Taxus Baccata

by | Mar 15, 2018 | Taxus Baccata

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Not to be confused with RR Lyrae.
R Lyrae near Vega

R Lyrae, also known as its Flamsteed designation 13 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.[8] It is one of the brightest stars at the K band, having an apparent magnitude of −2.08, only 14 stars are brighter.[9]

Visual band light curves for R Lyrae, adapted from Percy et al. (2001)[10]

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.[4][11]

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.[6]

Notes

  1. ^ Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
    .
  2. ^ Calculated using the absolute bolometric magnitude of R lyrae, with respect to the Sun's absolute bolometric magnitude of 4.83:
    100.4(4.74+(−4.3) = 4130.48.

References

  1. ^ a b c d e van Leeuwen, Floor (13 August 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. eISSN 1432-0746. ISSN 0004-6361.
  2. ^ a b c d Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. ^ a b "GCVS Query=R Lyr". General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2012-08-22.
  4. ^ a b c 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. Bibcode:2004MNRAS.355..601Y. doi:10.1111/j.1365-2966.2004.08344.x.
  5. ^ Famaey, B.; Pourbaix, D.; Frankowski, A.; Van Eck, S.; Mayor, M.; Udry, S.; Jorissen, A. (2009). "Spectroscopic binaries among Hipparcos M giants,. I. Data, orbits, and intrinsic variations". Astronomy and Astrophysics. 498 (2): 627. arXiv:0901.0934. Bibcode:2009A&A...498..627F. doi:10.1051/0004-6361/200810698. S2CID 18739721.
  6. ^ a b c d e Halabi, Ghina M.; Eid, Mounib El (2015). "Exploring masses and CNO surface abundances of red giant stars". Monthly Notices of the Royal Astronomical Society. 451 (3): 2957. arXiv:1507.01517. Bibcode:2015MNRAS.451.2957H. doi:10.1093/mnras/stv1141. S2CID 118707332.
  7. ^ Prugniel, Ph.; Vauglin, I.; Koleva, M. (2011). "The atmospheric parameters and spectral interpolator for the MILES stars". Astronomy & Astrophysics. 531: A165. arXiv:1104.4952. Bibcode:2011A&A...531A.165P. doi:10.1051/0004-6361/201116769. S2CID 54940439.
  8. ^ 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. arXiv:1201.5315. Bibcode:2012A&A...539A..86J. doi:10.1051/0004-6361/201118375. S2CID 53404166.
  9. ^ Kmag < -2.08. SIMBAD.
  10. ^ Percy, John R.; Wilson, Joseph B.; Henry, Gregory W. (August 2001). "Long-Term VRI Photometry of Small-Amplitude Red Variables. I. Light Curves and Periods". Publications of the Astronomical Society of the Pacific. 113 (786): 983–996. Bibcode:2001PASP..113..983P. doi:10.1086/322153. S2CID 14609175.
  11. ^ Glass, I. S.; Van Leeuwen, F. (2007). "Semiregular variables in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society. 378 (4): 1543–1549. arXiv:0704.3150. Bibcode:2007MNRAS.378.1543G. doi:10.1111/j.1365-2966.2007.11903.x. S2CID 14332208.
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