1 / 30

The Effect of Blue Stragglers on the Integrated Light of Stellar Populations

The Effect of Blue Stragglers on the Integrated Light of Stellar Populations. Bob Rood with the assistance of Ricardo Schiavon and Francesco Ferraro. None!. merger of 2 low-mass stars unevolved, massive star. BSS crucial link between stellar evolution & stellar dynamics.

hovan
Download Presentation

The Effect of Blue Stragglers on the Integrated Light of Stellar Populations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Effect of Blue Stragglers on the Integrated Light of Stellar Populations Bob Rood with the assistance of Ricardo Schiavon and Francesco Ferraro

  2. None!

  3. merger of 2 low-mass stars unevolved, massive star BSS crucial link between stellar evolution & stellar dynamics Blue Straggler Stars BSS have been detected for the first time by Sandage (1953) according to their position in the CMD, BSS should be more massive than normal stars primordial binaries direct collisions

  4. loose GGCs natural habitat low c, low r0 for BSS • high resolution studies • BSSalso in the inner region • of high density GGCs • NGC6397 Auriere et al. 1990 • 47 Tuc Paresce et al. 1991 • M15 Ferraro & Paresce 1993 • Catalogs: • Fusi Pecci et al. 1992 • Sarajedini et al. 1992 • Ferraro, Fusi Pecci, Bellazzini 1995 • Guhathakurta et al. 1994, 1998 • Piotto et al 2004 BSS are a normal population of GGCs, found in each cluster properly observed BSSare more concentrated than RGB stars exceptions: M3, M55 (?), M13,47 Tuc.. Blue Straggler Stars <1990 >1990

  5. UV sensitivity , high resolution systematic studies of hot SPs in the core of high density GGCs The "classical" plane The UV plane HST

  6. M79 with GALEX: FUV - NUV

  7. The very first complete coverage of the entire the cluster extension BSS are more concentrated in the central region BSS are less concentrated in the external region M3 : The first surprise

  8. NBSS/NTOT RBSS= LS/LTOT Is this distribution really “peculiar” & unique ? Blue Straggler Stars: M3 The BSS radial distribution is BIMODAL Highly peaked in the center rapidly decreasing at intermediate radii and finally rising again at larger radii

  9. The BSS radial distribution in 47 Tuc is quite similar to that observed in M3 Is this the “natural” BSS radial distribution? BSS radial distribution

  10. Central peak & the Decreasing at intermediate radii collisional BSS kicked off from the cluster core or BSS generated by primordial binaries Dynamical simulations performed in the case of 47 Tuc (Mapelli et al 2004) showed that a pop. of PB is needed to reproduce the bimodal distribution Mass segregation & dynamical friction The BSS bimodal distributions ? collisional BSS @ center & PB-BSS in the outer regions?

  11. BSS radial distribution v Centauri: NO evidence of mass segregation!!!! The purest population of not-collisional BSS?

  12. Direct comparison of BSS populations

  13. Blue sequences in the UV: direct comparison of BSS populations twin clusters M 3 Log r0 = 3.5 Ms/pc3 Log M =5.8 Ms NBSS = 72 F = 0.28 M 13 Log r0 = 3.4 Ms/pc3 Log M =5.8 Ms NBSS = 16 F = 0.07 ? different primordial binary population ? clusters in different dynamical phases ?

  14. Blue sequences in the UV: direct comparison of BSS populations Log r0 = 5.8 Ms/pc3 NBSS = 129 F = 0.44 F = 1 if only the PC is considered Log r0 = 2.1 Ms/pc3 NBSS = 24 F = 0.92 !!! the largest specific frequency ever observed in one of the lowest density cluster ? different types of BSS ? NGC288 has a large fraction of binaries ! Bellazzini et al. 2002 AJ, 123, 1509

  15. Blue sequences in the UV: direct comparison of BSS populations PCC NBSS = 17 F = 0.16 collapsing NBSS = 129 F = 0.44 – 1.0 ? binaries are preventing core collapse ? are binaries destroyed during the collapse ?

  16. BSS radial distribution v Centauri: NO evidence of mass segregation!!!! The purest population of not-collisional BSS?

  17. Among the GCCs  Cen is the best BSS template NBSS 0.08 NHB NBSS/104L 2

  18. Peterson et al. 2003, ApJ, 588, 299. BSS fit not quite as good as BHB fit at Mg II and below l=2600Å Mg II l<2600Å The real problem: NBSS 7 NRG

  19. In the visible BSS and cool BHB are equivalent

  20. Schiavon et al. 2002 47 Tuc BSS contribute <1% to the integrated light of 47 Tuc

  21. Deng et al. 1999 ApJ, 524, 824 M67 Note: NBSS 4 NHB

  22. Schiavon, et al 2004, ApJ, 127, 1513 M67

  23. Schiavon: BSS greatly increase Balmer line strengths

  24. M67 in the UV (Landesman et al. 1998)

  25. F81 Other BSS Non-BSS

  26. With BSS 2.5 Gyr model Without BSS 4.5 Gyr model

  27. How much has dynamical evolution affected M67?

More Related