National Aeronautics and Space Administration

The All-Sky Monitor (ASM) Movie - January 2000

The All-Sky Monitor Team from MIT have taken the All-Sky Monitor Light Curves and created an animated movie from them, demonstrating the dynamic nature of the X-ray sky in a striking visual format.

The amination displays the entire sky (above) and the central part of our Milky Way Galaxy (below). Each "frame" of the Quick-Time movie displays the X-ray sky at twelve hour intervals, at a rate of 4 days per second. A circle is plotted for each X-ray source observed by the All-Sky Monitor. The area of the circle is proportional to the intensity of the source. The color of the circle is indicative of the ratio of hard photons to soft photons: blue indicates higher temperatures and red cooler.

The track of the sun through the sky is shown, but its X-ray brightness is not shown. The brightest X-ray star (above center) is Scorpius X-1.

The most prominent objects shown are binary stellar systems containing a normal gaseous star and a black hole or neutron star. The latter two are called ``compact stellar objects''. The X-rays arise from gas being accreted from the normal gaseous star to the compact object. The gases gain great energy during their infall in the extremely strong gravity, becoming very hot (10 to 100 million degrees), and hence they emit copiously in X-rays rather than in normal light like our sun.

Other objects shown include supernove remnants and the active central regions of galaxies outside our Milky-Way system, known as Active Galactic Nuclei. The latter are believed to be massive black holes with masses millions of times more than the Sun.

The following three frames illustrate the content of the ASM Movie.

For more information, see http://space.mit.edu/XTE/movie/.