2011A&A...527A.148L

Query : 2011A&A...527A.148L

2011A&A...527A.148L - Astronomy and Astrophysics, volume 527A148-148 (2011/3-1)

Tracing the evolution of NGC 6397 through the chemical composition of its stellar populations.

LIND K., CHARBONNEL C., DECRESSIN T., PRIMAS F., GRUNDAHL F. and ASPLUND M.

Abstract (from CDS):

The chemical compositions of globular clusters provide important information on the star formation that occurred at very early times in the Galaxy. In particular the abundance patterns of elements with atomic number z≤13 may shed light on the properties of stars that early on enriched parts of the star-forming gas with the rest-products of hydrogen-burning at high temperatures. We analyse and discuss the chemical compositions of a large number of elements in 21 red giant branch stars in the metal-poor globular cluster NGC6397. We compare the derived abundance patterns with theoretical predictions in the framework of the ``wind of fast rotating massive star''-scenario. High-resolution spectra were obtained with the FLAMES/UVES spectrograph on the VLT. We determined non-LTE abundances of Na, and LTE abundances for the remaining 21 elements, including O (from the [OI] line at 630nm), Mg, Al, α, iron-peak, and neutron-capture elements, many of which had not been previously analysed for this cluster. We also considered the influence of possible He enrichment in the analysis of stellar spectra. We find that the Na abundances of evolved, as well as unevolved, stars in NGC6397 show a distinct bimodality, which is indicative of two stellar populations: one primordial stellar generation of composition similar to field stars, and a second generation that is polluted with material processed during hydrogen-burning, i.e., enriched in Na and Al and depleted in O and Mg. The red giant branch exhibits a similar bimodal distribution in the Stroemgren colour index cy=c1-(b-y), implying that there are also large differences in the N abundance. The two populations have the same composition for all analysed elements heavier than Al, within the measurement uncertainty of the analysis, with the possible exception of [Y/Fe]. Using two stars with almost identical stellar parameters, one from each generation, we estimate the difference in He content, ΔY=0.01±0.06, given the assumption that the mass fraction of iron is the same for the stars. NGC6397 hosts two stellar populations that have different chemical compositions of N, O, Na, Mg, and probably Al. The cluster is dominated (75%) by the second generation. We show that massive stars of the first generation can be held responsible for the abundance patterns observed in the second generation long-lived stars of NGC6397. We estimate that the initial mass of this globular cluster is at least ten times higher than its present-day value.

Abstract Copyright: ∼

Journal keyword(s): stars: Population II - globular clusters: individual: NGC 6397 - methods: observational - techniques: spectroscopic - stars: abundances

