R Geminorum

Not to be confused with Rho Geminorum.
R Geminorum

The visual band light curve of R Geminorum, from AAVSO data[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Gemini
Right ascension 07h 07m 21.271s[2]
Declination +22° 42′ 12.75″[2]
Apparent magnitude (V) 6.0 - 14.0[3]
Characteristics
Evolutionary stage AGB
Spectral type S2,9e-S8,9e(Tc)[3]
Variable type mira[3]
Astrometry
Radial velocity (Rv)−45.2[4] km/s
Proper motion (μ) RA: −8.765[2] mas/yr
Dec.: 0.665[2] mas/yr
Parallax (π)1.1795 ± 0.0960 mas[2]
Distance2,800 ± 200 ly
(850 ± 70 pc)
Details
Radius431[5] R☉
Luminosity5,500[5] L☉
Temperature2,400[5] K
Other designations
BD+22 1577, HD 53791, HIP 34356, HR 2671, SAO 79070[6]
Database references
SIMBADdata

R Geminorum (R Gem) is a Mira variable and technetium star in the constellation Gemini. It is located approximately 850 parsecs (2,800 ly) away.

R Geminorum pulsates with an average period of 369.9 days, varying by up to eight magnitudes at visual wavelengths.[3] When at maximum light its apparent visual magnitude is usually between 6 and 7, while at minimum light it is typically near magnitude 14.[7]

R Geminorum 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.[8] 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.[8]

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  2. ^ a b c d e Cite error: The named reference edr3 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference gcvs was invoked but never defined (see the help page).
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  5. ^ a b c Cite error: The named reference ramstedt2009 was invoked but never defined (see the help page).
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  7. ^ Cite error: The named reference AAVSO was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Sky & Telescope was invoked but never defined (see the help page).