Search Publications
Physical Properties of a 2003 April Quiescent Streamer
Raymond, J. C.; Uzzo, M.; Ko, Y. -K. +2 more
In 2003 April, the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO) observed a quiescent streamer in an effort to derive the physical plasma parameters across the streamer and as a function of height (from 1.75 to 5.0 Rsolar). Values for the electron temperature, proton and O5+
The Unusual Spectrum of the Ultraluminous X-Ray Source M82 X-1
Misra, R.; Agrawal, V. K.
The results of a spectral analysis, using XMM-Newton and Chandra data of the brightest ultraluminous X-ray source in the nearby galaxy M82, are presented. The spectrum of M82 X-1 was found to be unusually hard (photon spectral index Γ~1) with a sharp cutoff at ~6 keV. The disk blackbody emission model requires a nonphysically high temperature. Ins…
Iron in Hot DA White Dwarfs
Vennes, Stéphane; Lanz, Thierry; Chayer, Pierre +1 more
We present a study of the iron abundance pattern in hot, hydrogen-rich (DA) white dwarfs. The study is based on new and archival far-ultraviolet spectroscopy of a sample of white dwarfs in the temperature range 30,000 K<~Teff<~64,000 K. The spectra obtained with the Far Ultraviolet Spectroscopic Explorer, along with spectra obtain…
A Search for Early Optical Emission at Gamma-Ray Burst Locations by the Solar Mass Ejection Imager (SMEI)
Band, David L.; Jackson, Bernard V.; Buffington, Andrew +2 more
The Solar Mass Ejection Imager (SMEI) views nearly every point on the sky once every 102 minutes and can detect point sources as faint as R~10 mag. Therefore, SMEI can detect or provide upper limits for the optical afterglow from gamma-ray bursts in the tens of minutes after the burst, when different shocked regions may emit optically. Here we pro…
X-Ray Emission from the Double Neutron Star Binary B1534+12: Powered by the Pulsar Wind?
Garmire, G. P.; Pavlov, G. G.; Kargaltsev, O.
We report the detection of the double neutron star binary (DNSB) B1534+12 (=J1537+1155) with the Chandra X-Ray Observatory. This DNSB (Porb=10.1 hr) consists of the millisecond (recycled) pulsar J1537+1155A (PA=37.9 ms) and a neutron star not detected in the radio. After the remarkable double pulsar binary J0737-3039, it is t…
The Low-Mass Initial Mass Function of the Field Population in the Large Magellanic Cloud with Hubble Space Telescope WFPC2 Observations
Henning, Th.; Brandner, W.; Gouliermis, D.
We present V- and I-equivalent HST WFPC2 stellar photometry of an area in the Large Magellanic Cloud (LMC), located to the west of the bar of the galaxy, which accounts for the general background field of its inner disk. The WFPC2 observations reach magnitudes as faint as V=25 mag, and the large sample of more than 80,000 stars allows us to determ…
Three Gravitational Lenses for the Price of One: Enhanced Strong Lensing through Galaxy Clustering
McKean, J. P.; Treu, T.; Blandford, R. D. +7 more
We report the serendipitous discovery of two strong gravitational lens candidates (ACS J160919+6532 and ACS J160910+6532) in deep images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, each less than 40" from the previously known gravitational lens system CLASS B1608+656. The redshifts of both lens galaxies have been m…
Three-dimensional Structure of the 2002 April 21 Coronal Mass Ejection
Raymond, J. C.; Ko, Y. -K.; Lee, J. -Y. +1 more
A three-dimensional reconstruction of the 2002 April 21 partial halo Coronal Mass Ejection (CME) has been made based on the O VI 1032 Å and [Fe XVIII] 974 Å lines observed by the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO). We use the Doppler velocities to derive the CME structure along the li…
Ultraviolet Observations of Prominence Activation and Cool Loop Dynamics
Landi, E.; Kucera, T. A.
In this paper we investigate the thermal and dynamic properties of dynamic structures in and around a prominence channel observed on the limb on 2003 April 17. Observations were taken with the Solar and Heliospheric Observatory's Solar Ultraviolet Measurements of Emitted Radiation (SOHO SUMER) in lines formed at temperatures from 80,000 K to 1.6 M…
Line Shape Changes and Doppler Measurements in Solar Active Regions. I. A Method for Correcting Dopplergrams from SOHO MDI
Schou, J.; Wachter, R.; Sankarasubramanian, K.
We present a method to correct MDI high-resolution Dopplergrams in active regions for systematic observational errors due to the spectral line shape changes. We use a measurement campaign with the Advanced Stokes Polarimeter to investigate the influence of line shape changes in active regions on MDI Dopplergram calibration. An estimate of the widt…