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.
| 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] |
| Distance | 2,800 ± 200 ly (850 ± 70 pc) |
| Details | |
| Radius | 431[5] R☉ |
| Luminosity | 5,500[5] L☉ |
| Temperature | 2,400[5] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
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]
References
edit- ^ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ^ a b c d 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.
- ^ 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.
- ^ a b c 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.
- ^ "R Geminorum". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 20 January 2014.
- ^ "Light Curve Generator". American Association of Variable Star Observers. Archived from the original on February 17, 2015. Retrieved 17 February 2015.
- ^ a b MacRobert, Alan (January 2015). "Weird R Gem Climbs to Maximum". Sky & Telescope. 129 (1): 51. Bibcode:2015S&T...129a..51M.