Kamp, I.; Meixner, M.; Ardila, D. R. +5 more
We present the results of a coronagraphic scattered-light imaging survey of six young disk candidate stars using the Hubble Space Telescope Advanced Camera for Surveys. The observations made use of the 1.8" occulting spot through the F606W (broad V) filter. Circumstellar material was imaged around HD 97048, a Herbig Ae/Be star located in the Chama…
Hubble Space Telescope NICMOS Observations of NGC 1333: The Ratio of Stars to Substellar Objects
Schneider, Glenn; Meyer, Michael R.; Greene, Thomas P. +4 more
We present an analysis of NICMOS photometry and low-resolution grism spectroscopy of low-mass stars and substellar objects in the young star-forming region NGC 1333. Our goal is to constrain the ratio of low-mass stars to substellar objects down to 20MJup in the cluster, as well as constrain the cluster initial mass function (IMF) down …
Mid-Infrared Photometry of Mass-losing Asymptotic Giant Branch Stars
Corcione, L.; Guandalini, R.; Busso, M. +2 more
We present ground-based mid-IR imaging for 27 M-, S-, and C-type asymptotic giant branch (AGB) stars. The data are compared with those of the database available thanks to the IRAS, Infrared Space Observatory, Midcourse Space Experiment, and Two Micron All Sky Survey catalogs. Our goal is to establish relations between the IR colors, the effective …
H-R Diagrams Based on the HD Stars in the Michigan Spectral Catalogue and the Hipparcos Catalog
Sowell, J. R.; Trippe, M.; Caballero-Nieves, S. M. +1 more
The systematic, spectroscopic two-dimensional classification of the HD stars by N. H. is approximately three-quarters complete. Over 161,000 stars have been classified visually using 10° objective-prism plates (2 Å resolution) taken at CTIO with the Michigan Curtis Schmidt telescope. The published portion of this large, homogeneous database, taken…
Cool Customers in the Stellar Graveyard. IV. Spitzer Search for Mid-IR excesses Around Five DAs
Debes, John H.; Sigurdsson, Steinn; Hansen, Brad
Hydrogen atmosphere white dwarfs with metal lines, so-called DAZs, require external accretion of material to explain the presence of weak metal-line absorption in their photospheres. The source of this material is currently unknown, but could come from the interstellar medium, unseen companions, or relic planetesimals from asteroid belt or Kuiper …
An Update on the X-Ray Transient Narrow-Line Seyfert 1 Galaxy WPVS 007: Swift Observations of UV Variability and Persistence of X-Ray Faintness
O'Brien, Paul T.; Schady, Patricia; Leighly, Karen M. +3 more
We report on the detection of UV variability and the persistence of X-ray faintness of the X-ray transient narrow-line Seyfert 1 galaxy WPVS 007 based on the first year of monitoring with Swift between 2005 October and 2007 January. WPVS 007 has been an unusual source. Although it was X-ray-bright in the ROSAT All-Sky Survey, it has been extremely…
A Study of Compact Radio Sources in Nearby Face-on Spiral Galaxies. II. Multiwavelength Analyses of Sources in M51
Schinnerer, E.; Kilgard, R. E.; Cowan, J. J. +2 more
We report the analysis of deep radio observations of the interacting galaxy system M51 from the Very Large Array, with the goal of understanding the nature of the population of compact radio sources in nearby spiral galaxies. We detect 107 compact radio sources, 64% of which have optical counterparts in a deep Hα Hubble Space Telescope image. Thir…
Newly Identified Star Clusters in M33. I. Integrated Photometry and Color-Magnitude Diagrams
Sarajedini, Ata; Schommer, Robert; Barker, M. K. +2 more
We present integrated photometry and color-magnitude diagrams (CMDs) for 24 star clusters in M33, of which 12 were previously uncataloged. These results are based on Advanced Camera for Surveys observations from the Hubble Space Telescope of two fields in M33. Our integrated V magnitudes and V-I colors for the previously identified objects are in …
Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images
Levay, Zoltan G.; English, Jayanne; Frattare, Lisa M. +2 more
The quality of modern astronomical data and the agility of current image-processing software enable the visualization of data in a way that exceeds the traditional definition of an astronomical image. Two developments in particular have led to a fundamental change in how astronomical images can be assembled. First, the availability of high-quality…