Lacerta
For the biological genus of lizards, see Lacerta.
Lacerta, the Lizard, is one of the 88 official constellations acknowledged by the International Astronomical Union. It is not among Ptolemy's 48 ancient constellations. Instead it was created ca. 1687 by the astronomer Johannes Hevelius. It doesn't contain any really bright stars, no Messier object, no galaxy brighter than 14.5m, no globular clusters and not a single named star. Correspondingly it is rather difficult to find. The northern part lies on the Milky Way. Lacerta is located between Cygnus, Cassiopeia and Andromeda on the northern celestial sphere.
Notable features
- BL Lacerta: it was discovered quite early and first thorught to be a star and therefore named like variable stars. However, in reality it is represents the core of a galaxy. It lent its name to a whole type of celestial objects, the BL Lacerta objects or blazars.
- α Lac: this main sequence star of spectral type A1 V has an apparent magnitude of merely 3.77m. There are no other stars brighter than fourth magnitude. α Lac is an optical double star
- Roe 47: a multiple star consisting of five components (magnitudes 6, 10, 10, 10, 9.5, 10.5),
Notable deep sky objects
- NGC 7243: an open star cluster of approximately 6.4m.
- IC 5217: this planetary nebula is difficult to find. Its apparent size is 6 by 8 arcsec and its brightness is circa 12m.
Mythology
Before Johannes Hevelius adopted the name Lacerta several other names had proposed for this part of the sky, among them Sceptrum (= Sceptre) and Fredrick's Glory. Being a modern constellation there is no real mythology surrounding Lacerta.
In the Science Fiction novel Diaspora by Greg Egan, the constellation Lacerta was the origin of a massive shock wave, caused by the collision of two neutron stars, which caused the extinction of most life on Earth.
External Links
- Weasner's Mighty ETX Site, (a constellation guide for amateur astronomers)
