Lacerta

Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard. A small, faint constellation, it was created in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a "W" shape similar to that of Cassiopeia, and it is thus sometimes referred to as 'Little Cassiopeia'. It is located between Cygnus, Cassiopeia and Andromeda on the northern celestial sphere. The northern part lies on the Milky Way.

Notable features

Lacerta is typical of Milky Way constellations: no bright galaxies, nor globular clusters, but instead open clusters, for example NGC 7243, the faint planetary nebula IC 5271 and quite a few double stars. It also contains the prototypic blazar BL Lacertae. Lacerta contains no Messier objects.

Stars

• α Lac: this main sequence star of spectral type A1 V has an apparent magnitude of merely 3.77; Lacerta has no other stars brighter than fourth magnitude. α Lac is an optical double star.
• Roe 47: a multiple star consisting of five components (magnitudes 5.8, 9.8, 10.1, 9.4, 9.8).
• ADS 16402 is a binary star system in Lacerta, around which a planet orbits with some unusual properties.^[1] The Jupiter-sized planet exhibits an unexpectedly low density, about the same as cork. This planet is dubbed HAT P-1.

Deep-sky objects

• NGC 7243: an open star cluster of approximately 6.4m.
• BL Lacertae: it was discovered quite early and first thought to be a star and therefore given a variable star designation. However, in reality it is the core of a galaxy. It lent its name to a whole type of celestial objects, the BL Lacertae objects (a subtype of blazar.) The object varies irregularly between magnitudes 14 and 17 over a few days.

History

Centred on a region of the sky without apparently bright stars, Lacerta was not regarded as a constellation by ancient astronomers. Before Johannes Hevelius'es creation of the constellation, this area, including the "rock of" Andromeda, was assembled by Royer to form the constellation Sceptrum et Manus Iustitiae. Later, when Lacerta sive Stellio was established, Bode created the constellation Frederici Honores for the dropped "rock of" Andromeda part. Both Sceptrum et Manus Iustitiae and Frederici Honores are now obsolete and not used by astronomers, while Lacerta still survives.

Equivalents

Coincidentally, the Chumash people of California call this part of the sky 'Lizard' and include it in multiple stories.

Namesakes

USS Lacerta (AKA-29) was an attack cargo ship in the United States navy named after the constellation.

Citations

References

• Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.

External links

• The Deep Photographic Guide to the Constellations: Lacerta
• Star Tales – Lacerta
• Weasner's Mighty ETX Site, GO TO LACERTA (a constellation guide for amateur astronomers)

Coordinates: 22^h 30^m 00^s, +45° 00′ 00″