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Scorpius–Centaurus association

(Redirected from Sco OB2)

The Scorpius–Centaurus association (sometimes called Sco–Cen or Sco OB2) is the nearest OB association to the Sun. This stellar association is composed of three subgroups (Upper Scorpius, Upper Centaurus–Lupus, and Lower Centaurus–Crux) and its distance is about 130 parsecs or 420 light-years.[1] Analysis using improved Hipparcos data has brought the number of known members to 436. The cluster shows a continuous spread of stars with no apparent need for subclassification.[2]

Map of the area containing stars of the Scorpius–Centaurus association
Main associations of the Solar antapex half of the galactic plane, with Sco-Cen on the left

The Sco–Cen subgroups range in age from 11 million years (Upper Scorpius)[3] to roughly 15 million years (Upper Centaurus–Lupus and Lower Centaurus–Crux). Many of the bright stars in the constellations Scorpius, Lupus, Centaurus, and Crux are members of the Sco–Cen association, including Antares (the most massive member of Upper Scorpius), and most of the stars in the Southern Cross.[4] Hundreds of stars have been identified as members of Sco-Cen, with masses ranging from roughly 15 solar masses (Antares) down to below the hydrogen-burning limit (i.e. brown dwarfs),[5] and the total stellar population in each of the three subgroups is probably of the order 1000–2000.[6] The Sco–Cen OB association appears to be the most pronounced part of a large complex of recent (<20 million years) and ongoing star-formation. The complex contains several star-forming molecular clouds in Sco–Cen's immediate vicinity—the Rho Oph, Pipe Nebula, Barnard 68, Chamaeleon, Lupus, Corona Australis, and Coalsack cloud complexes (all at distances of ~120-200 parsecs), and several less populous, young stellar groups on the periphery of Sco–Cen, including the ~3–5 million-year-old Epsilon Chamaeleontis group, ~7 million-year-old Eta Chamaeleontis moving group, ~8 million-year-old TW Hydrae association, ~12 million-year-old Beta Pictoris moving group, and possibly the ~30–50 million-year-old IC 2602 open cluster.[4]

The stellar members of the Sco–Cen association have convergent proper motions of approximately 0.02–0.04 arcseconds per year, indicative that the stars have nearly parallel velocity vectors, moving at about 20 km/s with respect to the Sun. The dispersion of the velocities within the subgroups are only of order 1–2 km/s,[7] and the group is most likely gravitationally unbound. Several supernovae have exploded in Sco–Cen over the past 15 million years, leaving a network of expanding gas superbubbles around the group,[8] including the Loop I Bubble.

To explain the presence of radioactive 60Fe in deep ocean ferromanganese crusts and in biogenic magnetite crystals within Pacific Ocean sediments[9] it has been hypothesized that a nearby supernova, possibly a member of Sco–Cen, exploded in the Sun's vicinity roughly 3 million years ago,[10] causing the Pliocene–Pleistocene boundary marine extinction.[11] However, other findings cite the distance at which this supernova occurred at more than 100 parsec, maintaining that it is not likely not to have contributed to this extinction through the mechanism of what is known as the ultra-violet B (UV-B) catastrophe.[9][12] In 2019, researchers found interstellar iron in Antarctica which they relate to the Local Interstellar Cloud, which might have been formed near the Sco-Cen association.[13]

Close up on the Orion Arm, with major stellar associations (yellow), nebulae (red) and dark nebulae (grey) coreward from the Local Bubble with Sco-Cen.

