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Neutron Stars: The ‘Death’ of a Death Star
Introduction: Neutron stars are dense, compact masses of subatomic particles (called ‘fermions’) compressed by great gravitational forces (Reisenegger 1). They are classified into three groups: the radio pulsars, which are rotating neutron stars that are predictable pulsators of radio waves due to its fast (Landau n. p.; Reisenegger 2) although sometimes slow (Fuller, et al. 1) rotation; magnetars, which neutron stars with the strongest magnetic fields in the universe and violently burst high-energy X-ray and gamma rays (Landau n. p.); nonrotating binary neutron stars, which are emitters of x-rays (Reisenegger 3); and PSR J1119-6127, which are behaving alternatively like radio pulsars and then magnetars (Landau n. p.). In effect, neutron stars are core remnants of huge exploded stars.
Neutron stars emerged from nebulae. The planetary nebula stage is the final stage of giant red stars, which have masses of up to eight times the Sun’s mass (Santander-Garcia, et al. 63). As the Asymptotic Giant Branch (AGB) stars expand, gases overfill the region surrounding the stars (called ‘Roche lobe’). The excess pressure is generated, eventually creating a common gaseous stellar envelope around the primary and the secondary stars. Resultant unbinding of the gravitational forces eject the envelope, resulting into a heavy rain of iron free-falling at the speed of light and forming a two-poled planetary nebula and giving birth to a white dwarf. Neutron stars follow the same process of birth but involving a more massive star with at least 10 solar masses and massive supernovae (Foglizzo 1).
The Death Phase: Like “normal” stars, ordinary nonrotating neutron stars increase in mass. However, unlike normal stars, they have limits to their growth. Although it can take thousands of years, the maximum mass, the upper limit of the neutron star’s mass capacity or a level of pressure that their thick crust cannot sustain without collapsing to, or transforming into, a black whole, will be reached eventually (“When Will a Neutron Star Collapse” n. p.). When that happens, the nonrotating stars will be transformed into two alternative states.
The Final or Merely Alternative State: When the maximum mass is reached, a neutron stars have two alternative transformational paths. First, it can collapse into a black hole, an area in the outer space so strong even is trapped in it like heat reservoirs (Opatrny and Richterek 67). Second, it can also into a rotating star, called a rotating neutron star. Unlike the stationary neutron star, the centrifugal force developed in a rotating star balances the gravitational force, which seeks to push the limit of the neutron star (“When Will a Neutron Star Collapse” n. p.). Astrophysicists estimated that the centrifugal force can allow the neutron star to increase its mass up to 20 percent (“When Will a Neutron Star Collapse” n. p.). However, a limit to the increase in the star’s mass exists as there is a limit to the speed of rotation wherein the mass of the neutron star continues to increase, beyond which the rotating star will break apart.
Conclusion: There is much to know about neutron stars. The recent discovery of PSR J1119-6127, apparently a transition type of neutron stars, keep this group of stars alone still relentlessly interesting. An important lesson of death in this type of “death” stars, however, emerge with certainty. Perhaps there is no death at all as the massive red stars underwent supernova explosions, which simply transformed them into neutron stars and conversely either transform into rotating neutron stars or into a black hole.
Moreover, who says that black holes do not exist?
Works Cited
“When Will a Neutron Star Collapse To a Black Hole?” Phys.org. 7 Apr. 2016. Web. https://phys.org/news/2016-04-neutron-star-collapse-black-hole.html.
Foglizzo, T. “Explosion Physics of Core-Collapse Supernovae”. (1-21). In Handbook of Supernovae. Alsabti, Athem W. and Paul Murdin (Eds.). Switzerland: Springer International Publishing. Web. http://link.springer.com/referenceworkentry/10.1007/978-3-319-20794-0_52-1#page-1.
Fuller, Jim, Matteo Cantiello, Daniel Lecoanet, and Eliot Quataert. “The Spin Rate of Pre-Collapse Stellar Cores: Wave Driven Angular Momentum Transport in Massive Stars. The Astrophysical Journal Feb. 2015. PDF file.
Landau, Elizabeth. “The Case of the ‘Missing Link’ Neutron Star”. NASA 7 Jan. 2017. Web. https://www.nasa.gov/feature/jpl/the-case-of-the-missing-link-neutron-star.
Opatrny, Tomas and Lukas Richterek. “Black Hole Heat Engine”. American Journal of Physics Jan. 2012: 67-71. PDF file.
Reisenegger, Andreas. “Magnetic Fields of Neutron Stars: An Overview”. ASP Conference Series 2001: 1-11. PDF file.
Santander-Garcia, M., P. Rodriguez-Gil, R.L.M. Corradi, D. Jones, B. Miszalski, H.M.J. Boffin, M.M. Rubio-Diez, and M.M. Kotze. “The Double-Degenerate, Super-Chandrasekhar Nucleus of the Planetary Nebula Henize 2-428”. Nature 9 Feb. 2015, 519(7541): 63-65. Web. http://www.nature.com/nature/journal/v519/n7541/pdf/nature14124.pdf.
