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Open cluster remnant

January 01, 1970

In astronomy, an open cluster remnant (OCR) is the final stage in the evolution of an open star cluster.

Theory edit

Viktor Ambartsumian (1938) and Lyman Spitzer (1940) showed that, from a theoretical point of view, it was impossible for a star cluster to evaporate completely; furthermore, Spitzer pointed out two possible final results for the evolution of a star cluster: evaporation provokes physical collisions between stars, or evaporation proceeds until a stable binary or higher multiplicity system is produced.

Observations edit

Using objective-prism plates, Lodén (1987, 1988, 1993) has investigated the possible population of open cluster remnants in our Galaxy under the assumption that the stars in these clusters should have similar luminosity and spectral type. He found that about 30% of the objects in his sample could be catalogued as a possible type of cluster remnant. The membership for these objects is ≥ 15. The typical age of these systems is about 150 Myr with a range of 50-200 Myr. They show a significant density of binaries and a large number of optical binaries. The stars of these OCRs have a trend to be massive and hence early-type (A-F) stars although this observational method includes a noticeable selection effect because bright early-type spectra are easier to detect than fainter and later ones. In fact, almost no stars with spectral type later than F appear among his objects. On the other hand, his results were not fully conclusive because there are known regions in the sky with many stars of the same spectral type but in which it is difficult to find two stars with the same proper motions or radial velocity. A striking example of this fact is Upgren 1; initially, it was suggested that this small group of seven F stars was the remnant of an old cluster (Upgren & Rubin 1965) but later, Gatewood et al. (1988) concluded that Upgren 1 is only a chance alignment of F stars resulting from the close passage of members of two dynamically different sets of stars. Very recently, Stefanik et al. (1997) have shown that one of the sets is formed by 5 stars including a long-period binary and an unusual triple system.

Simulations edit

Regarding numerical simulations, for systems with some 25 to 250 stars, von Hoerner (1960, 1963), Aarseth (1968) and van Albada (1968) suggested that the final outcome of the evolution of an open cluster is one or more tightly bound binaries (or even a hierarchical triple system). Van Albada pointed out several observational candidates (σ Ori, ADS 12696, ρ Oph, 1 Cas, 8 Lac and 67 Oph) as being OCRs and Wielen (1975) indicated another one, the Ursa Major moving group (Collinder 285).

References edit

  • Aarseth, S. J.; 1968, Bull. Astron. Ser., 3, 3, 105
  • van Albada, T. S.; 1968, Bull. Astron. Inst. Neth., 19, 479
  • Ambartsumian, V. A.; 1938, Ann. Len. State Univ., # 22, 4, 19 (English translation in: Dynamics of Star Clusters, eds. J. Goodman, P. Hut, (Dordrecht: Reidel) p. 521)
  • Gatewood, G.; De Jonge, J. K.; Castelaz, M.; et al., 1988, ApJ, 332, 917
  • von Hoerner, S.; 1960, Z. Astrophys., 50, 184
  • von Hoerner, S.; 1963, Z. Astrophys., 57, 47
  • Lodén, L. O.; 1987, Ir. Astron. J., 18, 95
  • Lodén, L. O.; 1988, A&SS, 142, 177
  • Lodén, L. O.; 1993, A&SS, 199, 165
  • Spitzer, L.; 1940, MNRAS, 100, 397
  • Stefanik, R. P.; Caruso, J. R.; Torres, G.; Jha, S.; Latham, D. W.; 1997, Baltic Astronomy, 6, 137
  • Upgren, A. R.; Rubin V. C.; 1965, PASP, 77, 355
  • Wielen, R.; 1975, in: Dynamics of Stellar Systems, ed. A. Hayli, (Dordrecht: Reidel) p. 97
Further reading
  • Bica, E.; Santiago, B. X.; Dutra, C. M.; Dottori, H.; de Oliveira, M. R.; Pavani D., 2001, A&A, 366, 827-833 [1]
  • Carraro, G.; 2002, A&A, 385, 471-478 [2]
  • Carraro, G.; de la Fuente Marcos, Raúl; Villanova, S.; Moni Bidin, C.; de la Fuente Marcos, Carlos; Baumgardt, H.; Solivella, G.; 2007, A&A, 466, 931-941 [3]
  • Carraro, G.; 2006, Bulletin of the Astronomical Society of India, 34, 153-162 [4]
  • de la Fuente Marcos, Raúl; 1998, A&A, 333, L27-L30 [5]
  • de la Fuente Marcos, Raúl; de la Fuente Marcos, Carlos; Moni Bidin, C.; Carraro, G.; Costa, E.; 2013, MNRAS, 434, 194-208 [6]
  • Kouwenhoven, M. B. N.; Goodwin, S. P.; Parker, R. J.; Davies, M. B.; Malmberg, D.; Kroupa, P.; 2010, MNRAS, 404, 1835-1848 [7]
  • Moni Bidin, C.; de la Fuente Marcos, Raúl; de la Fuente Marcos, Carlos; Carraro, G.; 2010, A&A, 510, A44 [8]
  • Pavani, D. B.; Bica, E.; 2007, A&A, 468, 139-150 [9]
  • Pavani, D. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.; 2003, A&A, 399, 113-120 [10]
  • Pavani, D. B.; Bica, E.; Dutra, C. M.; Dottori, H.; Santiago, B. X.; Carranza, G.; Díaz, R. J.; 2001, A&A, 374, 554-563 [11]
  • Pavani, D. B.; Kerber, L. O.; Bica, E.; Maciel, W. J.; 2011, MNRAS, 412, 1611-1626 [12]
  • Villanova, S., Carraro, G.; de la Fuente Marcos, Raúl; Stagni, R.; 2004, A&A, 428, 67-77 [13]

