An Etymological Dictionary of Astronomy and Astrophysics
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A unit of length, representing the radius of the → Sun, used to express the size of stars in astrophysics. It is equivalent to: 695,700 km, 0.00465047 → astronomical units, 7.35355 × 10^-8 → light-years, and 2.32061 → light-seconds.

→ solar; → radius.

The → radius of a → supernova remnant (SNR) when, at the end of the → free expansion phase, the mass of the swept-up → shell equals that of the ejected gas from the → supernova explosion. It is given by R_SW = (3M_e / 4πρ₀)^(1/3), where M_e is the ejected mass and ρ₀ is the initial density of the → interstellar medium.

Sweep, from M.E. swepen, from O.E. swapan "to sweep;" cognate with Ger. schweifen; → up; → radius.

Šo'â', → radius; rubeš, noun from ruftan, rubidan "to sweep," → scan.

Same as → Roche limit.

→ tidal; → radius.

The radius centered on a galaxy containing matter at 200 times the → critical density of the Universe.

→ virial; → radius.