Is RX J1856.5-3754 an old neutron star?
S. Campana 1, 2,
S. Mereghetti 3 and
L. Sidoli 3
Received 4 July 1996 / Accepted 30 September 1996
An unusual X-ray source, RX J1856.5-3754, has recently been discovered with ROSAT: its spectrum resembles that of supersoft sources, but the very high X-ray to optical flux ratio excludes the presence of a companion star, pointing to an isolated compact object. It has been proposed that RX J1856.5-3754 is an old, isolated neutron star accreting from the interstellar medium. Here we present a reanalysis of the ROSAT data. The HRI observation reveals an attitude reconstruction problem, resulting in a larger error box than previously reported. Deeper optical observations allow us to reveal a few optical counterparts inside the new error box, but the X-ray to optical flux ratio is still very high () and none of the candidates has peculiar colors.
Key words: stars: individual: RX J1856.5-3754 accretion X-rays: stars stars: neutron
© European Southern Observatory (ESO) 1997
Online publication: June 30, 1998