In December 2021, around 70 new rogue planets were discovered in the Upper Scorpius association.[14]

The subgroups of the Scorpius-Centaurus association contains the youngest[15] transiting exoplanets: K2-33 b (11 Myrs),[16] TOI-1227 b (11 Myrs)[17] and HIP 67522 b (17 Myrs).[18] It also contains directly imaged exoplanets such as UScoCTIO 108 b and the PDS 70 system.[19]

Notable stars

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See also

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References

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  1. ^ Melnik, A. M.; Dambis, A. K. (2020). "Distance scale for high-luminosity stars in OB associations and in field with Gaia DR2. Spurious systematic motions". Astrophysics and Space Science. 365 (7): 112. arXiv:2006.14649. Bibcode:2020Ap&SS.365..112M. doi:10.1007/s10509-020-03827-0. S2CID 220128144.
  2. ^ Rizzuto, Aaron; Ireland, Michael; Robertson, J. G. (October 2011), "Multidimensional Bayesian membership analysis of the Sco OB2 moving group", Monthly Notices of the Royal Astronomical Society, 416 (4): 3108–17, arXiv:1106.2857, Bibcode:2011MNRAS.416.3108R, doi:10.1111/j.1365-2966.2011.19256.x, S2CID 54510608.
  3. ^ Mark J. Pecaut; Eric E. Mamajek & Eric J. Bubar (February 2012). "A Revised Age for Upper Scorpius and the Star Formation History among the F-type Members of the Scorpius–Centaurus OB Association". Astrophysical Journal. 746 (2): 154. arXiv:1112.1695. Bibcode:2012ApJ...746..154P. doi:10.1088/0004-637X/746/2/154. S2CID 118461108.
  4. ^ a b c Preibisch, T.; Mamajek, E. (2009). "The Nearest OB Association: Scorpius-Centaurus (Sco OB2)". Handbook of Star-Forming Regions. 2: 0. arXiv:0809.0407. Bibcode:2008hsf2.book..235P.
  5. ^ Preibisch, T.; et al. (2002). "Exploring the Full Stellar Population of the Upper Scorpius OB Association". Astronomical Journal. 124 (1): 404–416. Bibcode:2002AJ....124..404P. doi:10.1086/341174.
  6. ^ Mamajek, E.E.; Meyer, M.R. & Liebert, James (2002). "Post-T Tauri Stars in the Nearest OB Association". Astronomical Journal. 124 (3): 1670–1694. arXiv:astro-ph/0205417. Bibcode:2002AJ....124.1670M. doi:10.1086/341952. S2CID 16855894.
  7. ^ Madsen, S.; et al. (2002). "Astrometric radial velocities. III. Hipparcos measurements of nearby star clusters and associations". Astronomy & Astrophysics. 381 (2): 446–463. arXiv:astro-ph/0110617. Bibcode:2002A&A...381..446M. doi:10.1051/0004-6361:20011458. S2CID 17596452.
  8. ^ de Geus, E.J. (1992). "Interaction of Stars and Interstellar Matter in Scorpio Centaurus". Astronomy & Astrophysics. 262: 258–270. Bibcode:1992A&A...262..258D.
  9. ^ a b Ludwig, Peter; et al. (2016). "Time-resolved 2-million-year-old supernova activity discovered in Earth's microfossil record". Proceedings of the National Academy of Sciences. 113 (33): 9232–9237. arXiv:1710.09573. Bibcode:2016PNAS..113.9232L. doi:10.1073/pnas.1601040113. ISSN 0027-8424. PMC 4995991. PMID 27503888.
  10. ^ Fields, Brian D.; Hochmuth, Kathrin A.; Ellis, John (2005). "Deep-Ocean Crusts as Telescopes: Using Live Radioisotopes to Probe Supernova Nucleosynthesis". Astrophys. J. 621 (2): 902–07. arXiv:astro-ph/0410525. Bibcode:2005ApJ...621..902F. doi:10.1086/427797. S2CID 17932224.
