A quark-nova is the
hypothetical
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obser ...
violent explosion resulting from the conversion of a
neutron star
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. w ...
to a
quark star
A quark star is a hypothetical type of compact, exotic star, where extremely high core temperature and pressure has forced nuclear particles to form quark matter, a continuous state of matter consisting of free quarks.
Background
Some massive ...
. Analogous to a
supernova heralding the birth of a neutron star, a quark nova signals the creation of a quark star. The term quark-novae was coined in 2002 by Dr. Rachid Ouyed (currently at the
University of Calgary
The University of Calgary (U of C or UCalgary) is a public research university located in Calgary, Alberta, Canada. The University of Calgary started in 1944 as the Calgary branch of the University of Alberta, founded in 1908, prior to being ins ...
, Canada) and Drs. J. Dey and M. Dey (Calcutta University, India).
The nova process
When a neutron star spins down, it may convert to a quark star through a process known as
quark deconfinement. The resultant star would have
quark matter
Quark matter or QCD matter (quantum chromodynamic) refers to any of a number of hypothetical phases of matter whose degrees of freedom include quarks and gluons, of which the prominent example is quark-gluon plasma. Several series of conferences ...
in its interior. The process would release immense amounts of energy, perhaps explaining the most energetic explosions in the universe; calculations have estimated that as much as 10
46 J could be released from the phase transition inside a neutron star. Quark-novae may be one cause of
gamma ray bursts
In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten milli ...
. According to Jaikumar ''et al.'', they may also be involved in producing heavy elements such as
platinum
Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish , a diminutive of "silver".
Pla ...
through
r-process nucleosynthesis.
Candidates
Rapidly spinning neutron stars with masses between 1.5 and 1.8
solar masses are theoretically the best candidates for conversion due to spin down of the star within a
Hubble time
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving ...
. This amounts to a small fraction of the projected neutron star population. A conservative estimate based on this, indicates that up to two quark-novae may occur in the
observable universe
The observable universe is a ball-shaped region of the universe comprising all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time, because the electromagnetic radiation from these ob ...
each day.
Theoretically, quark stars would be radio-quiet, so
radio-quiet neutron stars may be quark stars.
Observations
Direct evidence for quark-novae is scant; however, recent observations of supernovae
SN 2006gy,
SN 2005gj and
SN 2005ap may point to their existence.
See also
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References
External links
Quark-novae produce neutrino bursts, which can be detected by neutrino observatories
(SpaceDaily) June 7, 2006
Quark Nova Project animations
(University of Calgary)
{{DEFAULTSORT:Quark-Nova
Quark stars
Supernovae
Hypothetical astronomical objects