R Apodis

R Apodis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Apus
Right ascension 14h 57m 52.98352s[1]
Declination −76° 39′ 45.5569″[1]
Apparent magnitude (V) 5.36±0.01[2]
Characteristics
Spectral type K4 III:[3]
B−V color index +1.44[4]
Variable type constant[5]
Astrometry
Radial velocity (Rv)−31.20±0.08[6] km/s
Proper motion (μ) RA: −69.161 mas/yr[1]
Dec.: −16.583 mas/yr[1]
Parallax (π)7.8879 ± 0.0867 mas[1]
Distance413 ± 5 ly
(127 ± 1 pc)
Absolute magnitude (MV)−0.22±0.16[7]
Details[6]
Mass1.10±0.18 M☉
Radius22.9±1.65 R☉
Luminosity293+9
−10[1] L☉
Surface gravity (log g)1.99±0.05 cgs
Temperature4,318±18 K
Metallicity [Fe/H]−0.29±0.05 dex
Rotational velocity (v sin i)2.64±0.45 km/s
Age5.68±2.42 Gyr
Other designations
18 G. Apodis[8], R Aps, CD−76°688, CPD−76°924, FK5 3175, GC 20057, HD 131109, HIP 73223, HR 5540, SAO 257212
Database references
SIMBADdata

R Apodis (HD 131109; HR 5540; 18 G. Apodis) is a solitary star[9] in the constellation Apus. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.36.[2] Parallax measurements imply a distance of 413 light-years[1] and it is drifting closer with a heliocentric radial velocity of −31.2 km/s.[6] At its current distance, R Apodis' brightness is diminished by an interstellar extinction of 0.26 magnitudes[10] and it has an absolute magnitude of −0.22.[7]

HD 131109 was the first star observed to be variable in the constellation; It was first discovered in 1873 by Benjamin Apthorp Gould. Later, it was hastily given the variable star designation R Apodis in a 1907 variable star catalogue despite it being a suspected variable star at the time.[11] However, observations conducted in a 1952 field star survey revealed that R Apodis was not variable at all.[12] Keenan & Pitts (1980) found that it varied between magnitudes 5.5 and 6.1, but this was never confirmed.[13] Hipparcos photometric data revealed that R Apodis indeed had a constant brightness.[14] It has since been listed as a class CST: in the General Catalog of Variable Stars.[5]

R Apodis has a stellar classification of K4 III:,[3] indicating that it is an evolved K-type giant that has ceased hydrogen fusion at its core and left the main sequence. However, there is uncertainty about the luminosity class. It has a comparable mass to the Sun at 1.1 solar masses but, at the age of 5.68 billion years, it has expanded to 23 times the radius of the Sun.[6] It radiates 293 times the luminosity of the Sun[1] from its enlarged photosphere at an effective temperature of 4,318 K.[6] R Apodis is metal deficient with an iron abundance roughly half of the Sun's[6] and it spins slowly with a projected rotational velocity lower than 1.3 km/s.[15]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Tycho2000 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference perkins was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Cousins1977 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference jofre was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference aaa458_2_609 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Gontcharov2017 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Cannon1907 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Gaposchkin1952 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Keenan1980 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Perryman1997 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference De Medeiros2014 was invoked but never defined (see the help page).