18 Sextantis

18 Sextantis
	Location of 18 Sex on the map (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Sextans
Right ascension	10h 10m 55.86074s
Declination	−08° 25′ 06.4527″
Apparent magnitude (V)	5.62±0.01
Characteristics
Spectral type	K2/3 III
U−B color index	+1.42
B−V color index	+1.30
Astrometry
Radial velocity (Rv)	0.2±2.9 km/s
Proper motion (μ)	RA: −0.115 mas/yr ; Dec.: −43.987 mas/yr
Parallax (π)	5.8416 ± 0.0881 mas
Distance	558 ± 8 ly ; (171 ± 3 pc)
Absolute magnitude (MV)	−0.16
Details
Radius	27.3±1.4 R☉
Luminosity	222±12 L☉
Surface gravity (log g)	1.72 cgs
Temperature	4,410±122 K
Metallicity [Fe/H]	−0.31+0.01; −0.00 dex
Rotational velocity (v sin i)	<1.0 km/s
Other designations
	18 Sex, 32 G. Sextantis[13], BD−07°2977, GC 13990, HD 88333, HIP 49865, HR 3996, SAO 137395, TIC 26206896
Database references
SIMBAD	data

18 Sextantis (HD 88333; HR 3996; 32 G. Sextantis), or simply 18 Sex, is a solitary star^[15] 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.^[2] Gaia DR3 parallax measurements imply a distance of 558 light-years^[1] and it is slowly receding with a poorly constrained heliocentric radial velocity of approximately 0.2 km/s.^[5] At its current distance, 18 Sex's brightness is diminished with an interstellar extinction of two-tenths of a magnitude^[16] and it has an absolute magnitude of −0.16.^[6]

18 Sex has a stellar classification of K2/3 III,^[3] indicating that it is an evolved star with the characteristics of a K2 and K3 giant star. At present, it has exhausted hydrogen at its core and it has expanded to 27.3 times the radius of the Sun.^[7] It radiates 222 times the luminosity of the Sun^[8] from its enlarged photosphere at an effective temperature of 4,410 K.^[10] Gaia DR3 models it to be a larger and brighter red giant branch star with a radius of 35.27 R_☉ and a luminosity of 384 L_☉.^[1] 18 Sex is metal deficient with an iron abundance of [Fe/H] = −0.31 or 49% of the Sun's^[11] and it spins too slowly for its projected rotational velocity to be measured accurately, having a velocity lower than 1.0 km/s.^[12]

References

^ ^a ^b ^c ^d ^e ^f 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.
^ ^a ^b 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.
^ ^a ^b Houk, Nancy; Swift, Carrie (1999). Michigan catalogue of two-dimensional spectral types for the HD Stars; vol. 5. Bibcode:1999mctd.book.....H.
^ ^a ^b 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.
^ ^a ^b Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
^ ^a ^b Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
^ ^a ^b 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. arXiv:astro-ph/0404180. Bibcode:2004A&A...426..297K. doi:10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361. S2CID 6077801.
^ ^a ^b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. eISSN 1365-2966. ISSN 0035-8711. S2CID 73594365.
^ ^a ^b Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881. hdl:1721.1/124721. S2CID 166227927.
^ ^a ^b Poggio, E.; Recio-Blanco, A.; Palicio, P. A.; Re Fiorentin, P.; de Laverny, P.; Drimmel, R.; Kordopatis, G.; Lattanzi, M. G.; Schultheis, M.; Spagna, A.; Spitoni, E. (30 September 2022). "The chemical signature of the Galactic spiral arms revealed by Gaia DR3". Astronomy & Astrophysics. 666: L4. arXiv:2206.14849. Bibcode:2022A&A...666L...4P. doi:10.1051/0004-6361/202244361. eISSN 1432-0746. ISSN 0004-6361.
^ ^a ^b 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.
^ 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.
^ "* 18 Sex". SIMBAD. Centre de données astronomiques de Strasbourg.
^ 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.
^ 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.

[GaiaDR3-1] ^ ^a ^b ^c ^d ^e ^f 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.

[Tycho2000-2] 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.

[Houk1999-3] Houk, Nancy; Swift, Carrie (1999). Michigan catalogue of two-dimensional spectral types for the HD Stars; vol. 5. Bibcode:1999mctd.book.....H.

[Johnson1966-4] 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.

[Gontcharov2006-5] Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.

[Anderson2012-6] Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.

[Kervella2004-7] 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. arXiv:astro-ph/0404180. Bibcode:2004A&A...426..297K. doi:10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361. S2CID 6077801.

[GaiaDR2-8] Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.

[McDonald2017-9] McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society. 471 (1): 770–791. arXiv:1706.02208. Bibcode:2017MNRAS.471..770M. doi:10.1093/mnras/stx1433. eISSN 1365-2966. ISSN 0035-8711. S2CID 73594365.

[Stassun2019-10] Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881. hdl:1721.1/124721. S2CID 166227927.

[Poggio2022-11] Poggio, E.; Recio-Blanco, A.; Palicio, P. A.; Re Fiorentin, P.; de Laverny, P.; Drimmel, R.; Kordopatis, G.; Lattanzi, M. G.; Schultheis, M.; Spagna, A.; Spitoni, E. (30 September 2022). "The chemical signature of the Galactic spiral arms revealed by Gaia DR3". Astronomy & Astrophysics. 666: L4. arXiv:2206.14849. Bibcode:2022A&A...666L...4P. doi:10.1051/0004-6361/202244361. eISSN 1432-0746. ISSN 0004-6361.

[De_Medeiros2014-12] 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.

[Gould1879-13] 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.

[SIMBAD-14] "* 18 Sex". SIMBAD. Centre de données astronomiques de Strasbourg.

[Eggleton2008-15] 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.

[Gontcharov2017-16] 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.

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18 Sextantis

See also

References

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