HD 162826

HD 162826 (HR 6669, HIP 87382)[14] is a star in the constellation Hercules. It is about 110 light-years (34 parsecs) away from Earth.[1] With an apparent magnitude of 6.55,[2] the star can be found with binoculars or a low-power telescope by reference to nearby Vega in the constellation Lyra.[15]

HD 162826
HD 162826 is located in the constellation Pavo.
HD 162826 is located in the constellation Pavo.
HD 162826
Location of HD 162826 in the constellation Hercules

Observation data
Epoch J2000      Equinox J2000
Constellation Hercules
Right ascension 17h 51m 14.02244s[1]
Declination +40° 04′ 20.8772″[1]
Apparent magnitude (V) 6.55±0.01[2]
Characteristics
Spectral type F8 V[3][4]
U−B color index +0.04[2]
B−V color index +0.52[2]
Astrometry
Radial velocity (Rv)1.9±0.1[5] km/s
Proper motion (μ) RA: −16.864 mas/yr[1]
Dec.: +9.833 mas/yr[1]
Parallax (π)30.068 ± 0.0646 mas[1]
Distance108.5 ± 0.2 ly
(33.26 ± 0.07 pc)
Absolute magnitude (MV)+3.92[6]
Details
Mass1.17[7] M☉
Radius1.32±0.04[8] R☉
Luminosity2.27[9] L☉
Surface gravity (log g)4.28+0.02
−0.03[8] cgs
Temperature6,158±9[10] K
Metallicity [Fe/H]+0.02±0.04[11] dex
Rotational velocity (v sin i)5[12][13] km/s
Age3.88[7] Gyr
Other designations
AG+40°1628, BD+40°3225, GC 24279, HD 162826, HIP 87382, HR 6669, SAO 47009, TYC 3093-1946-1, 2MASS J17511402+4004208
Database references
SIMBADdata

The star is considered to be a stellar sibling of the Sun and is the first such sibling to be discovered.[16] Solar siblings are those stars that formed from the same gas cloud and in the same star cluster; the term was introduced in 2009.[17][18] No planets have been detected orbiting HD 162826, but due to its metallicity, it is likely to harbor terrestrial planets; the star's spectra had been under observation previously.[19]

In November 2018, a second potential solar twin was announced, HD 186302, an 8th magnitude star in the Pavo constellation.[20]

Origin

In May 2014, astronomers at the University of Texas at Austin announced that HD 162826 is "almost certainly" one of what may be thousands of siblings of the Sun, emerging from the same stellar nursery some 4.5 billion years ago. This conclusion was reached by determining it has the same chemical composition as the Sun, including rare elements such as barium and yttrium, and by determining its orbit and projecting backward its revolutions about the Galactic Center.[21][22][23]

The cluster in which HD 162826 and the Sun formed is believed to have been an open cluster, permitting the stars to scatter widely over time. The stars in this cluster were not too closely packed during their formation to disrupt planetary disk development, but were not so far apart as to prevent the seeding of Earth with radioactive elements produced by a nearby supernova.[24]

The discovery of a first solar sibling by searching for specific rare elements may make it easier to identify other siblings in the future.[25] However, HD 162826 is probably the nearest solar sibling, because others would have been identified first if they had been closer to the Sun. It had not been expected that even one sibling would be found at this relatively short distance; the study that identified this star worked on a dataset of only 100,000 stars, to prepare to receive data about billions of stars expected from the Gaia Space Telescope in five to ten years.[26]

Possible planets and habitability

HD 162826 has no known planets. The current state of knowledge excludes hot Jupiters and suggests that a more distant "Jupiter" is unlikely,[27] but terrestrial planets are possible.[22]

Lead researcher Ivan Ramirez explained the significance of finding solar siblings:

"We want to know where we were born. If we can figure out in what part of the galaxy the Sun formed, we can constrain conditions on the early Solar System. That could help us understand why we are here."[28]

He suggested a "small, but not zero" chance that planets with life might orbit solar sibling stars, because during the frequent collisions during planetary formation material might have travelled from one system to another. He said the siblings might be "key candidates" in the search for extraterrestrial life.[28] A scenario for transfer of life by this means might require life or a precursor molecule to be shielded from radiation for millions of years, dormant within an outgoing chunk of planetary debris a meter or more in diameter that is produced by a meteorite impact, until this new meteorite impacts on a different planet. Such an unlikely event might have transferred life from another planet to Earth or vice versa.[29]

