RT Aurigae (RT Aur, 48 Aurigae) is a

yellow supergiant A yellow supergiant (YSG) is a star, generally of spectral type F or G, having a supergiant luminosity class (e.g. Ia or Ib). They are stars that have evolved away from the main sequence, expanding and becoming more luminous. Yellow supergiants ...

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Auriga AURIGA (''Antenna Ultracriogenica Risonante per l'Indagine Gravitazionale Astronomica'') is an ultracryogenic resonant bar gravitational wave detector in Italy. It is at the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nuclea ...

, about 1,500 light years from Earth. RTAurLightCurve

RT Aurigae is an F to G type

Classical Cepheid variable Classical Cepheids (also known as Population I Cepheids, Type I Cepheids, or Delta Cepheid variables) are a type of Cepheid variable star. They are population I variable stars that exhibit regular radial pulsations with periods of a few days to a ...

which varies from magnitude +5.00 to +5.82 with a period of 3.728309 days. The variability was discovered in 1905. It was quickly recognised as a member of the class of Cepheid variables, but their nature was not understood at that time. Radial velocity changes were detected corresponding to the brightness variations, but the idea that these were caused by stellar pulsations and temperature changes was largely dismissed in favour of orbital motions of a binary star. More accurate observations eventually proved beyond doubt that the brightness variations were caused by pulsations in the atmospheres of the stars, with the stars being smallest and hottest near maximum brightness. RT Aurigae has been suspected to be a spectroscopic binary system, but this has not been confirmed. The strongest evidence was found in 2013 using

CHARA array The CHARA (Center for High Angular Resolution Astronomy) array is an optical interferometer, located on Mount Wilson, California. The array consists of six telescopes operating as an astronomical interferometer. Construction was completed in 20 ...

optical interferometry Interferometry is a technique which uses the '' interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...

. The companion would be 6.7 magnitudes fainter than the supergiant primary, cooler and fainter than an F0

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

star. The two stars are separated by 2.1 milli-arc seconds.

References

{{DEFAULTSORT:RT Aurigae Aurigae, 48 045412 030827 Auriga (constellation) Classical Cepheid variables F-type supergiants Aurigae, RT 2332 BD+30 1238 G-type supergiants