S Apodis

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S Apodis
SApsLightCurve.png
The visual band light curve of S Apodis, from AAVSO data [1]
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Apus
Right ascension 15h 09m 24.53660s [2]
Declination −72° 03′ 45.1828″ [2]
Apparent magnitude  (V)9.6 - 17.0 [3]
Characteristics
Evolutionary stage post-AGB [4]
Spectral type R3 [5]
U−B color index +0.66 [6]
B−V color index +1.26 [6]
Variable type R Coronae Borealis [3]
Astrometry
Radial velocity (Rv)−75.0 [7]  km/s
Proper motion (μ)RA: −6.632  mas/yr [2]
Dec.: −2.155  mas/yr [2]
Parallax (π)0.2243 ± 0.0171  mas [2]
Distance 15,000 ± 1,000  ly
(4,500 ± 300  pc)
Absolute bolometric
magnitude  (Mbol)		−2.68 (at max) [8]
Details
Mass 0.6 or 1 [9]   M☉
Radius 132±9 [10]   R☉
Luminosity 960 [11]   L☉
Temperature 4,500 - 5,115 [12]   K
Other designations
S Aps, CD−71°1120, CPD−71°1743, HD  133444, HIP  74179, 2MASS J15092452-7203451 [13]
Database references
SIMBAD data

S Apodis, also known as HD 133444 is a variable star located in the southern circumpolar constellation Apus. It has an apparent magnitude ranging from 9.6 to 17, [3] which is below the limit for naked eye visibility. The object is located relatively far at a distance of approximately 15,000 light years based on Gaia DR3 parallax measurements, [2] but it is drifting closer with a heliocentric radial velocity of −75  km/s . [7]

HD 133444 has been known to be a variable star since 1896. [14] However, its nature as a carbon star was not observed until 1967 by astronomer Brian Warner. [15] In 1973, HD 133444 was listed as a R Coronae Borealis variable. [16] These are extremely hydrogen-deficient supergiants thought to have arisen as the result of the merger of two white dwarfs [17] and fewer than 100 have been discovered as of 2013. [18] A decade later, S Apodis was observed to have a change it its pulsation mode. [9]

S Apodis has a stellar classification of R3, indicating that it is a R-type carbon star. It has a mass of either 0.6  M☉ or 1 M☉, [9] depending on the model. However, it has expanded to an average radius 132 times that of the Sun. [10] It radiates 960 times the luminosity of the Sun [11] from its photosphere at an effective temperature of 4,500–5,115  K , [12] giving it an orange hue. An infrared excess has been detected around the star, indicating the presence of circumstellar dust. The dust has a temperature of 730 K. [19]

Related Research Articles

R Apodis is a solitary star 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. Parallax measurements imply a distance of 413 light-years and it is drifting closer with a heliocentric radial velocity of −31.2 km/s. At its current distance, R Apodis' brightness is diminished by an interstellar extinction of 0.26 magnitudes and it has an absolute magnitude of −0.22.

<span class="mw-page-title-main">NO Apodis</span> Star in the constellation Apus

NO Apodis is a solitary, red hued variable star located in the southern circumpolar constellation Apus. It has an average apparent magnitude of 5.86, allowing it to be faintly seen with the naked eye. The object is relatively far at a distance of 790 light years but is drifting closer with a heliocentric radial velocity −18.3 km/s.

<span class="mw-page-title-main">Beta Coronae Australis</span> Star in the constellation Corona Australis

Beta Coronae Australis, Latinized from β Coronae Australis, is a solitary star located in the southern constellation Corona Australis. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.10. The star is located around 470 light years distant from the Sun based on parallax, and is drifting further away with a radial velocity of 2.7 km/s. At its current distance, Beta CrA's brightness is diminished by 0.29 magnitudes due to interstellar dust.

<span class="mw-page-title-main">HD 27245</span> Star in the constellation Camelopardalis

HD 27245, also known as HR 1335 or rarely 25 H. Camelopardalis is a solitary red-hued star located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.4, making it faintly visible to the naked eye. Gaia DR3 Parallax measurements place it approximately 607 light years away from it the Solar System and is drifting further away with a heliocentric radial velocity of 25.2 km/s. At its current distance, HD 27245's brightness is diminished by 0.36 magnitudes due to extinction from interstellar dust. It has an absolute magnitude of −0.27.

<span class="mw-page-title-main">HD 24479</span> Star in the constellation Camelopardalis

HD 24479, also designated as HR 1204, is a solitary, bluish-white hued star located in the northern circumpolar constellation Camelopardalis. The star is visible to the naked eye with an apparent visual magnitude of 5.04. Based on Gaia DR3 parallax measurements, it is located 385 light years from the Sun. However, it is receding with a somewhat constrained heliocentric radial velocity of 4.6 km/s. At its current distance, HD 24479's brightness is diminished by 0.29 magnitudes due to interstellar dust.

