PoS(NIC XI)201 ω http://pos.sissa.it/ ∗ [email protected] [email protected] [email protected] Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. c

J. D. Simpson University of Canterbury, Private Bag 4800,E-mail: Christchurch 8140, New Zealand P. L. Cottrell University of Canterbury, Private Bag 4800,E-mail: Christchurch 8140, New Zealand C. C. Worley Université de Nice Sophia Antipolis, CNRSCassiopée, (UMR B.P.4229, 06304 6202), Nice Observatoire Cedex de 04, laUniversity France Côte of d’Azur, Canterbury, Private Bag 4800,E-mail: Christchurch 8140, New Zealand Neutron-capture element abundances in the globular clusters: 47 Tuc, NGC 6388,Cen NGC 362 & PoS(NIC XI)201 =  32 . /Fe] ] with 0 09 dex, ls . hs / = 0 hs  /Fe] 56 ls . 0 02 dex, [ . = 0  /Fe] ls 53 . -process ([ s 0 = -process elements indicates a s /Fe] ls 16 dex). A comparison between the . 0 -process element abundance distribution  s 17 . 0 -process elements of [ s 14 dex and [ . 0 Cen, using high- and medium- resolution data. = + ]  ω ls / 17 . hs 000) data from van Loon et al. (2007) has been used to 0 , 08 dex, respectively. In NGC 362 the showed heavy − 2 . 0 = ∼ : Ba, La, Nd) ]  ls hs / 13 . 13 dex , [ hs . 0 0 −  = ] 49 . ls / 0 10 dex , [ hs . = , [Fe/H] and [Ba/Fe] for up to 500 stars. [Ba/Fe] enhancements up to +1.0 dex 0 -process element abundances throughout the HR diagram. g s  /Fe] -process elements internally. Hence the 39 , log hs s . 0 07 dex, [ . e f f : Y, Sr, Zr) and heavy ( Cen medium resolution (R 0 = ls  ω /Fe] 40 10 dex, [ . . -process element abundances that were more enhanced than the light -process element abundances of each clusters show a general trend of increasing [ hs The authors wish to thank the New Zealand Marsden Fund, the University of Canterbury, the Observatoire de la derive T 0 0 were determined, uncorrelated with the CN,of CH the indices. use of We the also FPI presentrameters technique our for to initial a determine exploration large n-capture sample element ofassessments abundances of stars and in other a stellar range pa- of globular clusters. This will enable us to make A spectroscopic study of neutron-capture element abundancesclusters, has 47 been Tuc, carried NGC out 6388, in NGC theThe 362 globular stars and analysed at high(UVES) resolution, on using the data Very acquired Large with Telescopetotic Ultraviolet (VLT), giant were Echelle luminous branch Spectrograph giant for starsanalysed 47 located stars Tuc, that near reached NGC the below 6388 asymp- theWe level and are of also NGC the exploring horizontal 362. the branch possibility interferometer The of at (FPI) undertaking least medium on large-scale one resolution the studies cluster, Robert 47 using studies Tuc. Stobie theWith have Spectrograph Fabry–Pérot the In- on high the resolution Southern UVES Africanand data, Large two Telescope. eleven stars stars were in analysedlight NGC in ( NGC 362. 6388, five The stars[ in NGC 47 6388 Tuc and 47 Tuc stars showed enhancementss in the s represents a pre-existing chemical signaturemedium for resolution each study cluster. had been The less previousThe conclusive. (Worley et al. 2008) decreasing [Fe/H]. The smallhomogeneous spread in distribution the within abundances eachproducing of cluster, these confirming that the stars analysed here are not ∗ Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. c

Côte d’Azur and the LOC/SOCattend of this NIC meeting. XI for their financial support which enabled C. C. Worley and P. L. Cottrell to 11th Symposium on Nuclei in theJuly Cosmos, 19-23, NIC 2010 XI Heidelberg, Germany PoS(NIC XI)201 hs

0.9 = Ba, hs 0.8 0.7 NGC 362 -process element s 0.6 [Eu/Fe] -process (i.e. NGC 6388 0.5 elements. Determining s ls 0.4 47 Tuc indicates homogeneity of these [hs/Eu] [ls/Eu] ls 0.3 and

