Search Publications
HST Imaging of MEGA Microlensing Candidates in M31
Crotts, Arlin P. S.; Kuijken, Konrad; Widrow, Lawrence M. +5 more
We investigate HST/ACS and WFPC2 images at the positions of five candidate microlensing events from a large survey of variability in M31 (MEGA). Three closely match unresolved sources, and two produce only flux upper limits. All are confined to regions of the color-magnitude diagram where stellar variability is unlikely to be easily confused with …
Far-Ultraviolet and Optical Observations of BW Vulpeculae
Smith, Myron A.; Fullerton, Alex W.; Sterken, Christiaan
We have compared the behavior of 39 Far-Ultraviolet Spectroscopic Explorer spectra through the pulsation cycle of the very large amplitude β Cephei star BW Vul with optical and UV (IUE) spectra, as well as optical photometry. The FUSE light curve suggests a temperature amplitude of about 4000 K, while the radial velocity curve is similar to corres…
Stream-Field Interactions in the Magnetic Accretor AO Piscium
Hellier, Coel; van Zyl, Liza
UV spectra of the magnetic accretor AO Psc show absorption features for half the binary orbit. The absorption is unlike the wind-formed features often seen in similar stars. Instead, we attribute it to a fraction of the stream that overflows the impact with the accretion disk. Rapid velocity variations can be explained by changes in the trajectory…
A MERLIN Observation of PSR B1951+32 and Its Associated Plerion
Muxlow, T. W. B.; Golden, A.; Shearer, A. +4 more
In an investigative 16 hr L-band observation using the MERLIN radio interferometric array, we have resolved both the pulsar PSR B1951+32 and the structure within the flat spectral radio continuum region, believed to be the synchrotron nebula associated with the interaction of the pulsar and its ``host'' supernova remnant CTB 80. The extended struc…
Comparison of the Sacramento Peak Fe XIV Index with a Model Index Computed from Differential Emission Measure Maps
Newmark, J. S.; Cook, J. W.; Altrock, R. C.
We compare the Sacramento Peak Fe XIV 5303 Å green line index with a model index time series for the period of operations of the EUV Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO), covering the years 1996-2002, from cycle minimum past the peak of the current activity cycle 23. We compute a differential emission meas…
H1517+656: The Birth of a BL Lacertae Object?
Urry, C. Megan; O'Dowd, Matthew; Scarpa, Riccardo +2 more
H1517+656 is an unusual source, even for a BL Lac object. It is one of the most luminous BL Lac objects known, with extreme emission properties at radio, optical, and X-ray frequencies. Furthermore, in our WFPC2 snapshot survey we discovered a series of peculiar arcs describing a 2.4" radius ring surrounding the source. This paper describes follow…