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.