Eta<sup>2</sup> Coronae Australis Star in the constellation Corona Austrlis

Eta2 Coronae Australis, Latinized from η2 Coronae Australis, is a solitary star located in the southern constellation of Corona Australis. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.59. Gaia DR3 parallax measurements imply a distance of 770 light years from the Solar System, but it is drifting closer with a radial velocity of −23 km/s. At its current distance Eta2 CrA's brightness is diminished by 0.27 magnitudes due to stellar extinction from interstellar dust and it has an absolute magnitude of −0.24.

<span class="mw-page-title-main">Theta Coronae Australis</span> Star in the constellation Corona Australis

Theta Coronae Australis, Latinized from θ Coronae Australis, is a solitary yellow-hued star located in the southernconstellation Corona Australis. It has an apparent magnitude of 4.61, making it readily visible to the naked eye. Gaia DR3 parallax measurements place it 530 light years away and it is currently drifting closer with a somewhat constrained heliocentric radial velocity of −2.1 km/s. At its current distance, Theta CrA's brightness is diminished by three-tenths of a magnitudes due to interstellar dust. It has an absolute magnitude of −1.54.

<span class="mw-page-title-main">WZ Columbae</span> Star in the constellation of Columba

WZ Columbae, also known as HD 38170, is a solitary, bluish-white hued star located in the southern constellation Columba, the dove. It has an apparent magnitude of 5.28, allowing it to be faintly visible to the naked eye. Based on parallax measurements from the Gaia spacecraft, the object is about 365 light years distant. It appears to be receding from the Solar System, having a heliocentric radial velocity of 36.3 km/s.

<span class="mw-page-title-main">AF Columbae</span> Star in the constellation of Columba

AF Columbae, also known as HD 42682, is a solitary, red hued variable star located in the southern constellation Columba, the dove. It has an apparent magnitude that fluctuates between 5.6 and 5.71. Nevertheless, it is faintly visible to the naked eye. Parallax measurements from the Gaia spacecraft place the star relatively far at a distance of 820 light years. However, it is approaching the Solar System with a poorly constrained radial velocity of −19 km/s.

<span class="mw-page-title-main">8 Leonis Minoris</span> Star in the constellation of Leo Minor

8 Leonis Minoris is a solitary, red hued star located in the northern constellation Leo Minor. It has an apparent magnitude 5.37, making it faintly visible to the naked eye. Based on parallax measurements from the Gaia satellite, the object is estimated to be 492 light years distant. It is receding with a heliocentric radial velocity of 40 km/s. At its current distance, 8 LMi is diminshed by 0.12 magnitudes due to interstellar dust.

<span class="mw-page-title-main">HD 22764</span> Double star; Camelopardalis

HD 22764, also known as HR 1112, is an orange hued star located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.78, allowing it to be faintly visible to the naked eye. The object is located relatively far at a distance of approximately 1,770 light years based on Gaia DR3 parallax measurements but is approaching the Solar System with a heliocentric radial velocity of −12.5 km/s. At its current distance, HD 22764's brightness is diminished by 0.66 magnitudes due to interstellar dust.

<span class="mw-page-title-main">HD 197630</span> Star in the constellation of Microscopium

HD 197630, also known as HR 7933 or rarely 23 G. Microscopii, is a probable astrometric binary located in the southern constellation Microscopium. The visible component is a bluish-white hued star that is faintly visible to the naked eye with an apparent magnitude of 5.47. Based on parallax measurements from the Gaia satellite, the system is estimated to be 328 light years away. However, it is drifting closer with a heliocentric radial velocity of −30 km/s. At its current distance, HD 197630's brightness is diminished by 0.11 magnitudes due to interstellar dust. A 2012 multiplicity survey failed to confirm the velocity variations.

<span class="mw-page-title-main">HD 168592</span> Star in the constellation of Corona Australis

HD 168592, also designated as HR 6862 or rarely 7 G. Coronae Australis, is a solitary star located in the southern constellation Corona Australis. It is faintly visible to the naked eye as an orange-hued star with an apparent magnitude of 5.07. Gaia DR3 parallax measurements place it at a distance of 490 light years and is currently receding with a heliocentric radial velocity of 18 km/s. At its current distance, HD 168592's brightness is diminished by 0.38 magnitudes due to interstellar dust. It has an absolute magnitude of −0.76.

<span class="mw-page-title-main">HD 170642</span> A-type dwarf; Corona Australis

HD 170642, also designated as HR 6942 or rarely 13 G. Coronae Australis, is a single star located in the southern constellation Corona Australis. It is faintly visible to the naked eye as a white hued star with an apparent magnitude of 5.16. The object is located relatively close at a distance of 229 light years based on Hipparcos parallax measurements, but it is approaching the Solar System with a somewhat constrained heliocentric radial velocity of −6 km/s. At its current distance, HD 170642's brightness is diminished by 0.28 magnitudes due to interstellar dust. It has an absolute magnitude of +0.93.

