Unusual Flashes Toward Globular Cluster M22
Explanation:
What is causing the unusual flashes behind globular cluster M22?
This teaming ball of stars is the brightest
globular cluster
visible in Earth's northern hemisphere.
M22, shown in full in the inset, spans about 50
light years away and lies 8500 light-years toward the
constellation of
Sagittarius.
M22's center was
recently imaged repeatedly by the high resolution
Hubble Space Telescope.
Behind
M22 are many more stars near the
center of our Galaxy.
Unexpectedly, several stars
near the Galactic center
-- well behind
M22 -- appeared to nearly double in
brightness and return to normal within 20 hours.
One hypothesis posed to explain these quick brightness changes is the
gravitational lens effect
of large planets roaming freely in the cluster.
One problem with this is that there was no such
planetary population was previously known!
Future observations are planned to better
understand these mysterious flashes.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
