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 | 763±29 ly (234±9 pc) |
| Details | |
| Mass | 1.0[3] M☉ |
| Radius | 275[6][lower-alpha 1] 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 magnitude 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.
The discovery of R Aquilae was announced by Friedrich Wilhelm Argelander on May 20, 1856. It had been under observation by Argelander and his colleagues at Bonn Observatory since 1854. No name was given to the star in Argelander's announcement, but by October of 1856 it was being called R Aquilae, its variable star designation, in the astronomical literature.[9][10][7]
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.[11] The star may have recently undergone a helium flash.[12] 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
- ↑ 1.0 1.1 1.2 1.3 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 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 6.3 6.4 Montargès, M.; Cannon, E.; Koter, A. de; Khouri, T.; Lagadec, E.; Kervella, P.; Decin, L.; McDonald, I. et al. (2023-03-01). "The VLT/SPHERE view of the ATOMIUM cool evolved star sample - I. Overview: Sample characterization through polarization analysis" (in en). Astronomy & Astrophysics 671: A96. doi:10.1051/0004-6361/202245398. ISSN 0004-6361. https://www.aanda.org/articles/aa/abs/2023/03/aa45398-22/aa45398-22.html.
- ↑ 7.0 7.1 "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.
- ↑ Argelander, Friedrich Wilhelm August (June 1856). "Planeten-Oppositionen, beobachtet am Bonner Meridian kreise von Herrn Prof. Argelander, Dir. der Sternw. zu Bonn". Astronomische Nachrichten 43: 331. Bibcode: 1856AN.....43Q.331A. https://articles.adsabs.harvard.edu/pdf/1856AN.....43Q.331A. Retrieved 21 November 2024.
- ↑ Gould, B. A. (October 1856). "Observations of the variable stars". Astronomical Journal 4 (96): 190–191. doi:10.1086/100548. Bibcode: 1856AJ......4..190G. https://articles.adsabs.harvard.edu/pdf/1856AJ......4..190G. Retrieved 21 November 2024.
- ↑ 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.
- ↑ 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.
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