January 01, 1970
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This article includes a list of references related reading or external links but its sources remain unclear because it lacks inline citations Please help improve this article by introducing more precise citations May 2014 Learn how and when to remove this message In astronomy an open cluster remnant OCR is the final stage in the evolution of an open star cluster Contents 1 Theory 2 Observations 3 Simulations 4 ReferencesTheory editViktor Ambartsumian 1938 and Lyman Spitzer 1940 showed that from a theoretical point of view it was impossible for a star cluster to evaporate completely furthermore Spitzer pointed out two possible final results for the evolution of a star cluster evaporation provokes physical collisions between stars or evaporation proceeds until a stable binary or higher multiplicity system is produced Observations editUsing objective prism plates Loden 1987 1988 1993 has investigated the possible population of open cluster remnants in our Galaxy under the assumption that the stars in these clusters should have similar luminosity and spectral type He found that about 30 of the objects in his sample could be catalogued as a possible type of cluster remnant The membership for these objects is 15 The typical age of these systems is about 150 Myr with a range of 50 200 Myr They show a significant density of binaries and a large number of optical binaries The stars of these OCRs have a trend to be massive and hence early type A F stars although this observational method includes a noticeable selection effect because bright early type spectra are easier to detect than fainter and later ones In fact almost no stars with spectral type later than F appear among his objects On the other hand his results were not fully conclusive because there are known regions in the sky with many stars of the same spectral type but in which it is difficult to find two stars with the same proper motions or radial velocity A striking example of this fact is Upgren 1 initially it was suggested that this small group of seven F stars was the remnant of an old cluster Upgren amp Rubin 1965 but later Gatewood et al 1988 concluded that Upgren 1 is only a chance alignment of F stars resulting from the close passage of members of two dynamically different sets of stars Very recently Stefanik et al 1997 have shown that one of the sets is formed by 5 stars including a long period binary and an unusual triple system Simulations editRegarding numerical simulations for systems with some 25 to 250 stars von Hoerner 1960 1963 Aarseth 1968 and van Albada 1968 suggested that the final outcome of the evolution of an open cluster is one or more tightly bound binaries or even a hierarchical triple system Van Albada pointed out several observational candidates s Ori ADS 12696 r Oph 1 Cas 8 Lac and 67 Oph as being OCRs and Wielen 1975 indicated another one the Ursa Major moving group Collinder 285 References editAarseth S J 1968 Bull Astron Ser 3 3 105 van Albada T S 1968 Bull Astron Inst Neth 19 479 Ambartsumian V A 1938 Ann Len State Univ 22 4 19 English translation in Dynamics of Star Clusters eds J Goodman P Hut Dordrecht Reidel p 521 Gatewood G De Jonge J K Castelaz M et al 1988 ApJ 332 917 von Hoerner S 1960 Z Astrophys 50 184 von Hoerner S 1963 Z Astrophys 57 47 Loden L O 1987 Ir Astron J 18 95 Loden L O 1988 A amp SS 142 177 Loden L O 1993 A amp SS 199 165 Spitzer L 1940 MNRAS 100 397 Stefanik R P Caruso J R Torres G Jha S Latham D W 1997 Baltic Astronomy 6 137 Upgren A R Rubin V C 1965 PASP 77 355 Wielen R 1975 in Dynamics of Stellar Systems ed A Hayli Dordrecht Reidel p 97 Further reading Bica E Santiago B X Dutra C M Dottori H de Oliveira M R Pavani D 2001 A amp A 366 827 833 1 Carraro G 2002 A amp A 385 471 478 2 Carraro G de la Fuente Marcos Raul Villanova S Moni Bidin C de la Fuente Marcos Carlos Baumgardt H Solivella G 2007 A amp A 466 931 941 3 Carraro G 2006 Bulletin of the Astronomical Society of India 34 153 162 4 de la Fuente Marcos Raul 1998 A amp A 333 L27 L30 5 de la Fuente Marcos Raul de la Fuente Marcos Carlos Moni Bidin C Carraro G Costa E 2013 MNRAS 434 194 208 6 Kouwenhoven M B N Goodwin S P Parker R J Davies M B Malmberg D Kroupa P 2010 MNRAS 404 1835 1848 7 Moni Bidin C de la Fuente Marcos Raul de la Fuente Marcos Carlos Carraro G 2010 A amp A 510 A44 8 Pavani D B Bica E 2007 A amp A 468 139 150 9 Pavani D B Bica E Ahumada A V Claria J J 2003 A amp A 399 113 120 10 Pavani D B Bica E Dutra C M Dottori H Santiago B X Carranza G Diaz R J 2001 A amp A 374 554 563 11 Pavani D B Kerber L O Bica E Maciel W J 2011 MNRAS 412 1611 1626 12 Villanova S Carraro G de la Fuente Marcos Raul Stagni R 2004 A amp A 428 67 77 13 Retrieved from https en wikipedia org w index php title Open cluster remnant amp oldid 776148327, wikipedia, wiki, book, books, library,

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