2011A&A...535A..31V


Query : 2011A&A...535A..31V

2011A&A...535A..31V - Astronomy and Astrophysics, volume 535A, 31-31 (2011/11-1)

Bimodality of light and s-elements in M4 (NGC 6121). A hint for the massive main-sequence star pollution scenario.

VILLANOVA S. and GEISLER D.

Abstract (from CDS):

All globular clusters (GCs) studied in detail host two or more populations of stars (the multiple population phenomenon). Theoretical models suggest that the second population is formed from gas polluted by processed material produced by massive stars of the first generation. However the nature of the polluters is matter of strong debate. Several candidates have been proposed: massive main-sequence stars (fast rotating or binaries), intermediate-mass AGB stars, or SNeII. We studied red giant branch (RGB) stars in the GC M4 (NGC 6121) to measure their chemical signature. Our goal is to measure abundances for many key elements (from Li to Eu) in order to derive constraints on the polluters responsible for the multiple populations. We observed 23 RGB stars below the RGB-bump using the GIRAFFE spectroscopic facility installed on VLT2. Spectra cover a wide range and allowed us to measure light (Li, C, 12C/13C, N, O, Na, Mg, Al), α (Si, Ca, Ti), iron-peak (Cr, Fe, Ni), light-s (Y), heavy-s (Ba), and r (Eu) elements. We supplemented this study by analyzing an additional subsample of the UVES spectra in order to gather further clues about light s-elements of different atomic number (Y and Zr). We confirm the presence of a bimodal population. Stars can be easily separated according to their N content. The two groups have different C, 12C/13C, N, O, Na content, but share the same Li, C+N+O, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zr, Ba and Eu abundance. Quite surprisingly the two groups differ also in their Y abundance. This result is strongly supported also by the analysis of the UVES spectra. The absence of a spread in α-elements, Eu and Ba makes SNeII and AGB stars unlikely as polluters. On the other hand, massive main-sequence stars can explain the bimodality of Y through the weak s-process. This statement is confirmed independently also by literature data on Rb and Pb. The lack of a Mg/Al spread and the extension of the [O/Na] distribution suggest that the mass of the polluters is between 20 and 30M. This implies a formation time scale for the cluster of 10/30Myr. This result is valid for M4. Other clusters such as NGC 1851, M 22, or ω Cen have different chemical signatures and may require other kinds of polluters.

Abstract Copyright:

Journal keyword(s): stars: abundances - globular clusters: individual: M4

Nomenclature: Table 1: Cl* NGC 6121 MVP NNNNN N=23 among (Nos 907-67553) added.

