Search Publications
Stellar Populations in the Outer Reaches of M31 and M32 from WFPC2 Photometry
Mateo, Mario; Alonso-García, Javier; Worthey, Guy +1 more
Hubble Space Telescope Wide Field Planetary Camera 2 photometry in a field 7 effective radii from the nucleus of M32 and a comparison field in the outer disk of M31, already examined for the presence of RR Lyrae variable stars, are further compared. No relative distance difference between the two fields could be measured using the luminosity of re…
Dwarf Novae with Newly Determined Parallaxes: Model Analyses of VY Aquarii, RU Pegasi, and T Leonis
Sion, E. M.; Hamilton, R. T.
Using newly determined parallaxes for dwarf novae, we have derived outburst accretion rates for VY Aqr, RU Peg, and T Leo, and for T Leo during quiescence. The two short-period dwarf novae, VY Aqr and T Leo, show good agreement with optically thick steady-state accretion disks in outburst, whereas RU Peg shows a significant departure from a steady…
A Far-Ultraviolet Spectroscopic Analysis of the Central Star of the Planetary Nebula Longmore 1
Bianchi, L.; Herald, J. E.
We have performed a non-LTE spectroscopic analysis using far-UV and UV data of the central star of the planetary nebula K1-26 (Longmore 1) and found Teff=120+/-10 kK, logg=6.7+0.3-0.7 cm s-2, and Y~=0.10. The temperature is significantly hotter than previous results based on optical line analyses, highli…
Newly Identified Star Clusters in NGC 6822, and the Age Distribution of Its Cluster System
Hodge, Paul; Krienke, Karl
From past ground-based imaging and our current Hubble Space Telescope images, we have identified 51 candidate open clusters in the dwarf irregular galaxy NGC 6822. Of these, 25 candidates are located on our HST images with standard wideband filters, 16 of which are securely identified as true clusters. Integrated photometry in B, V, and I for seve…
The Large Binocular Camera Image Simulator
Fontana, A.; Grazian, A.; Giallongo, E. +3 more
The Large Binocular Camera Image Simulator (LBCImSim) is a package for generating artificial images in the typical FITS format. It operates on real or artificial images, simulating the expected performances of real instruments by including several observing conditions (filters, air mass, flat field, and exposure time) and creating images with the …
Calibration of Hubble Space Telescope Advanced Camera for Surveys Emission-Line Filters
O'Dell, C. R.
The most commonly used narrowband filters of the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope do not allow the clear delineation of individual emission lines as done with the more narrow field-of-view Wide Field and Planetary Camera. However, we have determined the calibration characteristics that allow separation of the Hα and …
60 Milliarcsecond Near-Infrared Imaging of 3C 273 with Altair and Gemini
Hutchings, J. B.; Rigaut, F.; Veran, J. -P. +1 more
We report data from the commissioning run of the Altair adaptive optics instrument on Gemini North. The bright QSO 3C 273 was observed at f/32 in the H and J bands, and at f/14 with J band, using the QSO itself as guide star. Resolution of approximately 60 mas full width at half-maximum (FWHM) was achieved in H band. The data and point-spread func…
Clarification of the Nature of the Galaxy [CFC97] Cen 05
Da Costa, G. S.; Jerjen, H.; Bouchard, A.
The galaxy [CFC97] Cen 05 has in the past been considered an H I-rich dwarf galaxy in the nearby Centaurus A group. We have used Australia Telescope Compact Array observations to show that the H I associated with [CFC97] Cen 05 by Côté et al. is most likely a Galactic high-velocity cloud that is centered ~17' from the optical image of the galaxy. …
Far Ultraviolet Spectroscopic Explorer Spectroscopy of the Transitional Magnetic Cataclysmic Variable V405 Aurigae
Sing, David K.; Szkody, Paula; Howell, Steve B. +1 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the magnetic cataclysmic variable V405 Aurigae. Together with four other DQ Her-type binaries, V405 Aur forms a small subclass of intermediate polars that are likely to evolve into low magnetic field strength polars, similar to AM Her. Our co-added FUSE spectrum exhibits broa…
High Spatial Resolution Hubble Space Telescope NICMOS Observations of Markarian 231
Schneider, G.; Neugebauer, G.; Low, F. J.
Observations of Markarian 231 at 1.1 µm taken with NICMOS on the Hubble Space Telescope are described. The brightness of the object in the near-infrared, and the inherent short-term stability of the NICMOS optical and instrumental system, enables the application of special observational and analysis techniques that effectively increase high …