NASA Astronomy Picture of the Day Collection

X-ray Moon and X-ray Star

An X-ray star winks out behind the Moon in these before and after views of a lunar occultation [ http://www.sky.net/…] of the galactic X-ray source designated GX5-1 [ http://heasarc.gsfc…]. The false color images were made using data from the ROSAT orbiting observatory [ http://heasarc.gsfc…] and show high energy X-rays in yellow (mostly from GX5-1), and lower energy X-rays in red (the Moon reflecting X-rays from the Sun [ http://antwrp.gsfc.…]). GX5-1 is a binary system [ http://heasarc.gsfc…] consisting of a neutron star [ http://antwrp.gsfc.…] and a companion star in mutual orbit about the system's center of mass. The gas in the companion star's outer envelope falls toward the neutron star and accumulates in a disk [ http://antwrp.gsfc.…] around it. This disk material swirls deeper in to the neutron star's gravitational well [ http://antwrp.gsfc.…], and is finally dumped onto its surface - in the process creating tremendous temperatures and generating the high energy X-rays.

ROSAT [ http://www.rosat.mp…], MPE [ http://www.mpe-garc…], NASA [ http://www.nasa.gov/]

Goddard Space Flight Center (GSFC)

Washington, D.C.

Moon

Sun

ROSAT

moon

http://antwrp.gsfc.…

SPD-APOD-ap960227