Simbad objects: 53

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Number of rows : 53
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 1851 GlC 05 14 06.76 -40 02 47.6           ~ 1289 0
2 NGC 2808 GlC 09 12 03.10 -64 51 48.6           ~ 1296 0
3 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3120 0
4 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2186 0
5 Cl* NGC 6121 MVP 33584 * 16 23 09.9290127891 -26 28 33.625132832 16.14 15.60 14.50     ~ 2 0
6 2MASS J16231395-2633244 RG* 16 23 13.9483756854 -26 33 24.538221029 14.89 13.556 12.055   10.286 ~ 27 0
7 2MASS J16231442-2636055 RG* 16 23 14.424 -26 36 05.53 14.64 12.73 10.88 9.80 9.04 ~ 43 0
8 2MASS J16231459-2630469 RG* 16 23 14.5988454138 -26 30 46.990554395 15.05 13.901 12.482   10.813 ~ 16 0
9 Cl* NGC 6121 MVP 28590 * 16 23 15.4533826350 -26 38 47.246293987 16.13 15.60 14.52     ~ 2 0
10 2MASS J16231655-2632095 RG* 16 23 16.5622382734 -26 32 09.735015041 14.79 13.236 11.661   9.896 ~ 32 0
11 2MASS J16231690-2629479 RG* 16 23 16.9015287519 -26 29 47.955132376 15.28 14.389 13.100   11.559 ~ 16 0
12 Cl* NGC 6121 ALC 270 * 16 23 21.4120549214 -26 28 33.575913935 16.17 15.54 14.42     ~ 5 0
13 2MASS J16232305-2633322 RG* 16 23 23.0552208994 -26 33 32.339288945 15.28 14.413 13.112   11.546 ~ 12 0
14 2MASS J16232354-2633412 RG* 16 23 23.5444331535 -26 33 41.334508333 15.18 14.40 13.109   11.463 ~ 11 0
15 Cl* NGC 6121 ALC 402 * 16 23 23.7416809785 -26 33 21.938838069 16.23 15.669 14.524     ~ 4 0
16 CD-26 11312 RG* 16 23 23.8093142318 -26 34 29.822263715 14.75 12.63 10.76   8.51 ~ 36 0
17 2MASS J16232530-2633291 RG* 16 23 25.3050480062 -26 33 29.260431872 15.17 14.157 12.815   11.201 ~ 13 0
18 2MASS J16232708-2633297 RG* 16 23 27.0854369425 -26 33 29.755728714 15.32 14.630 13.361   11.786 ~ 13 0
19 Cl* NGC 6121 MVP 47596 * 16 23 27.09000 -26 31 23.7000 16.07 15.58 14.46     ~ 1 0
20 Cl* NGC 6121 ALC 394 * 16 23 27.7200360577 -26 33 41.862668904 16.33 15.736 14.547     ~ 4 0
21 Cl* NGC 6121 ALC 406 * 16 23 27.7488651314 -26 32 32.029862973 16.26 15.711 14.526     ~ 4 0
22 Cl* NGC 6121 ALC 391 * 16 23 28.2763855197 -26 34 27.946911278 16.40 15.839 14.668     ~ 4 0
23 Cl* NGC 6121 LEE 1618 * 16 23 30.8339111943 -26 33 28.092199200 16.28 15.778 14.611     ~ 4 0
24 Cl* NGC 6121 MVP 43020 * 16 23 30.940 -26 33 44.30 16.48 15.99 14.87     ~ 2 0
25 2MASS J16233337-2633148 RG* 16 23 33.3814162539 -26 33 14.943031899 15.65 14.864 13.612   12.079 ~ 13 0
26 Cl* NGC 6121 ALC 535 * 16 23 33.5069221917 -26 30 35.055975918 16.26 15.793 14.642     ~ 4 0
27 2MASS J16233412-2633039 RG* 16 23 34.1256926660 -26 33 03.927810876 15.48 14.75 13.470   11.847 ~ 12 0
28 2MASS J16233418-2632485 RG* 16 23 34.1844049488 -26 32 48.546379290 15.52 14.832 13.595   12.063 ~ 8 0
29 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1724 0
30 2MASS J16233712-2633500 RG* 16 23 37.1346817293 -26 33 50.098391691 15.43 14.76 13.489   11.856 ~ 9 0
31 2MASS J16233825-2635551 RG* 16 23 38.2590685910 -26 35 55.198865868 15.69 14.94 13.668   12.055 ~ 12 0
32 2MASS J16234000-2639029 RG* 16 23 40.0066841945 -26 39 03.171504497 16.89 14.668 13.443   11.916 ~ 11 0
33 2MASS J16234091-2637234 RG* 16 23 40.9203802137 -26 37 23.518223109 15.11 14.234 12.934   11.362 ~ 17 0
34 Cl* NGC 6121 MVP 45200 * 16 23 41.420 -26 32 31.00 16.36 15.78 14.65     ~ 2 0
35 2MASS J16234260-2633174 RG* 16 23 42.6021909443 -26 33 17.494586082 15.53 14.961 13.793   12.23 ~ 7 0
36 Cl* NGC 6121 MVP 46201 * 16 23 44.00000 -26 32 01.8000 15.98 15.47 14.38     ~ 1 0
37 Cl* NGC 6121 ALC 198 * 16 23 44.4191352929 -26 35 37.238319417 16.33 15.772 14.660     ~ 4 0
38 Cl* NGC 6121 ALC 152 * 16 23 44.59 -26 38 03.3 16.13 15.692 14.538     ~ 4 0
39 Cl* NGC 6121 MVP 50032 * 16 23 45.3730878256 -26 30 16.378048904 16.13 15.59 14.50     ~ 6 0
40 Cl* NGC 6121 SAW V56 RG* 16 23 45.9298474046 -26 33 38.945212420 15.02 14.24 12.93 12.13 11.35 ~ 20 0
41 Cl* NGC 6121 SAW V57 RG* 16 23 46.9275656202 -26 33 43.897229794 15.22 14.256 12.980   11.341 ~ 19 0
42 Cl* NGC 6121 MVP 8460 * 16 23 47.3275650153 -26 22 30.070415529 16.14 15.47 14.37     ~ 4 0
43 Cl* NGC 6121 MVP 39100 * 16 23 48.7039952909 -26 36 25.857644742 16.04 15.54 14.40     ~ 4 0
44 2MASS J16234879-2635093 RG* 16 23 48.7980557407 -26 35 09.188087278   13.219 11.691   9.909 ~ 11 0
45 Cl* NGC 6121 ALC 484 * 16 23 48.9671100775 -26 30 59.083282280 15.92 15.398 14.271     ~ 5 0
46 Cl* NGC 6121 LEE 4510 * 16 23 49.0759093639 -26 34 00.541185855 16.22 15.652 14.548     ~ 4 0
47 2MASS J16235358-2634151 RG* 16 23 53.5834333280 -26 34 15.161212344 14.93 13.892 12.534   10.908 ~ 24 0
48 2MASS J16235384-2633525 RG* 16 23 53.8474818308 -26 33 52.538417274 15.13 14.193 12.892   11.327 ~ 18 0
49 Cl* NGC 6121 MVP 36820 * 16 23 55.71000 -26 39 00.7000 16.33 15.81 14.69     ~ 1 0
50 Cl* NGC 6121 ALC 96 * 16 24 00.6065440362 -26 28 20.751673065 15.77 15.266 14.173     ~ 4 0
51 Cl* NGC 6121 MVP 907 * 16 24 08.98000 -26 22 40.5000 15.81 15.31 14.21     ~ 1 0
52 NGC 6397 GlC 17 40 42.09 -53 40 27.6   7.39 5.17     ~ 1844 1
53 M 22 GlC 18 36 23.94 -23 54 17.1   7.16 6.17     ~ 1262 0

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2021.08.02-23:30:46

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