R Geminorum

R Geminorum (R Gem) is a Mira variable and technetium star in the constellation Gemini. When at maximum light its apparent visual magnitude usually is between 6 and 7, while at minimum light it is typically near magnitude 14.[2] It is located approximately 575 parsecs (1,880 ly) away.[1]

R Geminorum
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Gemini
Right ascension  07h 07m 21.27095s[1]
Declination +22° 42′ 12.7077″[1]
Spectral typeS3.5-6.5/6e
Other designations
BD+22 1577, HD 53791, HIP 34356, HR 2671, SAO 79070

It is one of the brightest known examples of an S-type star, a type that is similar to M-type star, but whose spectra shows zirconium oxide, yttrium oxide and technetium.[3] These exotic elements are formed in the star's core. Technetium has a half-life of just 4.2 million years, so it must have been brought up from the core relatively recently. R Gem has an unusual amount of it, even for an S-type star.[3]

References
  1. "R Geminorum". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 20 January 2014.
  2. "Light Curve Generator". American Association of Variable Star Observers. Retrieved 17 February 2015.
  3. MacRobert, Alan (January 2015). "Weird R Gem Climbs to Maximum". Sky & Telescope. 129 (1): 51.


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