19 Aquarii 19 Aquarii 19 Aquarii is a star in the constellation of Aquarius. With an apparent magnitude of about 5.7, the star is barely visible to the naked eye (see Bortle scale). Parallax estimates made by the Hipparcos spacecraft put it at a distance of about 300 light years (92 parsecs) away from the Earth. 19 Aquarii has a spectral type of A8V, meaning it is an A-type main-sequence star. These types of stars are bluish-white colored, and have effective temperatures between 7100 and 11500 K. It rotates fairly fast, as its projected rotational velocity is about 155 km/s, so it
Unit distance graph find a unit distance graph "G" in which some pair of vertices are at distance "A" in all unit distance representations of "G" . This result implies a finite version of the Beckman–Quarles theorem: for any two points "p" and "q" at distance "A", there exists a finite rigid unit distance graph containing "p" and "q" such that any transformation of the plane that preserves the unit distances in this graph preserves the distance between "p" and "q" . The full Beckman–Quarles theorem states that any transformation of the Euclidean plane (or a higher-dimensional space) that preserves unit distances must