1,370 research outputs found
X-ray Variability and Period Determinations in the Eclipsing Polar DP Leo
An analysis of ROSAT observations for the eclipsing magnetic cataclysmic
binary DP Leo provides constraints on the origin, size, temperature,
variability and structure of the soft X-ray emission region on the surface of
the white dwarf. These data, when combined with prior observations, show a
progression of approximately 2 degrees per year in the impact position of the
accretion stream onto the white dwarf. One explanation for the observed drift
in stream position is that a magnetic activity cycle on the secondary produces
orbital period oscillations. These oscillations result in an orbital period
which cycles above and below the rotational period of the nearly synchronous
white dwarf. The accretion stream and X-ray emission regions are modeled to fit
the observational data. A distance to the system is also calculated. [An
erroneous value for the cyclotron luminosity, included in an earlier paper
version of the preprint, is corrected here.]Comment: uuencoded PostScript file (25 pages) + 8 figures available by
anonymous ftp to ftp.astro.psu.edu (in the directory /pub/robinson), to
appear in ApJ, PSU preprint 1994-1
Conceptual Frameworks as a Source of Cultural Distinctions
The purpose of this paper is to identify the conceptual frameworks of two distinct and unrelated peoples in order to show that the source of their particular views is a result of incommensurable conceptual frameworks. The peoples that I have chosen are the Native American, primarily the Athabascan (Apache, Navajo) with whom I am most familiar, and the group that the Native American calls the European -- those peoples that have the roots of their ancestry in the various nations of Europe
A search for X-ray pulsations from the galactic center
Data from the SAS-3 satellite were used in a search for X-ray pulsations from the direction of the galactic center. No periodic X-ray behavior was detected in the frequency interval 0.6 Hz to 0.0006 Hz and energy range 2.5 - 35 keV. For periods less than 60 sec, the upper limit to the amplitude of any pulsation in the 2.5 - 10 keV band is approximately .0017 cts/sq cm/s. This corresponds to a pulsed fraction of approximately 1.3 percent of the total GCX flux. Somewhat higher limits apply for longer periods and for energies greater than 10 keV
- …