VizieR on-line data: <Available at CDS (J/A+A/527/A148): table1.dat table2.dat>

Simbad objects: 140

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Number of rows : 140
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20     4.09     ~ 4158 0
2 NGC 2808 GlC 09 12 03.10 -64 51 48.6           ~ 1540 0
3 NGC 5139 GlC 13 26 47.28 -47 28 46.1           ~ 3677 0
4 M 5 GlC 15 18 33.22 +02 04 51.7     5.95     ~ 2095 0
5 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1978 0
6 [LPC2009] 2315 RG* 17 39 33.44 -53 39 15.0     16.892     ~ 2 0
7 2MASS J17393475-5341157 RG* 17 39 34.7704032816 -53 41 15.862439688   15.295 14.519     ~ 6 0
8 2MASS J17393795-5340531 RG* 17 39 37.9629703800 -53 40 53.233347648     15.935   15.01 ~ 3 0
9 2MASS J17393798-5341554 RG* 17 39 37.989 -53 41 55.43     16.241     ~ 2 0
10 2MASS J17393880-5341387 RG* 17 39 38.8093776360 -53 41 38.870417076     16.587     ~ 2 0
11 2MASS J17394052-5343440 RG* 17 39 40.5281359848 -53 43 44.131696140     16.192     ~ 2 0
12 2MASS J17394064-5338179 RG* 17 39 40.644 -53 38 17.98     16.448     ~ 2 0
13 2MASS J17394297-5339253 RG* 17 39 42.9863760576 -53 39 25.445301660     16.231   15.39 ~ 3 0
14 2MASS J17394372-5340506 RG* 17 39 43.7301630552 -53 40 50.711224728   16.44 15.966   15.05 ~ 4 0
15 2MASS J17394424-5340150 RG* 17 39 44.2494888312 -53 40 15.075392160     15.930     ~ 2 0
16 2MASS J17394474-5339465 RG* 17 39 44.7646902408 -53 39 46.606485780     16.263   15.41 ~ 3 0
17 2MASS J17394538-5340560 RG* 17 39 45.3894857448 -53 40 56.143878564     15.914     ~ 2 0
18 [LPC2009] 4355 RG* 17 39 46.04 -53 37 11.2     16.653     ~ 2 0
19 2MASS J17394781-5341066 RG* 17 39 47.8181114160 -53 41 06.756103788   14.388 13.584     ~ 7 0
20 2MASS J17394842-5339252 RG* 17 39 48.425 -53 39 25.20     16.340     ~ 2 0
21 2MASS J17394868-5341370 RG* 17 39 48.6803386440 -53 41 37.081343112     15.813     ~ 2 0
22 2MASS J17394908-5338514 RG* 17 39 49.0948013304 -53 38 51.599208228     16.383     ~ 2 0
23 [LPC2009] 5044 RG* 17 39 49.6581854136 -53 40 41.310770628     16.418     ~ 2 0
24 2MASS J17395095-5342479 RG* 17 39 50.956 -53 42 47.90   16.54 16.060     ~ 3 0
25 [LPC2009] 5361 RG* 17 39 51.13 -53 39 42.9     16.121     ~ 2 0
26 2MASS J17395177-5337192 RG* 17 39 51.7838085528 -53 37 19.402261896     16.436     ~ 2 0
27 [LPC2009] 5577 RG* 17 39 52.0891879272 -53 36 54.090438840     16.318     ~ 2 0
28 TYC 8729-1868-1 RG* 17 39 52.5084252408 -53 39 11.289028644 10.61 12.37 11.53     ~ 11 0
29 2MASS J17395263-5342098 RG* 17 39 52.6433859216 -53 42 10.002301272     16.416     ~ 2 0
30 2MASS J17395321-5337479 RG* 17 39 53.212 -53 37 47.99     16.362     ~ 2 0
31 2MASS J17395364-5338379 RG* 17 39 53.6573821464 -53 38 38.086946772     15.014     ~ 2 0
32 [LPC2009] 6001 RG* 17 39 54.2546361120 -53 39 13.913513820     16.824     ~ 2 0
33 2MASS J17395491-5342240 RG* 17 39 54.9206759256 -53 42 24.298961220     16.171   15.31 ~ 4 0
34 2MASS J17395523-5337289 RG* 17 39 55.2363751176 -53 37 28.987313052     16.528     ~ 2 0
35 [LPC2009] 6301 RG* 17 39 55.7402471736 -53 41 34.189157184     16.117     ~ 2 0
