Particles called quarks hold the key to the final fate of some stars

Particles called quarks hold the key to the final fate of some stars

Subject: Science and tech

Sec: Space sector

Tags: Quarks , Neutron Star

What is Quark?

• Matter is made up of atoms, consisting of a nucleus with protons and neutrons, and electrons around it.
• Protons and neutrons are not fundamental particles but are composed of even smaller particles called quarks.
• Quarks are unique because they cannot exist alone but only in groups, known as hadrons, like protons and neutrons.
• Origin and naming:
  • The concept of quarks emerged in the 1960s when physicists, explaining why neutrons (neutral in charge) have a magnetic moment, hypothesized that neutrons are composed of smaller, charged particles (quarks) whose charges cancel out. This theory was confirmed in the 1970s.
  • Quarks, named by physicist Murray Gell-Mann from James Joyce’s “Finnegan’s Wake,” come in six “flavors,” including charm and strange, and have properties such as “color charge.”
• Properties:
  • Quarks, which come in six types (up, down, top, bottom, strange, and charm) and each bear one of three color charges, are fundamental components of matter.
  • Their antimatter counterparts are known as antiquarks.
  • Quark-antiquark pairs form mesons, while clusters of three quarks make up baryons, the constituents of normal matter.
  • Quarks are bound together by gluons through the strong nuclear force, described by quantum chromodynamics, which suggests that under extremely high energies, quarks can become ‘deconfined’.
  • This deconfined state, called quark-gluon plasma, has been briefly observed in high-energy lead ion collisions at the Large Hadron Collider, reminiscent of the early universe conditions postulated by the Big Bang theory.
  • This plasma indicates a phase where quarks are not bound into clumps, potentially leading to phenomena like quark stars, an area still under exploration in physics.

When quarks clump:

• Two recent studies have advanced our understanding of how quarks, the fundamental constituents of matter, group together.
  • The first study found that clumps of three quarks are more likely to form than clumps of two when certain types of quarks are densely surrounded by other particles, challenging traditional particle physics models that view quark consolidation as independent of surrounding particles.
  • The second study observed clumps made entirely of heavier quarks, which unlike the more stable, lighter-quark clumps found in protons and neutrons, are very short-lived and difficult to study.
• Despite these challenges, understanding heavy-quark clumps is crucial for a complete picture of quark behavior, which influences key processes such as nuclear fusion and the evolution of stars, including potentially in quark stars.

The tension of every star:

• A star maintains its existence by balancing two opposing forces: gravity, which pulls its mass inward, and the nuclear force from fusion reactions in its core, which pushes outward.
• This equilibrium enables the star to shine. However, once a star exhausts its nuclear fuel, gravity begins to dominate, leading to the star’s collapse and eventual death.
• The outcome of this collapse—whether the star ends up as a white dwarf, a neutron star, or a black hole—depends on its mass.
  • For instance, if the Sun were 20 times more massive, it could collapse into a black hole, and if it were 8 times heavier, it might become a neutron star.
• This raises a question about the existence of stars with specific mass ranges that might collapse into neither a neutron star nor a black hole but instead become a quark star.

Enter ‘quark matter’:

• In neutron stars, extreme pressures may convert all protons and electrons into neutrons due to the intense gravitational collapse, giving these stars their name.
• However, a longstanding question in physics is whether these neutrons might be further compressed into quark matter, a hypothetical state consisting solely of quarks.
• Researchers from the University of Helsinki reported that there is an 80-90% likelihood that the cores of the most massive neutron stars contain quark matter.
• These results are preliminary, and more data is needed to confirm the presence of quark matter and understand its properties fully.
• The Tolman-Oppenheimer-Volkoff equation, used in neutron star physics, incorporates data about physical properties to predict other attributes, including the probability of quarks being present in neutron stars.

Neutron stars:

• A neutron star is the collapsed core of a massive supergiant star.
• The stars that later collapse into neutron stars have a total mass of between 10 and 25 solar masses, possibly more if the star was especially rich in elements heavier than hydrogen and helium.
• Except for black holes, neutron stars are the smallest and densest known class of stellar objects.

Black hole:

• A black hole is a region of spacetime where gravity is so strong that nothing, including light and other electromagnetic waves, is capable of possessing enough energy to escape it.
• Einstein’s theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.
• The boundary of no escape is called the event horizon.
• A black hole has a great effect on the fate and circumstances of an object crossing it, but it has no locally detectable features according to general relativity.
• In many ways, a black hole acts like an ideal black body, as it reflects no light.

Source: TH