Recent Science Highlights
15 October 1994
- The detection of an ancient (5 billion years old) milli-second pulsar
with the Deep Survey Telescope during Guest Observer observations.
Because old neutron stars are expected to have cooled to non-EUVE
emitting temperatures, detection of this one indicates that highly
energetic re-heating has taken place. These observations are used to
discriminate between a diverse array of standard and exotic re-heating
mechanisms, and also to elucidate the ionization state of the
interstellar medium along the path to the star (Edelstein, et al.).
- The light curve of the intermediate polar cataclysmic variable EX Hya
shows clear evidence for eclipses by the secondary star and also by the
accretion stream. There is modulation at the white dwarf rotation
period. Most of the EUV flux probably arises in the "accretion curtain"
or region between the innermost radius of the accretion disk and the
white dwarf itself, where material begins to follow the magnetic field
lines rather than rotate in Keplerian fashion (Hurwitz, et al.).
- The paper "A Spectroscopic Measurement of the Coronal Density of Procyon"
by Schmitt, Haisch, and Drake has just come out as a report to the
journal Science (Vol. 265, pp. 1420-22). The main result is that using
the ratio of two Fe XIV lines at 211.32 and 264.79 Å, the authors
determined a density of 4-7 E+09 electrons/cm^3 -- a factor of 2-3 higher
that in typical solar active regions. This is the first direct
measurement of the coronal density in another solar-like star. From
this value the authors estimated that about 6% of the stellar surface
is covered by about 7E+04 loops.
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