See also

References
  1. 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. Oja, T. (August 1991). "UBV photometry of stars whose positions are accurately known. VI". Astronomy and Astrophysics Supplement Series. 89: 415. Bibcode:1991A&AS...89..415O. ISSN 0365-0138.
  3. 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. Bibcode:1935ApJ....81..187A. doi:10.1086/143628. eISSN 1538-4357. ISSN 0004-637X.
  4. Gray, R. O.; Napier, M. G.; Winkler, L. I. (April 2001). "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars". The Astronomical Journal. 121 (4): 2148–2158. Bibcode:2001AJ....121.2148G. doi:10.1086/319956. ISSN 0004-6256.
  5. Nidever, David L.; Marcy, Geoffrey W.; Butler, R. Paul; Fischer, Debra A.; Vogt, Steven S. (August 2002). "Radial Velocities for 889 Late‐Type Stars". The Astrophysical Journal Supplement Series. 141 (2): 503–522. arXiv:astro-ph/0112477. Bibcode:2002ApJS..141..503N. doi:10.1086/340570. eISSN 1538-4365. ISSN 0067-0049.
  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.
  7. Dotter, Aaron; Chaboyer, Brian; Jevremović, Darko; Kostov, Veselin; Baron, E.; Ferguson, Jason W. (September 2008). "The Dartmouth Stellar Evolution Database". The Astrophysical Journal Supplement Series. 178 (1): 89–101. arXiv:0804.4473. Bibcode:2008ApJS..178...89D. doi:10.1086/589654. eISSN 1538-4365. ISSN 0067-0049.
  8. Takeda, Genya; Ford, Eric B.; Sills, Alison; Rasio, Frederic A.; Fischer, Debra A.; Valenti, Jeff A. (February 2007). "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog". The Astrophysical Journal Supplement Series. 168 (2): 297–318. arXiv:astro-ph/0607235. Bibcode:2007ApJS..168..297T. doi:10.1086/509763. eISSN 1538-4365. ISSN 0067-0049.
  9. 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.
  10. Muñoz Bermejo, J.; Asensio Ramos, A.; Allende Prieto, C. (May 2013). "A PCA approach to stellar effective temperatures". Astronomy & Astrophysics. 553: A95. arXiv:1303.7218. Bibcode:2013A&A...553A..95M. doi:10.1051/0004-6361/201220961. eISSN 1432-0746. ISSN 0004-6361.
  11. Aguilera-Gómez, Claudia; Ramírez, Iván; Chanamé, Julio (June 2018). "Lithium abundance patterns of late-F stars: an in-depth analysis of the lithium desert". Astronomy & Astrophysics. 614: A55. arXiv:1803.05922. Bibcode:2018A&A...614A..55A. doi:10.1051/0004-6361/201732209. eISSN 1432-0746. ISSN 0004-6361.
  12. Wilson, O. C. (May 1966). "Stellar Convection Zones, Chromospheres, and Rotation". The Astrophysical Journal. 144: 695. Bibcode:1966ApJ...144..695W. doi:10.1086/148649. eISSN 1538-4357. ISSN 0004-637X.
  13. Kraft, Robert P. (November 1967). "Studies of Stellar Rotation. V. The Dependence of Rotation on Age among Solar-Type Stars". The Astrophysical Journal. 150: 551. Bibcode:1967ApJ...150..551K. doi:10.1086/149359. eISSN 1538-4357. ISSN 0004-637X.
  14. "HD 162826". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 9, 2014.
  15. Saltarin, Alexander (May 10, 2014). "Meet HD 162826, the sister star of our Sun". Tech Times. Retrieved November 11, 2014.
  16. "Astronomers find Sun's 'long-lost brother,' pave way for family reunion". Science Daily. May 10, 2014. Retrieved May 13, 2014.
  17. Zwart, S. Portegies (November 2009). "The long-lost siblings of the Sun". Scientific American. 301 (5): 40–47. Bibcode:2009SciAm.301e..40P. doi:10.1038/scientificamerican1109-40. PMID 19873903. Retrieved November 11, 2014.
  18. Portegies Zwart, S. (April 2009). "The Lost Siblings of the Sun". The Astrophysical Journal Letters. 696 (1): L13–L16. arXiv:0903.0237. Bibcode:2009ApJ...696L..13P. doi:10.1088/0004-637X/696/1/L13. S2CID 17168366.
  19. González, G.; et al. (December 8, 2009). "Parent stars of extrasolar planets – X. Lithium abundances and v sin i revisited". MNRAS. 403 (3): 1368–1380. arXiv:0912.1621. Bibcode:2010MNRAS.403.1368G. doi:10.1111/j.1365-2966.2009.16195.x. S2CID 118520284.
  20. King, Bob P. (2018-11-24). Did Astronomers Just Find The Sun’s Sister? Astro Bob, Duluth News Tribune, 24 November 2018. Originally retrieved from http://astrobob.areavoices.com/2018/11/24/did-astronomers-just-find-the-suns-sister. Archived on 2018-11-25 at https://web.archive.org/web/20181125115534/http://astrobob.areavoices.com/2018/11/24/did-astronomers-just-find-the-suns-sister/.
  21. Garber, Megan (May 8, 2014). "Our Sun Has a Sister". The Atlantic. Retrieved May 9, 2014.
  22. Klotz, Irene (May 9, 2014). "Our Sun's Long Lost Stellar 'Sister' Found". Discovery News. Archived from the original on May 7, 2015. Retrieved May 10, 2014.
  23. Ramirez, I.; et al. (2014). "Elemental Abundances of Solar Sibling Candidates" (PDF). The Astrophysical Journal. 787 (2): 154. arXiv:1405.1723. Bibcode:2014ApJ...787..154R. doi:10.1088/0004-637X/787/2/154. hdl:2152/35056. S2CID 118441281. Archived from the original (PDF) on 2014-05-12.
  24. Spotts, Pete (May 9, 2014). "Scientists make a positive ID: Nearby star is a 'sibling' of our Sun". The Christian Science Monitor. Retrieved May 10, 2014.
  25. "Astronomers Find Sun's Sibling 'HD 162826'". Nature World News. May 9, 2014.
  26. Netburn, Deborah (May 9, 2014). "Our Sun's long-lost stellar sibling found at last, astronomers say". Los Angeles Times.
  27. PTI (May 10, 2014). "First solar 'sibling' discovered". India Times.
  28. "Astronomers Find Sun's Long Lost Brother". University of Texas at Austin. May 8, 2014. Archived from the original on May 10, 2014. Retrieved May 9, 2014.
  29. Gates, Sara (2014-05-10). "Sun's 'Long-Lost Sibling' Star Identified By Texas Astronomers". The Huffington Post.
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