Astronomy:R Lyrae

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R Lyrae is a 4th magnitude semiregular variable star in the constellation Lyra, approximately 350 light years away from Earth. It is a red giant star of the spectral type M5III, meaning it has a surface temperature of under 3,500 kelvins. It is much larger and brighter, yet cooler, than the Sun. In the near-infrared J band, it is brighter than the nearby Vega.

R Lyrae is unusual in that it is a red star with a high proper motion, greater than 50 milliarcseconds a year.[1]

The variability is not consistent and regular, but periods of 46, 64, 378, and 1,000 days have been reported, with the 46-day period being the strongest.[2][3]

It is calculated that R Lyrae was a 2.0 M star on the main sequence. It is considered an oxygen-rich asymptotic giant branch star, with both hydrogen and helium shells fusing.[4]

References[edit]

  1. Jiménez-Esteban, F. M.; Caballero, J. A.; Dorda, R.; Miles-Páez, P. A.; Solano, E. (2012). "Identification of red high proper-motion objects in Tycho-2 and 2MASS catalogues using Virtual Observatory tools". Astronomy & Astrophysics 539: 12. doi:10.1051/0004-6361/201118375. Bibcode2012A&A...539A..86J. 
  2. Yeşilyaprak, C.; Aslan, Z. (2004). "Period-luminosity relation for M-type semiregular variables from Hipparcos parallaxes". Monthly Notices of the Royal Astronomical Society 355 (2): 601. doi:10.1111/j.1365-2966.2004.08344.x. Bibcode2004MNRAS.355..601Y. 
  3. Glass, I. S.; Van Leeuwen, F. (2007). "Semiregular variables in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society 378 (4): 1543. doi:10.1111/j.1365-2966.2007.11903.x. Bibcode2007MNRAS.378.1543G. 
  4. Halabi, Ghina M.; El Eid, Mounib (2012). "Sensitivity of the blue loops of intermediate-mass stars to nuclear reactions". American Institute of Physics Conference Series 1498 (1): 334. doi:10.1063/1.4768514. Bibcode2012AIPC.1498..334H. 

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