Search Publications
Lifting the Iron Curtain: Toward an Understanding of the Iron Stars XX Oph and AS 325
Howell, Steve B.; Cool, Richard J.; Peña, Maria +2 more
We present new optical, near-infrared, and archival ultraviolet observations of XX Ophiuchi and AS 325, two proposed ``iron'' stars. These unusual stars have optical spectra dominated by emission lines arising from hydrogen, as well as ionized metals such as iron, chromium, and titanium. Both stars have been classified as ``iron'' stars, and a num…
Magnetic White Dwarfs in the Two Micron All Sky Survey: A Search for Candidate Binary Systems
Hoard, D. W.; Wachter, Stefanie; Howell, S. B. +2 more
Our understanding of the formation and evolution of magnetic cataclysmic variables from initially detached, post-common-envelope binary stars containing a magnetic white dwarf and a main-sequence star is currently poorly constrained, due to the lack of observational identification of the progenitor systems. Very few potential pre-cataclysmic varia…
Characterizing the Adaptive Optics Off-Axis Point-Spread Function. II. Methods for Use in Laser Guide Star Observations
Faber, S. M.; Gates, E. L.; Macintosh, B. A. +2 more
Most current astronomical adaptive optics (AO) systems rely on the availability of a bright star to measure the distortion of the incoming wave front. Replacing the guide star with an artificial laser beacon alleviates this dependency on bright stars and therefore increases sky coverage, but it does not eliminate another serious problem for AO obs…
A Far-Ultraviolet Study of the Old Nova V841 Ophiuchi
Sion, Edward M.; Engle, Scott G.
We have carried out a synthetic spectral analysis of archival International Ultraviolet Explorer spectra of the old nova V841 Oph (Nova Oph 1848) taken 15 years apart. The spectra reveal a rising continuum shortward of 1560 Å, a C IV P Cygni profile indicative of wind outflow associated with disk accretion in one spectrum, a deep Lyα profile, and …
uvby FCAPT Photometry of the Magnetic Chemically Peculiar Stars 36 Aurigae, HR 2722, 13 Andromedae, and HD 220147
Adelman, Saul J.
Differential Strömgren uvby observations obtained with the Four College Automated Photoelectric Telescope (FCAPT) are presented for the magnetic chemically peculiar (mCP) stars 36 Aur, HR 2722, 13 And, and HD 220147. The new data help to better define the light curves. The period for 36 Aur was found to be 14.368 days, close to that for the previo…
Looking for Discrete UV Absorption Features in the Early-Type Eclipsing Binaries µ1 Scorpii and AO Cassiopeiae
Sahade, J.; Kondo, Y.; Arias, M. L. +1 more
A search for discrete absorption components in the ultraviolet spectra of the early-type binaries µ1 Scorpii and AO Cassiopeiae has been undertaken by analyzing material secured with the International Ultraviolet Explorer satellite during an exclusively assigned interval of nearly 50 hr. While the spectra of µ1 Sc…
A Star Catalog for the Open Cluster NGC 188
Stetson, Peter B.; VandenBerg, Don A.; McClure, Robert D.
We present new BVRI broadband photometry for the old open cluster NGC 188, based on an analysis of 299 CCD images either obtained by us, donated by colleagues, or retrieved from public archives. We compare our results on a star-by-star basis with data from 11 previous photometric data sets for the cluster. We homogenize and merge the data from all…
The Ultraviolet and Optical Spectra of Luminous B-Type Stars in the Small Magellanic Cloud
Lennon, D. J.; Evans, C. J.; Walborn, N. R. +2 more
We present ultraviolet spectra from the Space Telescope Imaging Spectrograph (STIS) of 12 early B-type stars in the Small Magellanic Cloud (SMC), composed of nine supergiants and three giants. A morphological comparison with Galactic analogs is made using archival data from the International Ultraviolet Explorer (IUE). In general, the intensity of…
New Light Curves and Orbital Solution for AM Leonis
Terrell, Dirk; Hiller, Mary E.; Osborn, Wayne
New UBVRI photometry has been obtained for the W UMa eclipsing system AM Leonis. The data have been used to derive nine times of minimum and to construct light curves. The minimum timings show that the system recently had a significant period increase. Modeling of the light curves shows AM Leo to be an overcontact system with a mass ratio of 2.51.…
Short-Period Variable Be Stars Discovered or Confirmed through Self-Correlation Analysis of Hipparcos Epoch Photometry
Percy, John R.; Harlow, Christopher D. W.; Wu, Alice P. S.
We have surveyed 277 bright Be stars for short-period (0.2-2 day) photometric variability using self-correlation analysis of Hipparcos epoch photometry. This extends the work of Percy et al.; the methods are as described there. We report the discovery, timescale, and amplitude of short-period variability in: HD 7636 (V764 Cas), HD 11606 (V777 Cas)…