36 2MASS J17395678-5340298 RG* 17 39 56.7916070952 -53 40 29.965931076     15.954   15.08 ~ 4 0
37 2MASS J17395735-5338013 RG* 17 39 57.358 -53 38 01.37     16.335     ~ 2 0
38 2MASS J17395763-5341372 RG* 17 39 57.6484429080 -53 41 37.360731696     16.841     ~ 2 0
39 2MASS J17395770-5338394 RG* 17 39 57.7147411536 -53 38 39.621849252     15.832   14.89 ~ 4 0
40 2MASS J17395835-5337503 RG* 17 39 58.3655736456 -53 37 50.561250096     15.089     ~ 2 0
41 2MASS J17395841-5340453 RG* 17 39 58.4288684736 -53 40 45.531612732     16.339     ~ 3 0
42 2MASS J17395891-5343160 RG* 17 39 58.9163061408 -53 43 16.161291084     15.976   15.09 ~ 4 0
43 2MASS J17395994-5341205 RG* 17 39 59.9419143096 -53 41 20.572505808     15.201     ~ 2 0
44 2MASS J17400019-5340146 RG* 17 40 00.2021419920 -53 40 14.711993868     16.401     ~ 3 0
45 2MASS J17400127-5338451 RG* 17 40 01.2761362104 -53 38 45.220997328     16.417     ~ 2 0
46 2MASS J17400152-5343467 RG* 17 40 01.5245688048 -53 43 46.863165288     15.932   14.98 ~ 4 0
47 2MASS J17400167-5342545 RG* 17 40 01.6670821920 -53 42 54.602887608     14.379     ~ 6 0
48 2MASS J17400168-5337219 RG* 17 40 01.6924589688 -53 37 21.940125276   15.121 14.341     ~ 7 0
49 2MASS J17400190-5340360 RG* 17 40 01.9112351136 -53 40 36.152304852     16.228     ~ 2 0
50 2MASS J17400328-5337226 RG* 17 40 03.2877908808 -53 37 22.779215652     15.334     ~ 3 0
51 2MASS J17400332-5342468 RG* 17 40 03.3243491736 -53 42 46.891680660     16.229   15.38 ~ 4 0
52 2MASS J17400367-5338162 RG* 17 40 03.6803675952 -53 38 16.282159476     16.182     ~ 2 0
53 [LPC2009] 8225 RG* 17 40 03.69 -53 37 58.4     16.703     ~ 2 0
54 2MASS J17400430-5339303 RG* 17 40 04.303 -53 39 30.33     15.971   15.09 ~ 4 0
55 [LPC2009] 8341 RG* 17 40 04.3405764072 -53 40 40.727893584     16.886     ~ 2 0
56 2MASS J17400543-5338198 RG* 17 40 05.4383957304 -53 38 19.899666420     16.119   15.26 ~ 4 0
57 [LPC2009] 8828 RG* 17 40 05.9312451528 -53 37 03.729991044     16.638     ~ 2 0
58 2MASS J17400610-5342244 RG* 17 40 06.1031317896 -53 42 24.514411716   16.47 15.951     ~ 4 0
59 2MASS J17400635-5342090 RG* 17 40 06.354 -53 42 09.05   16.48 15.973   15.07 ~ 5 0
60 2MASS J17400658-5340283 RG* 17 40 06.5934479472 -53 40 28.420427280 11.31 13.297 12.422     ~ 9 0
61 2MASS J17400678-5336361 RG* 17 40 06.7953218136 -53 36 36.221595264     16.559     ~ 2 0
62 2MASS J17400698-5335506 RG* 17 40 07.0008144288 -53 35 50.671199796     16.302     ~ 2 0
63 [LPC2009] 9247 RG* 17 40 07.4574117912 -53 38 44.392261128     16.311     ~ 2 0
64 2MASS J17400804-5337290 RG* 17 40 08.0506810416 -53 37 29.086148496   13.839 12.987     ~ 7 0
65 [LPC2009] 9344 RG* 17 40 08.0535694416 -53 43 55.665153768     15.288     ~ 2 0
66 2MASS J17400841-5342515 RG* 17 40 08.4076426512 -53 42 51.711498612     15.934   15.02 ~ 4 0
67 2MASS J17400873-5340041 RG* 17 40 08.7489270408 -53 40 04.247632848     16.304     ~ 2 0
68 2MASS J17400904-5342360 RG* 17 40 09.0453785016 -53 42 36.144129492   14.225 13.410     ~ 7 0
69 2MASS J17401022-5337461 RG* 17 40 10.2405078264 -53 37 46.170863904     16.609     ~ 2 0