<span class="mw-page-title-main">HD 31134</span> Star in the constellation of Camelopardalis

HD 31134, also designated as HR 1561, is a solitary star located in the northern circumpolar constellation Camelopardalis, the giraffe. It is faintly visible to the naked eye as a white-hued star with an apparent magnitude of 5.74. Gaia DR3 parallax measurements place it 473 light years away. It appears to be approaching the Solar System with a heliocentric radial velocity of −15.1 km/s. At its current distance, HD 31134's brightness is diminished by 0.35 magnitudes due to interstellar dust. It has an absolute magnitude of +0.19.

<span class="mw-page-title-main">V686 Coronae Australis</span> Alpha2 CVn variable; Corona Australis

V686 Coronae Australis is a solitary, bluish-white-hued variable star located in the southern constellation Corona Australis. It has an apparent magnitude that ranges between 5.25 and 5.41, which makes it faintly visible to the naked eye. Gaia DR3 parallax measurements imply a distance of 480 light years and it is slowly receding with a heliocentric radial velocity of 1.3 km/s. At its current distance V686 CrA's average brightness is diminished by 0.35 magnitudes due to extinction from interstellar dust and it has an absolute visual magnitude of −0.24.

<span class="mw-page-title-main">HD 167096</span> Binary star; Corona Australis

HD 167096, also known as HR 6818 or rarely 4 G. Coronae Australis, is a binary star located in the southern constellation Corona Australis. It has an apparent magnitude of 5.45, making it faintly visible to the naked eye. The system is located relatively close at a distance of 224 light years based on Gaia DR3 parallax measurements but is drifting closer with a poorly constrained heliocentric radial velocity of −27 km/s. At its current distance HD 167096's brightness is diminished by three tenths of a magnitudes due to interstellar dust and it has an absolute magnitude of +0.64.

<span class="mw-page-title-main">HD 170521</span> Distant K-type giant; Corona Australis

HD 170521, also known as HR 6937 or rarely 12 G. Coronae Australis, is a solitary star located in the southern constellation Corona Australis. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.69. The object is located relatively far at a distance of approximately 1,500 light years based on Gaia DR3 parallax measurements, and it is receding with a heliocentric radial velocity of 7.2 km/s. At its current distance, HD 170521's brightness is heavily diminished by 0.46 magnitudes due to extinction from interstellar dust and it has an absolute magnitude of −1.90.

<span class="mw-page-title-main">V701 Coronae Australis</span> Delta Scuti variable; Corona Australis

V701 Coronae Australis, or simply V701 CrA, is a solitary, yellowish-white hued variable star located in the southern constellation Corona Australis. It has an average apparent magnitude of 5.72, making it faintly visible to the naked eye under ideal conditions. The object is located relatively close at a distance of 213 light-years based on Gaia DR3 parallax measurements, and it is currently receding with a poorly constrained heliocentric radial velocity of 4 km/s. At its current distance, V701 CrA's brightness is diminished by a quarter of a magnitude due to extinction and it has an absolute magnitude of +1.55.

<span class="mw-page-title-main">18 Sextantis</span> K-type giant star in the constellation Sextans

18 Sextantis, or simply 18 Sex, is a solitary star located in the southern constellation Sextans. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.62. Gaia DR3 parallax measurements imply a distance of 558 light-years and it is slowly receding with a poorly constrained heliocentric radial velocity of approximately 0.2 km/s. At its current distance, 18 Sex's brightness is diminished with an interstellar extinction of two-tenths of a magnitude and it has an absolute magnitude of −0.16.

