R Geminorum

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

R Geminorum pulsates with an average period of 369.9 days, varying by up to eight magnitudes at visual wavelengths.[2] When at maximum light its apparent visual magnitude is usually between 6 and 7, while at minimum light it is typically near magnitude 14.[6]

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.[7] 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.[7]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics (in press). arXiv:2012.01533. doi:10.1051/0004-6361/202039657. S2CID 227254300. Gaia EDR3 record for this source at VizieR.
  2. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  3. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  4. Ramstedt, S.; Schöier, F. L.; Olofsson, H. (2009). "Circumstellar molecular line emission from S-type AGB stars: Mass-loss rates and SiO abundances". Astronomy & Astrophysics. 499 (2): 515–527. arXiv:0903.1672. Bibcode:2009A&A...499..515R. doi:10.1051/0004-6361/200911730. S2CID 17942939.
  5. "R Geminorum". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 20 January 2014.
  6. "Light Curve Generator". American Association of Variable Star Observers. Retrieved 17 February 2015.
  7. MacRobert, Alan (January 2015). "Weird R Gem Climbs to Maximum". Sky & Telescope. 129 (1): 51.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.