70 2MASS J17401045-5338325 RG* 17 40 10.4663005680 -53 38 32.612002260     16.644     ~ 2 0
71 2MASS J17401130-5340060 RG* 17 40 11.309 -53 40 06.01     16.529     ~ 2 0
72 2MASS J17401133-5341559 RG* 17 40 11.335 -53 41 55.99     16.209     ~ 2 0
73 2MASS J17401203-5337160 RG* 17 40 12.0427975416 -53 37 16.028883444     16.258     ~ 2 0
74 2MASS J17401225-5336451 RG* 17 40 12.2550901656 -53 36 45.258201684     16.413     ~ 2 0
75 2MASS J17401283-5343118 RG* 17 40 12.8326520928 -53 43 11.931069108 11.39 13.435 12.540     ~ 9 0
76 [LPC2009] 10849 RG* 17 40 12.96 -53 38 29.5     16.561     ~ 2 0
77 2MASS J17401365-5340015 RG* 17 40 13.6607200344 -53 40 01.679160576     16.741     ~ 3 0
78 2MASS J17401372-5339153 RG* 17 40 13.7204045136 -53 39 15.489134244     16.238   15.43 ~ 4 0
79 2MASS J17401406-5340406 RG* 17 40 14.0789158368 -53 40 40.773538776     16.368     ~ 2 0
80 2MASS J17401411-5343192 RG* 17 40 14.1164983584 -53 43 19.300184328   15.090 14.308     ~ 7 0
81 [LPC2009] 11253 RG* 17 40 14.31 -53 38 55.5     16.014     ~ 2 0
82 2MASS J17401476-5341440 RG* 17 40 14.7796539048 -53 41 44.114348544   14.160 13.350     ~ 7 0
83 2MASS J17401482-5337284 RG* 17 40 14.827 -53 37 28.42     16.281     ~ 2 0
84 2MASS J17401487-5338377 RG* 17 40 14.87808 -53 38 37.7304   16.42 15.901     ~ 4 0
85 2MASS J17401533-5343058 RG* 17 40 15.3257183784 -53 43 05.843447508     16.174     ~ 2 0
86 [LPC2009] 11621 RG* 17 40 15.67 -53 42 19.4     16.545     ~ 2 0
87 2MASS J17401704-5335531 RG* 17 40 17.0563614552 -53 35 53.162717244     16.348     ~ 2 0
88 2MASS J17401715-5338213 RG* 17 40 17.1547129128 -53 38 21.431540616     16.570     ~ 2 0
89 2MASS J17401717-5336141 RG* 17 40 17.1847703496 -53 36 14.221093176     16.411     ~ 2 0
90 TYC 8729-1592-1 RG* 17 40 17.2372609488 -53 41 57.406007292   12.59 11.78     ~ 9 0
91 2MASS J17401754-5339066 RG* 17 40 17.5568791800 -53 39 06.828478704   14.982 14.208     ~ 8 0
92 2MASS J17401760-5342300 RG* 17 40 17.6076714144 -53 42 30.045180960     16.344     ~ 3 0
93 2MASS J17401764-5339341 RG* 17 40 17.6485643184 -53 39 34.227850428   16.581 16.182   15.601 ~ 4 0
94 [LPC2009] 12650 RG* 17 40 18.66 -53 38 53.1     16.129     ~ 2 0
95 NGC 6397 33 RG* 17 40 19.4892288432 -53 34 28.810155144   13.71 12.82     ~ 15 0
96 2MASS J17401990-5339489 RG* 17 40 19.9133032536 -53 39 49.106111616     16.010   15.16 ~ 4 0
97 [LPC2009] 13066 RG* 17 40 20.0170838184 -53 40 52.865105520     16.599     ~ 2 0
98 2MASS J17402036-5343185 RG* 17 40 20.365 -53 43 18.57     15.821   14.90 ~ 4 0
99 2MASS J17402118-5337566 RG* 17 40 21.188 -53 37 56.68   16.53 16.086     ~ 3 0
100 2MASS J17402135-5341433 RG* 17 40 21.351 -53 41 43.39     16.043   15.19 ~ 4 0
101 2MASS J17402139-5343054 RG* 17 40 21.3897894864 -53 43 05.413614852   16.50 15.988   15.12 ~ 5 0
102 2MASS J17402218-5339438 RG* 17 40 22.2014947968 -53 39 43.995417660     16.205     ~ 3 0
103 [LPC2009] 13964 RG* 17 40 22.44 -53 40 42.7     16.193     ~ 2 0
104 2MASS J17402339-5337069 RG* 17 40 23.394 -53 37 06.91     16.360     ~ 2 0
105 [LPC2009] 14412 RG* 17 40 23.4536802288 -53 37 41.596234320     16.515     ~ 2 0
