The small object XMMU J173203.3-344518 is indeed amazing, packing around
three-quarters of the mass of our Sun into a ball large enough to fit within
Manhattan. strange, even. Maybe strange.
Is it odd, though? According to a recent study by physicists at the Federal
University of ABC and the University of So Paulo in Brazil, this
mind-bogglingly dense ball of star material may be weird after all, but
perhaps not in the manner you might expect.
The distance between Earth and the small star-crasher
HESS J1731-347
was recalculated last year by scientists from the Institute for Astronomy
and Astrophysics at the University of Tübingen in Germany.
The updated closeness was just 8,150 light-years distant, which was less
than the earlier prediction of 10,000 light-years. Recalculating the compact
object's attributes, notably its size and mass, was necessary to account for
the new distance.
That's when things started to get a bit exciting.
A fraction of the stars' outer layers are blown away when stars of a
certain mass collapse in a cosmic thunderclap of heat and electromagnetic
when they run out of the sort of fuel that their gravity can conveniently
crush the daylights out of.
All that is left is a dense object whose atoms are packed close together.
Protons are forced to shed their charge and change into neutrons as a result
of electrons being packed into their nuclei deep into the object's core.
It's a baby neutron star; congrats.
If there is sufficient mass, all of the additional gravity overrides the
weak nuclear forces and causes the matter to collapse into an unfathomable
state, producing a black hole. But in what is known as a "white dwarf,"
there is not enough mass, and the atoms continue to coexist
peacefully.
Neutron stars are expected to have a lower mass limit of somewhat more than
one solar mass. Only 1.17 times the mass of the Sun has been found to be the
lightest object
so far.
XMMU J173203.3-344518 isn't only a record-breaker; it's also baffling at 77
percent of a solar mass. Neutron stars shouldn't be so small.
Which suggests that it might not even be a
neutron star.
The researchers speculated that it was instead a phenomenon known as a weird
star, which is mostly made up of particles called odd quarks. They left
their conclusions for other researchers to consider.
This inquiry picked up where the last study left off, returning to the
exceptionally small compact item within HESS J1731-347 and verifying its
mass, radius, and surface temperature.
The scientists concluded that this odd small item still had all of the
characteristics of a fictitious strange star after comparing their findings
with equations for strange matter and theoretical models for their formation
in supernovae.
Basic building blocks called quarks form trios to form baryons. The protons
and neutrons found in nuclear matter are two of these groupings' more
well-known representatives.
Those bundles of quarky deliciousness can defy the forces holding them
together to organize into something less structured if you focus enough
energy in any one place. If you apply enough pressure to this heated soup,
its quarks may emerge as an entirely new type of substance known as,
unsurprisingly, quark matter.
Quarks naturally exist in a wide range of shapes or tastes. Protons and
neutrons are created when the tastes of "up" and "down" combine. Down quarks
can change into up quarks under strong enough pressure, and up quarks can
then change into a strange quark, a different flavor.
Though some theories show quark matter often developed right from the start
of the collapse, it is still unclear exactly how a hyper compact entity
consisting primarily of weird quarks arises from a supernova.
Something allows this matter to predominate under quite unusual
circumstances, releasing more energy during the collapse to shake off more
mass than normal and leave that surplus of quarks behind.
Returning to the most recent research, its updated calculations of XMMU
J173203.3-344518's age and surface temperature, as well as the object's
radius and minuscule mass, are compatible with cooling circumstances that
suggest an odd composition.
That does not mean that a more "normal" explanation cannot exist. Given
that XMMU J173203.3-344518 is a landmark instance, this does provide the
astronomy community additional justification to point their telescopes in
its direction.
Despite the fact that this is a significant example and that other
detections could enhance the overall picture, the
authors contend
that it is premature to draw any firmer conclusions.
This research has been accepted in Astronomy and Astrophysics Letters
and is currently available on
arXiv.
