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M5 = NGC 5904 ( nearest “intermediate-metallicity” globular cluster

M5 = NGC 5904 ( nearest “intermediate-metallicity” globular cluster accessible from a northern hemisphere site ) Harris (2003, Feb version) 7.5kpc from the Sun, 6.2kpc from gal. centre [Fe/H] = -1.2 7 (= -1.40 in ZW84) E(B-V) = 0.03, high galactic latitude (+46.8 deg)

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M5 = NGC 5904 ( nearest “intermediate-metallicity” globular cluster

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  1. M5 = NGC 5904 (nearest “intermediate-metallicity” globular cluster • accessible from a northern hemisphere site) • Harris (2003, Feb version) • 7.5kpc from the Sun, 6.2kpc from gal. centre • [Fe/H] = -1.27 (= -1.40 in ZW84) • E(B-V) = 0.03, high galactic latitude (+46.8 deg) • HB index (B-R)/(B+V+R) = 0.31, c = 1.83 • By Ivans, Kraft, Sneden, Smith, Rich, Shetrone (2001) vs. M4 • - 36 luminous giants and AGB stars • By Cohen, Briley, & Stetson (2002) vs. M71 (nearest from n. h.) • - C & N variations at the base of the RGB • By Ramirez & Cohen (2003) vs. M71 (c.f. 47 Tuc) • - 25 stars covering a wide range in luminosity

  2. CMD of M5 by Sohn & Lee (2000) -metallicity via photometry -HB morphology

  3. B:V:R = 75:95:56 (B-R)/(B+V+R)=0.08 B:V:R = 92:40:32 (B-R)/(B+V+R)=0.37

  4. Ivans et al. (2001) - 36 luminous giants and AGB stars CMDof M5, showing thepositions of programstars on the AGBand RGB. Symbols givenat lower right correspondto the observatory andresolution used for eachobservation.

  5. Ivans et al. (2001) <[Fe/H]> = -1.21 based on FeII, adopting non-LTE precepts <[Fe/H]> = -1.34 based on FeI e.g., M4, <[Fe/H]> = -1.08, redeterminedfrom -1.18

  6. Ivans et al. (2001) Boxplot of the M5giant star element abundances. For each abundance ratiothe "box" contains themiddle 50% of thedata (i.e., the interquartilerange) and the horizontalline inside the boxindicates the median valueof a particular element. The tails vertical extendingfrom the boxes indicatethe total range ofabundances determined for eachelement, excluding outliers. Mildoutliers (those between 1.5and 3 times theinterquartile range) are denotedby open circles. Severeoutliers (those greater than3 times the interquartilerange) are denoted byfilled circles.

  7. Ivans et al. (2001) O and Na anticorrelation, Na and Al and CN correlation, seen in previous studies of other globular clusters, expected proton-capture nucleosynthesis (e.g., CN & ON cycle)

  8. Ivans et al. (2001) lower log g: higher O and lower Na, contrary to evolutionary scenario opposite of M13 CN strong vs. weak -- primordial scatter at given CN -- deep mixing

  9. Ivans et al. (2001) <More enhanced in clusters>

  10. Ivans et al. (2001) heavier a- and Fe peak abundance diversity Proton-capture s, r-process

  11. Ivans et al. (2001) HB Index (B-R)/(B+V+R) Lee, Demarque, Zinn (1994) M71 = -1.00 M4 = -0.07 M5 = 0.37 M3 = 0.08 M10 = 0.94 M13 = 0.97 M2 = 0.96 NGC6752 = 1.00 Blue tail vs. Super O-poor??

  12. Cohen, Briley & Stetson (2002) - C & N variations at the base of the RGB Keck LRIS coverage from 3600 to 4800A CN band at 3885A G band of CH at 4300A Main sample is LLG stars: (similar evolutionary state) Signal is too low for a detailed analysis

  13. Cohen, Briley, & Stetson (2002) Arbitrarily divided CH-strong and CH-weak sample

  14. Cohen, Briley, & Stetson (2002) strong anticorrelation among SGBs

  15. Cohen, Briley, & Stetson (2002) Briley et al. (1992): more luminous giants

  16. Cohen, Briley, & Stetson (2002) Requires nearly a 0.75 dex star-to-star variation in [C/Fe] among SGB stars

  17. Cohen, Briley, & Stetson (2002) C & N anticorrelation among SGB stars Nosystematic trends with eitherluminosity or temperature areapparent in the abundances.