106 Cl* NGC 6397 KGR 14592 RG* 17 40 23.8480114992 -53 36 40.510883376   14.338 13.696     ~ 5 0
107 TYC 8729-2535-1 RG* 17 40 24.0747126096 -53 42 52.783262496   12.37 12.21     ~ 9 0
108 2MASS J17402414-5338353 RG* 17 40 24.1557347496 -53 38 35.383123320   16.44 15.925     ~ 4 0
109 2MASS J17402463-5336253 RG* 17 40 24.636 -53 36 25.39     16.809     ~ 2 0
110 2MASS J17402472-5338455 RG* 17 40 24.726 -53 38 45.53     16.115     ~ 2 0
111 2MASS J17402528-5339274 RG* 17 40 25.2706502130 -53 39 27.499313984     15.907     ~ 3 0
112 [LPC2009] 15108 RG* 17 40 25.43 -53 41 09.0     16.235     ~ 2 0
113 [LPC2009] 15121 RG* 17 40 25.50 -53 41 40.9     16.188     ~ 2 0
114 [LPC2009] 15192 RG* 17 40 25.53 -53 38 58.6     15.973     ~ 2 0
115 2MASS J17402591-5335541 RG* 17 40 25.9130877192 -53 35 54.241073016   15.514 14.781     ~ 4 0
116 2MASS J17402631-5340519 RG* 17 40 26.3180576160 -53 40 52.056057936     16.733     ~ 2 0
117 [HKD2016] 12971 RG* 17 40 27.2421791083 -53 40 00.390537047     16.242     ~ 3 0
118 2MASS J17402767-5342161 RG* 17 40 27.6754830480 -53 42 16.190016228   16.41 15.916     ~ 3 0
119 [HKD2016] 18000165 RG* 17 40 28.0907032613 -53 38 58.462106583     15.981     ~ 3 0
120 2MASS J17402817-5337257 RG* 17 40 28.1791677792 -53 37 25.864757472   13.951 13.117     ~ 7 0
121 2MASS J17402864-5338323 RG* 17 40 28.6444798344 -53 38 32.422229340 10.44 12.81 11.771     ~ 7 0
122 2MASS J17402970-5339130 RG* 17 40 29.7089708352 -53 39 13.012699068     15.987     ~ 3 0
123 2MASS J17403068-5342258 RG* 17 40 30.6930237960 -53 42 25.918487820 10.84 12.971 12.067     ~ 11 0
124 2MASS J17403085-5337518 RG* 17 40 30.852 -53 37 51.82     16.691     ~ 2 0
125 [HKD2016] 11000063 RG* 17 40 31.5056042400 -53 41 36.929389668     16.372     ~ 3 0
126 2MASS J17403192-5341537 RG* 17 40 31.9212415200 -53 41 53.733622632   13.591 12.733     ~ 8 0
127 [HKD2016] 12364 RG* 17 40 32.6499887946 -53 39 43.567072129     16.070     ~ 3 0
128 2MASS J17403302-5338400 RG* 17 40 33.0269472408 -53 38 39.945266160     16.453     ~ 3 0
129 [LPC2009] 18376 RG* 17 40 33.37 -53 39 00.1     16.967     ~ 2 0
130 [HKD2016] 12160 RG* 17 40 34.2846045427 -53 39 52.434712103     15.958     ~ 3 0
131 [LPC2009] 19034 RG* 17 40 35.02 -53 42 00.6     16.830     ~ 2 0
132 [HKD2016] 14968 RG* 17 40 36.5521554192 -53 39 03.079999584     16.092     ~ 3 0
133 [HKD2016] 11419 RG* 17 40 38.4510673243 -53 39 54.766241882     15.904     ~ 3 0
134 2MASS J17403889-5340451 RG* 17 40 38.9057465991 -53 40 45.136970143     12.282     ~ 7 0
135 [HKD2016] 14557 RG* 17 40 39.5941888842 -53 39 29.390761981     15.535     ~ 3 0
136 2MASS J17403989-5340395 RG* 17 40 39.9005210184 -53 40 39.614527344     13.033     ~ 3 0
137 [LPC2009] 21480 RG* 17 40 40.3286261198 -53 41 25.359081599   16.68 16.103     ~ 8 0
138 [HKD2016] 6284 RG* 17 40 40.5604389016 -53 40 49.708021033     15.242     ~ 3 0
139 NGC 6397 GlC 17 40 42.09 -53 40 27.6     5.17     ~ 2103 0
140 NGC 6752 GlC 19 10 52.11 -59 59 04.4           ~ 2121 0

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