The Planet, the White Dwarf, and the Neutron Star
A planet,
a white dwarf, and
a neutron star
orbit each other in
the giant globular star
cluster M4,
some 5,600 light-years away.
The most visible member of the
trio is the white dwarf star, indicated above in an
image
from the Hubble Space Telescope,
while the neutron star is detected at radio frequencies as
a pulsar.
A third body was known to be present in the pulsar/white
dwarf system and a detailed analysis of the
Hubble
data has indicated it is
indeed a planet
with about 2.5 times the mass of Jupiter.
In such a system, the planet is likely to be
about 13 billion years old.
Compared to our solar system's tender 4.5 billion years
and other
identified
planets of nearby stars,
this truly ancient world is by far the oldest planet known,
almost as old as the Universe itself.
Its discovery as part of an evolved cosmic trio suggests that
planet formation spans the age of the Universe and that
this newly discovered planet is likely only one of many formed
in the crowded environs
of globular star clusters.