Tuesday, September 14, 2021

Astronomers discover a new type of star pulsar

 Four new stars have been identified that vary in brightness by 5%;  the Sun's luminosity varies only 0.1%

 Scientists discovered four stars of a new type never seen before and called them hot sub-dwarf pulsars.  In astronomy, pulsars are rapidly rotating neutron stars that are left behind when a massive star explodes.

 Many stars pulsate, even the Sun on a very small scale”, explained physicist Tmas Kupfer, from the University of California at Santa Barbara, in the United States.  "Those stars with the most changing brightness are usually radial pulsating."

 According to the scientist, pulsars behave as if they "breathe", inhaling and exhaling while the star changes size.  In the case of the hot sub-dwarf pulsar, researchers believe there is a mechanism behind the oscillations, but they don't yet know it very well.  The hypothesis is that the pulse is produced by iron, which creates an energy layer.

 Astronomers took data from California's Palomar Observatory and noticed that the four discovered stars pulsed on a scale every 200 and 475 seconds.  Brightness varied by 5%, with the Sun's luminosity varying by only 0.1%.

 According to the study, the new stars are extremely hot – they can reach up to almost 50,000 °C (the Sun's temperature reaches 5,000 °C).  Sub-dwarf pulsars are one-tenth the diameter of the Sun and have an astronomically low mass, ranging from 20% to 50% the mass of the Solar System's large star.

 Because these stars have a small mass, astronomers believe they began their lives much like the Sun: they fused hydrogen to helium in their cores.  After the hydrogen runs out, they expand and start fusing the helium.  However, in the case of hot sub-dwarf pulsars, their core material may have been “stolen” by some other celestial body before the helium got hot to perform fusion.

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 REPRESENTATION OF A HOT SUB-DWARF STAR (PHOTO: CAMBRIDGE UNIVERSITY )


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