0.2 0

0.4 0.3 0.2 0.1

−0.3 −0.4 −0.5 −0.1 −0.2 hs [X/Eu] for both 47 Tuc and NGC 6388, which are element abundances are due to pollution by b) hs hs = Y, Sr, Zr) and heavy 2 ls element signatures as a ratio to the Eu abundance and ls hs -process elements can also have contributions from the

s −0.5 and ls −0.6 /Eu] against [Eu/Fe]. Values above zero indicate NGC 6388 ls -process (i.e. −0.7 s [hs/Fe] [ls/Fe] [Eu/Fe] −0.8 is more enhanced than /Fe] and [Eu/Fe] vs [Fe/H] for NGC 362 (blue), 47 Tuc (magenta) and NGC ls ls /Eu] (and [ −0.9 47 Tuc [Fe/H] hs −1 /Fe],[ hs elements show enhancement in all three clusters, as seen in Figure 1. Considered −1.1 -process elements (i.e. Eu); thermally pulsing asymptotic giant branch stars (TP- r -process element, Eu, can be used as an indicator of the degree of contribution of ls r . However, −1.2 ls NGC 362 and /Eu]). The comparably small spreads in Fe, Eu, a) Mean [ −1.3 hs hs

0.5 0.4 0.3 0.2 0.8 0.7 0.6 [X/Fe] Figure 1b compares the residual The The high resolution spectra of the luminous giants in the GCs 47 Tuc, NGC 6388 and NGC 362 There are three key sites of nuetron-capture (n-capture) element nucleosynthesis: Supernova /Eu],[ a) ls -process. The ([ alone it could be assumedTP-AGB that stars. source However, of the so the designated r more metal rich and less enhanced in Eu. n-capture elements due to pollution byenhanced in Type II all Supernova. three clusters, Also particularly shown for in NGC Figure 362, 1a, which Eu has is the clearly greatest enhancement in residual enhancements. compared to elements in all three clusters, which is evidence that the observed stars are not producing these Figure 1: 6388 (red) as indicated by theb) symbols As for in a) the but legend. showing The [ errorbars are the standard deviation for each GC. La, Nd) elements; andthe massive abundance He-core distribution burning of stars theseastronomers which to n-capture produce dis-entangle elements the within pollution events globular that cluster occured (GC) during the stars evolution allows of the GC. AGB) which produce both light were observed using UVES on the VLT forvan a Loon, programme investigating 2007). mass loss rates A (McDonald& dances subsample (Worley of et the al. stars 2010, werestars Worley then & is analysed Cottrell, continuing for 2010). and their this Theto n-capture paper chemical include element refines abundance corrections abun- the analysis for values of hyperfine obtained these element splitting. abundances for We derived the present for these Ba these values and stars. with Eu the abundances previous so n-capture as 2. n-capture element abundances: 47 Tuc, NGC 6388 & NGC 362 Type II produce n-capture element abundances in globular clusters 1. Introduction PoS(NIC XI)201 hs 4500, and = ls e f f ) and the [Ba/Fe] 1 − only, indicating later pollution Cen using the 2dF instrument of ls ω 3 -process contribution to the n-capture elements and r -process signature. s 2000. It includes the Ba II spectral line centered at 4555 Å. , [Fe/H], with microturbulence of 2 kms g ∼ -process signature showed enhancements in both the s , log 5. Synthetic spectra generated using this model with variations in e f f . 1 -process signature indicating no secondary n-capture element pollution. s − = -process signature showed enhancements in s Cen > 0. This indicates later pollution by low or intermediate mass TP-AGB. In NGC 6388 ω 0 and [Fe/H] . hs 1 > = ls An analysis is currently being undertaken using the data set of van Loon et al. (2007) (vL07). The stellar parameters (T Parameters from vL07 are being using in conjunction with parameters from Johnson et al. The Fabry-Perot interferometer (FPI) can be used as a tunable narrow-bandwidth filter to sam- These n-capture element abundance signatures suggest the following pollution scenarios for g -process element abundances in the stars that feature Ba enhancements. This is a spectral atlas of the post-main-sequence population in by low mass TP-AGB or massive He-core burningSupernova . but For no NGC residual 362 there was pollution by Type II the AAO, with spectral resolution of ratio were determined herecompare using favourably the with wavelength those intervalabundances found 4510 rather