Search Publications
The Stellar Content and Star Formation History of the Late-Type Spiral Galaxy NGC 300 from Hubble Space Telescope Observations
Brandner, W.; Martínez-Delgado, D.; Butler, D. J.
We present the first Hubble Space Telescope (HST) WFPC2 V and I photometry for the Sculptor Group galaxy NGC 300 in four fields ranging from the center to the outer edge. We have made the first measurement of the star formation histories in two disk fields: the oldest stars were born at similar epochs and formation activity increased but at differ…
Barnard's Star and the M Dwarf Temperature Scale
De Robertis, M. M.; Dawson, P. C.
The recently measured angular diameter of Barnard's star, together with its large and precise parallax, and a spectral energy distribution that extends from the near-ultraviolet to almost 12 µm establish some of the star's fundamental properties-we find a bolometric luminosity L=(3.46+/-0.17)×10-3Lsolar, radius R=0.200+…
GRB 021211 as a Faint Analog of GRB 990123: Exploring the Similarities and Differences in the Optical Afterglows
Bloom, J. S.; Caldwell, Nelson; Garnavich, Peter M. +7 more
We present BVRCJHKs photometry of the optical afterglow of the gamma-ray burst GRB 021211 taken at the Magellan, MMT, and WIYN observatories between 0.7 and 50 days after the burst. We find an intrinsic spectral slope at optical and near-infrared wavelengths of 0.69+/-0.14 at 0.87 days. The optical decay during the first day …
XMM-Newton Observations of the Extremely Low Accretion Rate Polars SDSS J155331.12+551614.5 and SDSS J132411.57+032050.5
Anderson, Scott F.; Brinkmann, J.; Szkody, Paula +6 more
XMM-Newton observations of the polar SDSS J155331.12+551614.5 reveal that all the X-ray flux emerges at energies less than 2 keV. The best fit to the spectrum is with a thermal plasma with kT=0.8 keV plus a 20-90 eV black body, yielding a thermal X-ray luminosity of (8.0-9.5)×1028 ergs s-1. The low temperature and X-ray lumin…
The Nature of SN 1961V
Chu, You-Hua; Gruendl, Robert A.; Stockdale, Christopher J. +3 more
The nature of SN 1961V has been uncertain. Its peculiar optical light curve and slow expansion velocity are similar to those of superoutbursts of luminous blue variables (LBVs), but its nonthermal radio spectral index and declining radio luminosity are consistent with decades-old supernovae (SNe). We have obtained Hubble Space Telescope STIS image…
A Hubble Space Telescope Study of Star Formation in the Inner Resonance Ring of NGC 3081
Byrd, Gene G.; Freeman, Tarsh; Buta, Ronald J.
We present Hubble Space Telescope Wide Field Planetary Camera 2 images of the inner regions of NGC 3081, an absolute magnitude MB=-20.0 early-type barred spiral having four well-defined resonance rings: a nuclear ring, an inner ring, an outer R1 ring, and an outer R'2 pseudoring. Here we focus on a photo…
A Preliminary Observational Search for Circumbinary Disks around Cataclysmic Variables
Howell, Steve B.; Holberg, J. B.; Belle, Kunegunda E. +2 more
Circumbinary (CB) disks have been proposed as a mechanism to extract orbital angular momentum from cataclysmic variables (CVs) during their evolution. As proposed by Taam & Spruit, these disks extend outward to several astronomical units and should be detected observationally via their infrared flux or by absorption lines in the ultraviolet sp…
Looking Closely at Medusa: Star-forming Knots at the Center of NGC 4194
Kaiser, M. E.; Weistrop, D.; Eggers, D. +3 more
We report high-resolution ultraviolet and visible-wavelength imaging of the blue compact galaxy NGC 4194 (the Medusa) using the Hubble Space Telescope. A complete sample of 38 UV-bright knots is identified. These knots produce 20% of the ultraviolet emission from the area of the galaxy observed. The bright end of the knot flux distribution can be …
Deep Photometry in a Remote M31 Major-Axis Field Near G1
Ho, Luis C.; Gebhardt, Karl; Rich, R. Michael +2 more
We present photometry from Hubble Space Telescope (HST) Wide Field Planetary Camera 2 parallel imagery of a remote M31 field at a projected distance of ~34 kpc from the nucleus near the southwest major axis. This field is near the globular cluster G1, and near one of the candidate tidal plumes identified in the survey of Ferguson et al. (2002). Th…
WIYN Open Cluster Study. XIX. Main-Sequence-Fitting Distances to Open Clusters Using V-K Color-Magnitude Diagrams
Sarajedini, Ata; Brandt, Ken; Grocholski, Aaron J. +1 more
We have combined existing optical magnitudes for stars in seven open clusters and 54 field stars with the corresponding JHKs photometry from the Two Micron All Sky Survey (2MASS). Combining optical with near-IR photometry broadens the color baseline, minimizing the influence of photometric errors and allowing better discrimination betwe…