CNO and F abundances in the globular cluster M22 (2012, A&A, 540, 3)

Transcription

1 CNO and F abundances in the globular cluster M22 (2012, A&A, 540, 3) Alan Alves-Brito ARC Super Science Fellow Gemini Science Meeting 2012: San Francisco, USA, July

2 Collaborators q David Yong (RSAA, Australia) q Jorge Meléndez (IAG/USP, Brazil) q Sergio Vásquez (PUC, Chile) q Amanda Karakas (RSAA, Australia) Gemini Science Meeting 2012: San Francisco, USA, July

3 The Galactic GC system Bica et al. (2006) M22: metal-poor inner halo Galactic GC MP MR Catalogue used: Harris 1996 [Fe/H] = log(fe/h)_star - log(fe/h)_sun Gemini Science Meeting 2012: San Francisco, USA, July

4 Globular Clusters: Simple Stellar Populations (SSPs)? Characterizing a SSP: (Renzini & Buzzoni 1986) q Age q Composition (Y and Z) q IMF Gemini Science Meeting 2012: San Francisco, USA, July

5 Photometry: GCs ARE NOT SSPs Galactic Extragalactic NGC1851: Milone et al NGC2808: Piotto et al LMC NGC1846: Mackey et al Gemini Science Meeting 2012: San Francisco, USA, July

6 Spectroscopy: GCs ARE NOT SSPs q More than 30 years: Li, C, N, O, Na, Mg, Al (and F) Cohen (1978); Peterson (1980); Cottrell & Da Costa (1981) CN bimodality; CN-CH, Li-Na-O, and Mg-Al (anti)correlations 47 Tuc NGC 6752 Norris & Freeman 1979 Yong et al Carretta et al Gemini Science Meeting 2012: San Francisco, USA, July

7 How to solve this puzzle? q Cottrell & Da Costa (1981): chemical anomalies might be primordial e.g. Cannon et al. 1998; Gratton et al q Anticorrelations comes from HOT hydrogen burning: C(NO), Ne-Na, Mg-Al 1. IM-AGB stars (4 8 Msun) experiencing Hot Bottom Burning (e.g. Cottrell & Da Costa 1981; Ventura & D Antona 2009) 2. (Winds of) Fast Rotating Massive Stars (20-120Msun, e.g. Decressin et al. 2007) Gemini Science Meeting 2012: San Francisco, USA, July

8 Why should we study M22? q CO, CH, A(Ca) and CN variations (Norris & Freeman 1983; Brown et al. 1990; Kayser et al. 2008) q Is there a [Fe/H] abundance spread in this GC? - R limited to 20,000 (Pilachowski et al. 1982; Brown et. Al 1990; Cohen 1981; Gratton 1982; Ivans et al. 2004): controversial results - High R (Marino et al. 2009, 2011) : FLAMES-UVES/VLT: elements Piotto Low R (Da Costa et al. 2009): FORS2/VLT: iron - High R (Roderer et al. 2011): MIKE/Magellan: r/s process Gemini Science Meeting 2012: San Francisco, USA, July

9 Observations and Main Goal 1. Fe, CNO and F 2. F: GCs vs. Field q Gemini South q 11 stars : 6.93 < H < 7.98 q P > 87% 3. CEM and F: astrophysical site q 4 stars with Fe-spread ~ 0.5 dex q H and K bands: R = 55,000 q S/N ~ 100 Gemini Science Meeting 2012: San Francisco, USA, July

10 CNO and Fe: Astrophysical Sites C, N (Gyrs) O (Myrs) and Fe (Gyrs) e.g., Chiappini et al. 2004; Kobayashi et al Gemini Science Meeting 2012: San Francisco, USA, July

11 What about F? Grevesse & Sauval 1998 q Neutrino spallation: SNeII (Woosley & Haxton 1988) q He-rich intershell of TP-AGB stars (Jorissen et al. 1992; Cristallo et al. 2009; Karakas & Lattanzio 2007) q He-burning core of Wolf-Rayet stars (Meynet & Arnould 2000) Gemini Science Meeting 2012: San Francisco, USA, July

12 [Fe/H] -1.9 < [Fe/H] < -1.4 s-poor s-rich N = 42 stars M22 ω Cen (Brown & Wallerstein 1992, see also Marino et al. 2011) s = ([Ba/Fe] + [La/Fe])/2 Da Costa et al. 2009, but see also Marino et al Gemini Science Meeting 2012: San Francisco, USA, July

13 [(C,N,O, Na)/Fe] s-poor s-rich <A(C+N+O)> = / ΔA(C+N+O) ~ 0.7 dex q <A(C+N+O)> = / (s-rich) q <A(C+N+O)> = / (s-poor) Gemini Science Meeting 2012: San Francisco, USA, July

14 Field vs. GCs: A(F) vs. A(O) A(F) ~ 0.6 dex : < [F/O] < 0.27 Field stars: Cunha et al. 2003,2008; Cunha & Smith 2005 GC stars: M4 (, Smith et al. 2005); NGC6712 (X, Yong et al. 2008); and Omega Cen (, Cunha et al. 2003) s-poor s-rich Gemini Science Meeting 2012: San Francisco, USA, July

15 Field vs. GCs: [F/O] vs. [O/H] Kobayashi et al q Neutrino spallation: SNeII (Woosley & Haxton 1988) q He-rich intershell of TP-AGB stars (Jorissen et al. 1992; Cristallo et al. 2009; Karakas & Lattanzio 2007) Gemini Science Meeting 2012: San Francisco, USA, July

16 Conclusions and Perspectives Our study confirms and expands upon the chemical diversity seen in this complex stellar system, where both q There is a Δ[Fe/H] in M22 of ~0.4 dex q Large dispersion massive and in the low mass light C, stars N, have and contributed O elements q A(C+N+O) ~ 0.7 dex; cte in the M22 s-process groups q Na-O anticorrelated Further investigation is necessary: GCs vs. field q F abundance spread of 0.6 dex is found q [F/O] vs. [O/H]: both SNeII and AGBs Gemini Science Meeting 2012: San Francisco, USA, July

17 Thank you very much Gemini Science Meeting 2012: San Francisco, USA, July

18 Uncertainties T = ±100K : logg = ±0.30 dex : v = ±0.20 Km/s C: 0.10 dex F: 0.17 dex N: 0.13 dex Na: 0.08 dex O: 0.10 dex Fe: 0.04 dex Gemini Science Meeting 2012: San Francisco, USA, July

19 E(B-V) in our M22 sample Gemini Science Meeting 2012: San Francisco, USA, July

20 Field vs. GCs: A(F) vs. A(C) s-poor s-rich Gemini Science Meeting 2012: San Francisco, USA, July

21 [F/O] vs. s-process M4 s-poor s-rich Omega Cen Gemini Science Meeting 2012: San Francisco, USA, July