Astronomy:R Aquilae
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[1] mas/yr Dec.: −68.042[1] mas/yr |
| Parallax (π) | 4.2030 ± 0.4306[1] mas |
| Distance | approx. 780 ly (approx. 240 pc) |
| Details | |
| Mass | 1.0[3] M☉ |
| Radius | 259±67[6] R☉ |
| Luminosity | 3,470±50[3] L☉ |
| Temperature | 3,000±300[3] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
R Aquilae is a variable star in the equatorial constellation of Aquila. It is located approximately 780 light years distant from the Sun based on parallax,[1] 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.[6] It is oxygen-rich in abundance with the same mass as the Sun but has expanded to 259[6] times the Sun's radius. On average, the star is radiating 3,470 K[3] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3000 K or so. It is losing mass at the rate of (6 – 35) × 10−7 M☉ yr−1, forming a dusty silicate shell.[3]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 2.4 Samus, N. N. et al. (2017). "General Catalogue of Variable Stars". Astronomy Reports. 5.1 61 (1): 80–88. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Zhao-Geisler, R. et al. (2012). "Dust and molecular shells in asymptotic giant branch stars". Astronomy & Astrophysics 545: A56. doi:10.1051/0004-6361/201118150. Bibcode: 2012A&A...545A..56Z.
- ↑ 4.0 4.1 4.2 "R Aql". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=R+Aql.
- ↑ 5.0 5.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G.
- ↑ 6.0 6.1 6.2 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. doi:10.1086/342282. Bibcode: 2002AJ....124.1706V.
- ↑ "R Aquilae". AAVSO Website. American Association of Variable Star Observers. January 4, 2011. http://www.aavso.org/vsx/index.php?view=detail.top&oid=1140.
- ↑ 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. doi:10.1086/190318. Bibcode: 1974ApJS...28..271K.
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