R Apodis

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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]
Distance 413 ± 5  ly
(127 ± 1  pc)
Absolute magnitude  (MV)−0.22±0.16 [7]
Details [6]
Mass 1.10±0.18  M☉
Radius 22.9±1.65  R☉
Luminosity 293+9
−10 [1]   L☉
Surface gravity (log g)1.99±0.05  cgs
Temperature 4,318±18  K
Metallicity [Fe/H]−0.29±0.05  dex
Rotational velocity (v sin i)2.64±0.45 km/s
Age 5.68±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
SIMBAD data

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]

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References

  1. 1 2 3 4 5 6 7 8 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN   0004-6361. S2CID   17128864.
  3. 1 2 Keenan, Philip C; McNeil, Raymond C (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  4. ↑ Cousins, A. W. J. (1977). "Cape UBV magnitudes and colours of South circumpolar stars". South African Astronomical Observatory Circulars. 1: 51. Bibcode:1977SAAOC...1...51C.
  5. 1 2 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  6. 1 2 3 4 5 6 Jofré, E; Petrucci, R; Saffe, C; Saker, L; de la Villarmois, E. Artur; Chavero, C; Gómez, M; Mauas, P. J. D (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics. 574: A50. arXiv: 1410.6422 . Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. S2CID   53666931.
  7. 1 2 da Silva, L.; et al. (November 2006). "Basic physical parameters of a selected sample of evolved stars". Astronomy and Astrophysics. 458 (2): 609–623. arXiv: astro-ph/0608160 . Bibcode:2006A&A...458..609D. doi:10.1051/0004-6361:20065105. S2CID   9341088.
  8. ↑ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
  9. ↑ Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv: 0806.2878 . Bibcode:2008MNRAS.389..869E. doi: 10.1111/j.1365-2966.2008.13596.x . eISSN   1365-2966. ISSN   0035-8711. S2CID   14878976.
  10. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv: 1709.01160 . Bibcode:2017MNRAS.472.3805G. doi: 10.1093/mnras/stx2219 . eISSN   1365-2966. ISSN   0035-8711. S2CID   118879856.
  11. ↑ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. S2CID   116966328.
  12. ↑ Gaposchkin, Cecilia Helena Payne; Gaposchkin, Sergei; Menzel, Donald Howard (1952). "Variable stars in Milton field 54". Annals of Harvard College Observatory. 115: 1–10. Bibcode:1952AnHar.115....1P.
  13. ↑ Keenan, P. C.; Pitts, R. E. (April 1980). "Revised MK spectral types for G, K ANS M stars". The Astrophysical Journal Supplement Series. 42: 541–563. Bibcode:1980ApJS...42..541K. doi: 10.1086/190662 . ISSN   0067-0049.
  14. ↑ Perryman, M. A. C.; Lindegren, L.; Kovalevsky, J.; Hoeg, E.; Bastian, U.; Bernacca, P. L.; Crézé, M.; Donati, F.; Grenon, M.; Grewing, M.; van Leeuwen, F. (July 1997). "The HIPPARCOS Catalogue". Astronomy and Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P. ISSN   0004-6361.
  15. ↑ De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars V: Southern stars *". Astronomy & Astrophysics. 561: A126. arXiv: 1312.3474 . Bibcode:2014A&A...561A.126D. doi: 10.1051/0004-6361/201220762 . eISSN   1432-0746. ISSN   0004-6361. S2CID   54046583.


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