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Black dwarf. A black dwarf is a theoretical stellar remnant, specifically a white dwarf that has cooled sufficiently to no longer emit significant heat or light. Because the time required for a white dwarf to reach this state is calculated to be longer than the current age of the universe (13.8 billion years), no black dwarfs are expected to ...
In red dwarf systems, gigantic stellar flares which could double a star's brightness in minutes [92] and huge starspots which can cover 20% of the star's surface area, [93] have the potential to strip an otherwise habitable planet of its atmosphere and water. [94] As with more massive stars, though, stellar evolution changes their nature and ...
The surface gravity of a white dwarf is very high, and of a neutron star even higher. A white dwarf's surface gravity is around 100,000 g (10 6 m/s 2) whilst the neutron star's compactness gives it a surface gravity of up to 7 × 10 12 m/s 2 with typical values of order 10 12 m/s 2 (that is more than 10 11 times that of Earth).
Stellar structure. Cross-section of the Sun. Stellar structure models describe the internal structure of a star in detail and make predictions about the luminosity, the color and the future evolution of the star. Different classes and ages of stars have different internal structures, reflecting their elemental makeup and energy transport ...
The closest encounter to the Sun so far predicted is the low-mass orange dwarf star Gliese 710 / HIP 89825 with roughly 60% the mass of the Sun. [4] It is currently predicted to pass 0.1696 ± 0.0065 ly (10 635 ± 500 au) from the Sun in 1.290 ± 0.04 million years from the present, close enough to significantly disturb the Solar System's Oort ...
Protoplanetary disk. Not to be confused with Protoplanetary nebula. A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may not be considered an accretion disk, while the two are similar.
ALMA image of HL Tauri, a protoplanetary disk. In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, into an accretion disk. [1][2] Most astronomical objects, such as galaxies, stars, and planets, are formed by accretion processes.
Brown dwarf stars and gas-giant planets do not achieve sustained fusion, as they contain insufficient mass to gravitationally compress the reactants to the degree required to initiate a reaction. If the density of the star or planet could be increased, fusion could be initiated. One such method is to "seed" the body with a black hole. Although ...