  18. Cohen, Briley, & Stetson (2002) Sum ofthe derived C andN abundances is plottedas a function ofthe C abundance. Largefilled circle marks thelocation for both Cand N depleted bya factor of 16, adopting the abundance ofM5 of [Fe/H] =-1.2 dex, with C/Nat the solar ratio. Horizontal line extending tothe left of thatrepresents the locus ofpoints for C graduallybeing converted into N, with the left endof the line havingC/C0 = 0.1. “The rangeof variation of theN abundances is verylarge, and the sumof C+N increases asC decreases. To reproducethis requires the incorporation not only of CNbut also of ON-processedmaterial.”

  19. Ramirez & Cohen (2003) - 25 stars covering a wide range in luminosity Keck (HIRES) wavelength range (6000 ~ 8000A) (c.f., Ivans et al. (5400 ~ 6700A)) Photometry from Stetson et al. (1998)

  20. Ramirez & Cohen (2003) [Fe/H] fromFe I (top) andFe II (bottom) againstphotometric Teff. The solidlines are linear fitsweighted by the errors. The dashed lines indicate the mean [Fe/H] with their respective error plotted as an error bar at 4000 K. In both cases, [Fe/H]shows no dependence onTeff. Note that <[Fe/H](Fe I)> = -1.30 ± 0.02and <[Fe/H](Fe II)> = -1.28 ± 0.02. “at this metallicity, non-LTE effects are not important…” “Thévenin & Idiart (1999) found that non-LTE corrections become more important as [Fe/H] decreases, being about 0.2 dex for stars with [Fe/H] about -1.25 dex, and that ionized lines are not significantly affected by non-LTE.”

  21. Ivans et al. (2001) <[Fe/H]> = -1.21 based on FeII, adopting non-LTE precepts <[Fe/H]> = -1.34 based on FeI e.g., M4, <[Fe/H]> = -1.08, redetermined, -1.17 if based on FeI c.f., M71,<[Fe/H](Fe II)> = -0.84 ± 0.12and <[Fe/H](Fe I)> = -0.71 ± 0.08

  22. Ramirez & Cohen (2003) Abundance ratios of Oand Na with respectto Fe against Teff. The solid line isa linear fit weightedby the errors. Thedashed line indicates themean abundance ratio withits respective error plottedas an error barat 4000 K. Theopen triangle corresponds tothe abundance determined fromthe summed spectra ofthe six m.-s. stars. Arrows represent upper limitsfor the oxygen abundanceratio. Stars G18450_0453 andG18564_0457with similar Te, part of whosespectra are shown inFig. 11 (next slide), are marked withsquares in the [Na/Fe]plot (bottom). ->The scatter shownby [Na/Fe] is dueto real abundance variations among stars of similarTeff.

  23. Ramirez & Cohen (2003) G18450_0453 (5170 K, [Na/Fe] = +0.30) G18564_0457 (5400 K,[Na/Fe] = -0.27).

  24. Ramirez & Cohen (2003) Summaryof abundance ratios inM5. The thick lineon the left sideof the box isthe predicted error (expectedfor the interquartile range), which includes the dependenceon the stellar parametersand the equivalent-width determination.

  25. Ramirez & Cohen (2003) O “The difference of+0.24 dex in themean O abundance presumablyreflects our inability todetect weak O lines in the O-poor low-luminositypart of our samplein M5, assuming theyare actually present there.” Al “althoughthe 6696, 6698 ÅAl I doublet is the most useful featureof that element inthis spectral region, wecould not get itto fit into asingle HIRES setting togetherwith the O lines. Ivans et al. (2001)

  26. Ramirez & Cohen (2003)

  27. Ramirez & Cohen (2003) - [Na/Fe] against [O/Fe] forour sample of M5stars. Arrows represent upperlimits for the [O/Fe]abundance ratio. The opentriangle corresponds to themean abundance of thesix main-sequence stars. [Na/Fe] against [O/Fe] forstars in M5 fromour analysis, showing cleardetections (filled triangles), mean m.-s.stars (open triangle), and othersfrom the literature. The dashed line corresponds to the Na-O anticorrelation present in M4 from the analysis of Ivans et al. (1999), shown as a fiducial line.

  28. Ramirez & Cohen (2003) – very similar abundance ratios btw. M5 & M71 may be due to difficulties in the analysis Comparison of theabundance ratios for allelements common to ouranalysis of similar datafor 25 stars inM71 (Ramírez & Cohen 2002; triangles) andin M5 (squares). Cu in M5: based on single line

  29. Briley, Cohen & Stetson (2004, astro-ph/0312315) -- M13 Briley, Harbeck & Smith (2004, astro-ph/0312316) -- 47 Tuc “pollution/accretion via AGB ejecta” “But rather than simple surface pollution, a substantial fraction of the present stars’ masses must be involved.” C depletion do appear smaller in accord with the prediction of AGB ejecta models of Ventura et al. (2001) …accretion of C-poor materials….to explain the gap & similar spread of [N/Fe], [O/Fe] and [Na/Fe] are needed….

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