References

  1. ↑ "Download Data". aavso.org. AAVSO. Retrieved 1 October 2021.
  2. 1 2 3 4 5 6 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.
  3. 1 2 3 Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80–88. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. eISSN   1562-6881. ISSN   1063-7729. S2CID   125853869.
  4. ↑ Szczerba, R.; Siódmiak, N.; Stasińska, G.; Borkowski, J. (29 March 2007). "An evolutionary catalogue of galactic post-AGB and related objects". Astronomy & Astrophysics. 469 (2): 799–806. arXiv: astro-ph/0703717 . Bibcode:2007A&A...469..799S. doi: 10.1051/0004-6361:20067035 . eISSN   1432-0746. ISSN   0004-6361. S2CID   16505186.
  5. ↑ Cannon, Annie Jump; Pickering, Edward Charles (1920). "The Henry Draper catalogue : 12h, 13h, and 14h". Annals of Harvard College Observatory. 95: 1. Bibcode:1920AnHar..95....1C.
  6. 1 2 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". VizieR Online Data Catalog. 2237. Bibcode:2002yCat.2237....0D.
  7. 1 2 Skuljan, L.; Cottrell, P. L. (11 January 1999). "Spectroscopic and photometric observations of the R Coronae Borealis stars S Apodis and RZ Normae throughout their recent declines". Monthly Notices of the Royal Astronomical Society. 302 (2): 341–348. Bibcode:1999MNRAS.302..341S. doi: 10.1046/j.1365-8711.1999.02123.x . eISSN   1365-2966. ISSN   0035-8711. S2CID   120220227.
  8. ↑ Bergeat, J.; Knapik, A.; Rutily, B. (August 2002). "Carbon-rich giants in the HR diagram and their luminosity function". Astronomy & Astrophysics. 390 (3): 967–986. Bibcode:2002A&A...390..967B. doi: 10.1051/0004-6361:20020525 . eISSN   1432-0746. ISSN   0004-6361. S2CID   122775604.
  9. 1 2 3 Kilkenny, D. (1 December 1983). "A possible change in pulsation mode of the R Corona Borealis star, S Apodis". Monthly Notices of the Royal Astronomical Society. 205 (4): 907–912. Bibcode:1983MNRAS.205..907K. doi: 10.1093/mnras/205.4.907 . eISSN   1365-2966. ISSN   0035-8711. S2CID   123036693.
  10. 1 2 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants. Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics. 426 (1): 297–307. arXiv: astro-ph/0404180 . Bibcode:2004A&A...426..297K. doi: 10.1051/0004-6361:20035930 . eISSN   1432-0746. ISSN   0004-6361. S2CID   6077801.
  11. 1 2 McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv: 1208.2037 . Bibcode:2012MNRAS.427..343M. doi: 10.1111/j.1365-2966.2012.21873.x . eISSN   1365-2966. ISSN   0035-8711. S2CID   118665352.
  12. 1 2 Bergeat, J.; Knapik, A.; Rutily, B. (April 2001). "The effective temperatures of carbon-rich stars". Astronomy & Astrophysics. 369 (1): 178–209. Bibcode:2001A&A...369..178B. doi: 10.1051/0004-6361:20010106 . eISSN   1432-0746. ISSN   0004-6361. S2CID   121435880.
  13. ↑ "S Apodis". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved February 25, 2023.
  14. ↑ Pickering, E. C.; Fleming, W. P. (April 1896). "Harvard College Observatory, circular no. 6. New variable stars". The Astrophysical Journal. 3: 296. Bibcode:1896ApJ.....3..296P. doi: 10.1086/140219 . eISSN   1538-4357. ISSN   0004-637X. S2CID   121212070.
  15. ↑ Warner, B. (1 October 1967). "The Hydrogen-Deficient Carbon Stars". Monthly Notices of the Royal Astronomical Society. 137 (2): 119–139. Bibcode:1967MNRAS.137..119W. doi: 10.1093/mnras/137.2.119 . eISSN   1365-2966. ISSN   0035-8711. S2CID   121153173.
  16. ↑ Feast, M. W.; Glass, I. S. (1 March 1973). "Infra-red Photometry of R Coronae Borealis Type Variables and Related Objects". Monthly Notices of the Royal Astronomical Society. 161 (3): 293–303. Bibcode:1973MNRAS.161..293F. doi: 10.1093/mnras/161.3.293 . eISSN   1365-2966. ISSN   0035-8711. S2CID   120889102.
  17. ↑ Zhang, Xianfei; Jeffery, C. Simon (7 September 2012). "Can R Coronae Borealis stars form from the merger of two helium white dwarfs?". Monthly Notices of the Royal Astronomical Society: Letters. 426 (1): L81–L85. arXiv: 1208.3907 . Bibcode:2012MNRAS.426L..81Z. doi: 10.1111/j.1745-3933.2012.01330.x . ISSN   1745-3925. S2CID   118613556.
  18. ↑ Tisserand, P.; Clayton, G. C.; Welch, D. L.; Pilecki, B.; Wyrzykowski, L.; Kilkenny, D. (26 February 2013). "The ongoing pursuit of R Coronae Borealis stars: the ASAS-3 survey strikes again". Astronomy & Astrophysics. 551: A77. arXiv: 1211.2475 . Bibcode:2013A&A...551A..77T. doi: 10.1051/0004-6361/201220713 . eISSN   1432-0746. ISSN   0004-6361. S2CID   59060842.
  19. ↑ García-Hernández, D. A.; Rao, N. Kameswara; Lambert, D. L. (31 July 2013). "Dust Around R Coronae Borealis Stars. II. Infrared Emission Features in an H-poor Environment". The Astrophysical Journal. 773 (2): 107. arXiv: 1307.0294 . Bibcode:2013ApJ...773..107G. doi: 10.1088/0004-637X/773/2/107 . eISSN   1538-4357. ISSN   0004-637X. S2CID   119243395.
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