SUMMARY OF PROPOSAL 42039
ASSOC. PROF. FREDERICK M. WALTER
STATE UNIVERSITY OF NEW YORK
NY USA 11794-2100
STONY BROOK
Z

  E-mail: FWALTER@ASTRO.SUNYSB.EDU	Tel: 516-632-8232	Fax: 516-632-8240
  Medium: 2GBDAT

Subject: STARS                                                       
  Title: THE X-RAY SPECTRUM OF AN ISOLATED OLD NEUTRON STAR                              


Abstract:
 RXJ185635-3754 is a bright soft source projected on the R CrA molecular cloud. It is
 a 57 eV black body at a distance <120pc, with an emitting area of 480 sq km. It is
 likely to be a isolated old neutron star. If it is magnetized, then theory predicts
 the existence of cyclotron line emission in the 6-15 keV regime. We propose an ASCA
 observation to search for this hard X-ray emission. Detection of the line provides
 confirmation that the source is an isolated neutron star accreting from the
 interstellar medium. Absence of a cyclotron line demonstrates that either the
 magnetic field is less than 10^12G or the star is not accreting. The SIS spectrum of
 the soft black body tail will be used to search for deviations from the pure black body predicted for accreting low luminosity neutron stars.

 Co-Is:
   1  JOHN WANG           	UNIV. OF MARYLAND             USA       
      (No Co-I contact data)
   2  STEVEN SKINNER      	JILA, U. COLORADO             USA       
   3  ROBERT NELSON       	CITA                          CANADA    


Target Name           PRI RA        Dec        Time TC  Off GIS SIS_Cts  Obs
-------------------   --- --------  --------   ---- --  --- --- -------  ---
RXJ185635-3754         0  284.1471  -37.9089    40   N   Y   P  0.07900   1