R Aquilae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 06m 22.25105s[1] |
| Declination | +08° 13′ 48.0004″[1] |
| Apparent magnitude (V) | 5.3 to 12.0[2] |
| Characteristics | |
| Evolutionary stage | AGB[3] |
| Spectral type | M5-9IIIe[2] |
| U−B color index | 0.37[4] |
| B−V color index | 1.60[4] |
| Variable type | Mira[2] |
| Astrometry | |
| Radial velocity (Rv) | 34.6±0.6[5] km/s |
| Proper motion (μ) | RA: +4.404 mas/yr[1] Dec.: −68.042 mas/yr[1] |
| Parallax (π) | 4.2030 ± 0.4306 mas[1] |
| Distance | 763±29 ly (234±9 pc)[6] |
| Details | |
| Mass | 1.0[3] M☉ |
| Radius | 275[6][a] R☉ |
| Luminosity | 3,470±50[3] L☉ |
| Temperature | 2,800[6] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
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
[edit]- ^ Calculated using angular diameter and distance in Table 1
References
[edit]- ^ 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.