than by Å the Ba vL07 to index of and 4590 vL07.correlation Å. J09, between Using high CN These and (low) and barium CH parameters provide abundances indices in defined athe the by stars. stars large vL07 and Figure there high dataset 2a is (low) shows no of carbon the abundances spectrafive [Ba/Fe] in of stars five were vL07 found stars to that be have best a fittedlog range by of a barium stellar abundances. model All atmosphere with parameters of T 3. Ba in (2009) (J09) who used thesured Blanco 66 4 stars m from a telescope wider andthe data Hydra van set Loon multi-fiber of spectra spectrograph. which are there being They were compared mea- 38 to in synthetic common spectra with produced vL07. by In MOOG this (Sneden analysis 1973). there was also some initial pollution47 Tuc. by The Type residual II Supernova, although less Eu enhancement than in This line is being used to determine the [Ba/Fe] of the 1,500 stars in the vL07 data set. Ba abundances are included indiagram (CMD) Figure is 2a. shown in The Figuredata placement 2b. set This of work and these will to stars be extendeds in look to the at the colour-magnitude analysis other of spectral the features full vL07 to determine if thereple are a overall spectral enhancements line of imaging in the each field star at inthousands a the of series field stellar of of spectra wavelengths view canspectroscopy that simultaneously be techniques. cover (Rangwala obtained a et without Using spectral al. the theSouthern feature, African overhead FPI hundreds 2009). Large involved mode Telescope and in (SALT) on it By perhaps other willwith the multi-object be a Robert possible spectral to resolution Stobie observe of Spectrograph the about 6496.9 (RSS) 8,000. Å of line of the Ba II n-capture element abundances in globular clusters elements internally but rather they areclusters’ history. the In chemical doing signature this of wewhat pollution remove events remains the in is the the respective signaturecluster of shows a pollution distinctly by different residual some other event (TP-AGBs, massive stars). Each with each of the clusters. For 47the Tuc, Eu initially abundances. there was The pollution by residual Type II Supernova as indicated by PoS(NIC XI)201 , The University of , 209 698 A Large Sample Study of Red Giants , Heavy-element abundances in , 2060 , 1261 ApJ 402 476 , , , 2009, b) A&A Fabry-Perot Absorption Line Spectroscopy of the MNRAS 4 , 2504 , 2007, , 1353 , 138 , 2010, 406 , 382 , 691 , Dust, pulsation, chromospheres and their role in driving mass loss ApJ Heavy element abundances in low gravity stars: MNRAS MNRAS , 2009, , 2010, , 2007, PhD Thesis: Carbon and Nitrogen Abundances in Metal-Poor Stars. A spectral atlas of post-main-sequence stars in ÏL’Centauri: kinematics, evolution, enrichment a) Examples of five spectra taken from the vL07 dataset. The blue line is the observed spectrum. from red giants in Galactic globular clusters low-gravity globular cluster stars: 47 Tuc Galactic Bar. I. Kinematics and interstellar medium NGC 362 and NGC 6388 in the Globular Cluster (NGC 5139) Texas at Austin, 1973 M. L., These two lines of analysis have so far focussed on n-capture element abundances. However, a) the abundances of key elementspotential lighter pollution than scenarios iron that will occurredboth provide in medium- further and each discrimination high- of between resolution these the will four be made clusters. to Further further complete observations thisReferences in picture. [1] McDonald, I., and van Loon, J. T., 4. Conclusion [2] Worley, C. C., Cottrell, P. L., McDonald, I., and van Loon, J. T., Figure 2: The red lines areb) synthetic The spectra CMD with of barium theincreasing enhancements B vL07 corresponding magnitude data to they set. are +0.0, 77025, +0.5 Highlighted 49013, 85027, and are 9 +1.0 the and stars dex. 30013. which are featured in Figure 2a. In order of [7] Rangwala, N., Williams, T. B., and Stanek, K. Z., n-capture element abundances in globular clusters [3] Worley, C. C., and Cottrell, P. L., [4] Johnson, C. I., Pilachowski, C. A., Rich, R. M., and[5] Fulbright, J., Sneden, C., [6] Van Loon, J. T., van Leeuwen, F., Smalley, B., Smith, A. W., Lyons, N., McDonald, I., and Boyer,