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For example, if a TNO is incorrectly assumed to have a mass of 3.59 × 10 20 kg based on a radius of 350 km with a density of 2 g/cm 3 but is later discovered to have a radius of only 175 km with a density of 0.5 g/cm 3, its true mass would be only 1.12 × 10 19 kg.
Kepler-51 is a small G-type star, with a slightly lower radius, mass and effective temperature than the Sun. It is a young star, less than one billion years old, and hence is highly active compared to the Sun. Around 4 to 6% of the star's surface is covered by starspots. Its EUV and X-ray fluxes are likely influencing the chemistry, dynamics ...
Brown dwarfs are substellar objects that have more mass than the biggest gas giant planets, but less than the least massive main-sequence stars.Their mass is approximately 13 to 80 times that of Jupiter (M J) [2] [3] —not big enough to sustain nuclear fusion of ordinary hydrogen (1 H) into helium in their cores, but massive enough to emit some light and heat from the fusion of deuterium (2 H).
It was initially estimated to have a much lower mass, and thus a low density of 3.3 ± 0.9 g/cm 3 and a surface gravity around 6.1 m/s 2 (62% of Earth's value). [1] This suggested a large amount of volatiles , with a 2017 study suggesting that a water ocean may comprise as much as 20% of the planet's mass, increasing the temperature at the ...
However, using an astronomical interferometer, measurements of the radius of the star can be made directly to an accuracy of 0.5%. [2] Through such means, the radius of Tau Ceti has been measured to be 79.3% ± 0.4% of the solar radius. [2] This is about the size that is expected for a star with somewhat lower mass than the Sun. [30]
Based on results from the Gaia telescope's second data release from April 2018, an estimated 694 stars will approach the Solar System to less than 5 parsecs in the next 15 million years. Of these, 26 have a good probability to come within 1.0 parsec (3.3 light-years) and another 7 within 0.5 parsecs (1.6 light-years). [ 3 ]
Radius is semi-major axis, angle orbital inclination. The Haumea or Haumean family is the only identified trans-Neptunian collisional family ; that is, the only group of trans-Neptunian objects (TNOs) with similar orbital parameters and spectra (nearly pure water-ice) that suggest they originated in the disruptive impact of a progenitor body. [ 1 ]
An IAU 2006 press release [51] question-and-answer section estimated that objects with mass above 0.5 × 10 21 kg and radius greater than 400 km would "normally" be in hydrostatic equilibrium (the shape ... would normally be determined by self-gravity), but that all borderline cases would need to be determined by observation. [51]