Astronomy:19 Sextantis

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Short description: K-type giant star; Sextans
19 Sextantis
Sextans constellation map.svg
Red circle.svg
Location of 19 Sex on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Sextans
Right ascension  10h 12m 48.36462s[1]
Declination +04° 36′ 52.8378″[1]
Apparent magnitude (V) 5.78±0.01[2]
Characteristics
Evolutionary stage red giant branch[3]
Spectral type K1 III[4] or K0 III[5]
U−B color index +1.11[6]
B−V color index +1.18[6]
Astrometry
Radial velocity (Rv)31.80±0.21[7] km/s
Proper motion (μ) RA: −50.538[1] mas/yr
Dec.: −6.118[1] mas/yr
Parallax (π)6.3184 ± 0.0625[1] mas
Distance516 ± 5 ly
(158 ± 2 pc)
Details
Mass0.88+0.08−0.03[3] M☉
Radius23.13±1.17[8] R☉
Luminosity241+4−5[1] L☉
Temperature4,576±123[9] K
Metallicity [Fe/H]−0.53[10] dex
Rotational velocity (v sin i)2.5±0.8[4] km/s
Age7.94+1.83−0.70[3] Gyr
Other designations
19 Sex, BD+05°2301, GC 14022, HD 88547, HIP 50027, HR 4004, SAO 118164[11]
Database references
SIMBADdata

19 Sextantis (HD 88547; HR 4004; 34 G. Sextantis), or simply 19 Sex, is a solitary star[12] located in the equatorial constellation Sextans. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.78.[2] Gaia DR3 parallax measurements imply a distance of 516 light-years[1] and it is currently receding with a heliocentric radial velocity of 31.8 km/s.[7] At its current distance, 19 Sex's brightness is diminished by an interstellar extinction of 0.17 magnitudes.[13]

19 Sex has a stellar classification of K1 III,[4] indicating that it is an evolved K-type giant star that has ceased hydrogen fusion at it core and it has left the main sequence. It has also been given a slightly hotter class of K0 III.[5] Stellar evolution models from Stock et al. (2018) model it to be a red giant branch star (100% chance)[3] that is currently fusing a hydrogen shell around an inert helium core. It has 88% the mass of the Sun but at the age of 7.94 billion years,[3] it has expanded to 23.13 times the radius of the Sun.[8] It radiates 241 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 4,576 K.[9] 19 Sex is metal deficient with an iron abundance of [Fe/H] = −0.53 or 29.5% of the Sun's[10] and it spins modestly with a projected rotational velocity of 2.5 km/s.[4]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Stock, Stephan; Reffert, Sabine; Quirrenbach, Andreas (August 2018). "Precise radial velocities of giant stars: X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search". Astronomy & Astrophysics 616: A33. doi:10.1051/0004-6361/201833111. ISSN 0004-6361. Bibcode: 2018A&A...616A..33S. 
  4. ↑ 4.0 4.1 4.2 4.3 Henry, Gregory W.; Fekel, Francis C.; Henry, Stephen M.; Hall, Douglas S. (September 2000). "Photometric Variability in a Sample of 187 G and K Giants". The Astrophysical Journal Supplement Series 130 (1): 201–225. doi:10.1086/317346. ISSN 0067-0049. Bibcode: 2000ApJS..130..201H. 
  5. ↑ 5.0 5.1 Adams, Walter S.; Joy, Alfred H.; Humason, Milton L.; Brayton, Ada Margaret (April 1935). "The Spectroscopic Absolute Magnitudes and Parallaxes of 4179 Stars". The Astrophysical Journal 81: 187. doi:10.1086/143628. ISSN 0004-637X. Bibcode: 1935ApJ....81..187A. 
  6. ↑ 6.0 6.1 Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode: 1966CoLPL...4...99J. 
  7. ↑ 7.0 7.1 Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (January 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics 430: 165. doi:10.1051/0004-6361:20041272. Bibcode: 2005A&A...430..165F. 
  8. ↑ 8.0 8.1 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (April 8, 2004). "The angular sizes of dwarf stars and subgiants: Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics 426 (1): 297–307. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode: 2004A&A...426..297K. 
  9. ↑ 9.0 9.1 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  10. ↑ 10.0 10.1 Hekker, S.; Meléndez, J. (December 2007). "Precise radial velocities of giant stars: III. Spectroscopic stellar parameters". Astronomy & Astrophysics 475 (3): 1003–1009. doi:10.1051/0004-6361:20078233. ISSN 0004-6361. Bibcode: 2007A&A...475.1003H. 
  11. ↑ "*19 Sex". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A19+Sex. 
  12. ↑ 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. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode: 2008MNRAS.389..869E. 
  13. ↑ 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. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
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