Using data from NASA’s Fermi gamma ray space telescope,
astronomers have found an unusually massive gamma-ray pulsar with a
light-weight companion in orbit around it. This heavyweight pulsar is
identified as PSR J1311-3430 and it is estimated to weigh no less than twice
the mass of our Sun. A pulsar, also known as a pulsating neutron star, is an
extraordinarily dense remnant of what was once the core of a massive star. PSR
J1311-3430 packs over twice the mass of our Sun in a volume of space measuring
just a few kilometres across. A teaspoon of its material would contain a mass
amounting to billions of metric tons.
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Artist’s impression of a neutron star. Credit: Vadym
Sklyaruk
PSR J1311-3430 emits prodigious amounts of gamma-rays and
spins at a rate of 390 times per second. Its light-weight companion is a compact
object with at least 8 times the mass of Jupiter and is comprised mainly of
helium. The companion is believed to be the compact remnant of a star that was
cannibalized by the pulsar. Being at a distance of only 1.4 times the
Earth-Moon separation distance from the pulsar, the companion whizzes around
the pulsar once every 93 minutes. In fact, the companion swings around the
pulsar at a terrific speed of 2.8 million km/h.
At such a close proximity to the energetic pulsar, the
companion is being blasted at point-blank range by intense gamma radiation and
is literally evaporating away. One can imagine the “dayside” of the companion
being superheated until it shines blue-white. The cloud of vaporized material emanating
from the companion absorbs so much radio wave emissions from the pulsar that
the pulsar is invisible to radio telescopes. PSR J1311-3430 is a type of pulsar
known as a “black widow,” because like the black widow spider, which kills its
partner after mating, the pulsar is expected to eventually vaporize its
companion completely.
Reference:
Romani et al. (2013), “PSR J1311-3430: A Heavyweight Neutron
Star with a Flyweight Helium Companion”, arXiv:1210.6884 [astro-ph.HE]