star pdf file

the X-ray properties of the cluster itself and the remarkable star HD 5980. But the field contains additional objects of interest.
In total, 79 X-ray point sources were detected in the Chandra observation: this is more than five times the number of sources
detected by previous X-ray surveys. We investigate here their characteristics in detail. The sources possess rather high
hardness ratios, and their cumulative luminosity function is steeper than that for the rest of the SMC at higher .luminosities.
Their absorption columns suggest that most of the sources belong to NGC346. Using new UBV RI imaging with the ESO 2.2m
telescope, we also discovered possible counterparts for 36 of these X-ray sources and estimated a B spectral type for a large
number of these counterparts. This tends to suggest that most of the X-ray sources in the field are in fact X-ray binaries.
Finally, some objects show X-ray and/or optical variability, with a need for further monitoring.
Author
H Ii Regions; X Ray Astrophysics Facility; Star Clusters; Magellanic Clouds; Star Formation
20030023714 NASA Goddard Space Flight Center, Greenbelt, MD, USA
New Evidence For Proton Cyclotron Resonance In a Magnetar Strength Field From SGR 1806-20
Parke, William; Ibrahim, Alaa I.; Swank, Jean H.; [2002]; 5 pp.; In English
Contract(s)/Grant(s): NAG5-11951; Copyright; Avail: CASI; A02, Hardcopy
A great deal of evidence has recently been gathered in favor of the picture that Soft Gamma Repeaters and Anomalous
X-Ray Pulsars are powered by ultra-strong magnetic fields (B greater than 10(exp 14) G; i.e. magnetars). Nevertheless, present
determination of the magnetic field in such magnetar candidates has been indirect and model dependent. A key prediction
concerning magnetars is the detection of ion cyclotron resonance features, which would offer a decisive diagnostic of the field
strength. Here we present the detection of a 5 keV absorption feature in a variety of bursts from the Soft Gamma Repeater
SGR 1806-20, confirming our initial discovery and establishing the presence of the feature in the source’s burst spectra. The
line feature is well explained as proton cyclotron resonance in an ultra-strong magnetic field, offering a direct measurement
of SGR 1806-20’s magnetic field (B approx. 10(exp 15) G) and a clear evidence of a magnetar. Together with the source’s
spin-down rate, the feature also provides the first measurement of the gravitational redshift, mass and radius of a magnetar.
Author
Proton Resonance; Cyclotron Resonance; Magnetars; Magnetic Fields
20030025228 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Are CME ‘interactions’ Really Important for Accelerating Major Solar Energetic Particle Events?
Richardson, I. G.; Lawrence, G. R.; Haggerty, D. K.; Kucera, T.; Szabo, A.; [2002]; ISSN 0094-8276; 5 pp.; In English;
Copyright; Avail: CASI; A01, Hardcopy
Recent studies have proposed that the presence or absence of an interaction with a preceding coronal mass ejection (CME)
or other coronal structure within approximately 50R(sub s), of the Sun discriminates large, fast CMEs associated with major
solar energetic particle (SEP) events from those that are not. We conclude that there is no compelling evidence that, if such
interactions take place, they play an important role in SEP acceleration. Reasons include: The reported statistical results are
consistent with a chance association between interacting CMEs and SEP events; Energetic SEPs are detected at Earth typically
before or around the time when the primary CME enters the LASCO C2 field of view - interactions higher in the corona cannot
play a role in acceleration of these particles; For approximately 60\% of major SEP events in 1997-2001, the preceding CME
fades into the background corona or is relatively narrow (less than 40 deg), suggesting any interaction will be weak; Radio
signatures attributed to CME interaction occur after SEP acceleration has commenced.
Author
Solar Flares; Coronal Mass Ejection; Solar Corpuscular Radiation; Energetic Particles; Infrared Signatures; Radio
Astronomy; Solar Corona
20030025241 Johns Hopkins Univ., Baltimore, MD, USA
A Detailed Study of Two Optically-Selected, High-Redshift Clusters of Galaxies
Lubin, Lori M.; [2002]; 1 pp.; In English
Contract(s)/Grant(s): NAG5-10511; No Copyright; Avail: CASI; A01, Hardcopy
We are obtaining detailed X-ray spectral and structural data for two distant, optically-selected clusters of galaxies which
are known X-ray emitters, CL1324+3011 at z=0.76 and CL1604+4304 at z=0.90. These observations will allow us to place
accurate constraints on the temperature, surface-brightness profile, and mass fraction of the intracluster medium in rich,
optically-selected clusters at very high redshift. The two target clusters are the most well-studied systems at z greater than 0.7
in the optical and infrared regimes; therefore, with the addition of the XMM data, we plan to study the specifics of the
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