  11. ^ Benítez, N.; Maíz-Apellániz, J.; Canelles M. (2005). "Evidence for nearby supernova explosions". Phys. Rev. Lett. 88 (8): 081101. arXiv:astro-ph/0201018. Bibcode:2002PhRvL..88h1101B. doi:10.1103/physrevlett.88.081101. PMID 11863949. S2CID 41229823.
  12. ^ Cockell, CS (1999). "Crises and extinction in the fossil record—A role for ultraviolet radiation?". Paleobiology. 25 (2): 212–225. Bibcode:1999Pbio...25..212C. doi:10.1017/S0094837300026518. S2CID 132108580.
  13. ^ Koll, D.; et., al. (2019). "Interstellar 60Fe in Antarctica". Physical Review Letters. 123 (7): 072701. Bibcode:2019PhRvL.123g2701K. doi:10.1103/PhysRevLett.123.072701. hdl:1885/298253. PMID 31491090. S2CID 201868513.
  14. ^ "ESO telescopes help uncover largest group of rogue planets yet". European Southern Observatory. 22 December 2021. Retrieved 22 December 2021. See also attached research paper.
  15. ^ "Planetary Systems". exoplanetarchive.ipac.caltech.edu. Retrieved 2022-09-12. as of September 2022
  16. ^ Mann, Andrew W.; Newton, Elisabeth R.; Rizzuto, Aaron C.; Irwin, Jonathan; Feiden, Gregory A.; Gaidos, Eric; Mace, Gregory N.; Kraus, Adam L.; James, David J.; Ansdell, Megan; Charbonneau, David; Covey, Kevin R.; Ireland, Michael J.; Jaffe, Daniel T.; Johnson, Marshall C. (2016-09-01). "Zodiacal Exoplanets in Time (ZEIT). III. A Short-period Planet Orbiting a Pre-main-sequence Star in the Upper Scorpius OB Association". The Astronomical Journal. 152 (3): 61. arXiv:1604.06165. Bibcode:2016AJ....152...61M. doi:10.3847/0004-6256/152/3/61. ISSN 0004-6256. S2CID 6552081.
  17. ^ Mann, Andrew W.; Wood, Mackenna L.; Schmidt, Stephen P.; Barber, Madyson G.; Owen, James E.; Tofflemire, Benjamin M.; Newton, Elisabeth R.; Mamajek, Eric E.; Bush, Jonathan L.; Mace, Gregory N.; Kraus, Adam L.; Thao, Pa Chia; Vanderburg, Andrew; Llama, Joe; Johns-Krull, Christopher M. (2022-04-01). "TESS Hunt for Young and Maturing Exoplanets (THYME). VI. An 11 Myr Giant Planet Transiting a Very-low-mass Star in Lower Centaurus Crux". The Astronomical Journal. 163 (4): 156. arXiv:2110.09531. Bibcode:2022AJ....163..156M. doi:10.3847/1538-3881/ac511d. ISSN 0004-6256.
  18. ^ Rizzuto, Aaron C.; Newton, Elisabeth R.; Mann, Andrew W.; Tofflemire, Benjamin M.; Vanderburg, Andrew; Kraus, Adam L.; Wood, Mackenna L.; Quinn, Samuel N.; Zhou, George; Thao, Pa Chia; Law, Nicholas M.; Ziegler, Carl; Briceño, César (2020-07-01). "TESS Hunt for Young and Maturing Exoplanets (THYME). II. A 17 Myr Old Transiting Hot Jupiter in the Sco-Cen Association". The Astronomical Journal. 160 (1): 33. arXiv:2005.00013. Bibcode:2020AJ....160...33R. doi:10.3847/1538-3881/ab94b7. ISSN 0004-6256.
  19. ^ Keppler, M.; Benisty, M.; Müller, A.; Henning, Th.; van Boekel, R.; Cantalloube, F.; Ginski, C.; van Holstein, R. G.; Maire, A. -L.; Pohl, A.; Samland, M.; Avenhaus, H.; Baudino, J. -L.; Boccaletti, A.; de Boer, J. (2018-09-01). "Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70". Astronomy and Astrophysics. 617: A44. arXiv:1806.11568. Bibcode:2018A&A...617A..44K. doi:10.1051/0004-6361/201832957. ISSN 0004-6361.
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