Red giant star in the constellation Aquila
R Aquilae light curve
R Aquilae is a variable star in the equatorial constellation of Aquila . It is located approximately 760 light years distant from the Sun[6] and is drifting further away with a radial velocity of 35 km/s.[5] This is a thermally-pulsating Mira variable that ranges in brightness from 5.3 down to 12.0 with a period of 269.84 days.[2] [7] The period was over 300 days when first observed, and has declined steadily since – decreasing from 320 in 1915 down to 264 in 2010, at an average rate of 0.4 days per year. The amplitude of the variation has also decreased by about a magnitude since discovery.[8] The peak magnitude is bright enough for the star to be visible to the naked eye as a dim, red-hued star.
R Aquilae is an aging red giant on the asymptotic giant branch [3] with a stellar classification that varies over time, between M5e and M9e,[2] where the 'e' suffix indicates emission features in the spectrum . The cooler spectral types occur near the minimum visual magnitude, and the hottest near maximum.[9] The star may have recently undergone a helium flash .[10] It is oxygen-rich in abundance with the same mass as the Sun but has expanded to 275[6] times the Sun's radius . On average, the star is radiating 3,470[3] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 2,800 K or so.[6] It is losing mass at the rate of (6 – 35) × 10−7 M ☉ yr−1 , forming a dusty silicate shell.[3]
Notes
^ Calculated using angular diameter and distance in Table 1
References
^ a b c d Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties" . Astronomy & Astrophysics . 616 . A1. arXiv :1804.09365 . Bibcode :2018A&A...616A...1G . doi :10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR .
^ a b c d e Samus, N. N.; et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports . 5.1. 61 (1): 80–88. Bibcode :2017ARep...61...80S . doi :10.1134/S1063772917010085 . S2CID 125853869 .
^ a b c d e f Zhao-Geisler, R.; et al. (2012). "Dust and molecular shells in asymptotic giant branch stars". Astronomy & Astrophysics . 545 : A56. arXiv :1207.3767 . Bibcode :2012A&A...545A..56Z . doi :10.1051/0004-6361/201118150 . S2CID 53992211 .
^ a b c "R Aql" . SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-08-17 .
^ a b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 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 d e f Montargès, M.; Cannon, E.; Koter, A. de; Khouri, T.; Lagadec, E.; Kervella, P.; Decin, L.; McDonald, I.; Homan, W.; Waters, L. B. F. M.; Sahai, R.; Gottlieb, C. A.; Malfait, J.; Maes, S.; Pimpanuwat, B. (2023-03-01). "The VLT/SPHERE view of the ATOMIUM cool evolved star sample - I. Overview: Sample characterization through polarization analysis" . Astronomy & Astrophysics . 671 : A96. arXiv :2301.02081 . doi :10.1051/0004-6361/202245398 . ISSN 0004-6361 .
^ VSX; Otero, Sebastian (January 4, 2011). "R Aquilae" . AAVSO Website . American Association of Variable Star Observers . Retrieved 2013-12-21 .
^ Greaves, J; Howarth, J. J. (June 2000). "Further investigations of R Aquilae". Journal of the British Astronomical Association . 110 (3): 131–142. Bibcode :2000JBAA..110..131G .
^ Keenan, Philip C.; et al. (1974). "Revised Catalog of Spectra of Mira Variables of Types ME and Se" . Astrophysical Journal Supplement . 28 : 271. Bibcode :1974ApJS...28..271K . doi :10.1086/190318 .
^ Van Belle, G. T.; et al. (2002). "Angular Size Measurements of Mira Variable Stars at 2.2 Microns. II". The Astronomical Journal . 124 (3): 1706–1715. arXiv :astro-ph/0210167 . Bibcode :2002AJ....124.1706V . doi :10.1086/342282 . S2CID 33832649 .