R Aquilae

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]
Distance763±29 ly
(234±9 pc)[6]
Details
Mass1.0[3] M☉
Radius275[6][a] R☉
Luminosity3,470±50[3] L☉
Temperature2,800[6] K
Other designations
R Aql, BD+08°3970, HD 177940, HIP 93820, HR 7243, SAO 124266[4]
Database references
SIMBADdata
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]

  1. ^ a b c d Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference zg was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference montarges was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference AAVSO was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Greaves was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Keenan1974 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference vb was invoked but never defined (see the help page).


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