2010A&A...515A..28P


Query : 2010A&A...515A..28P

2010A&A...515A..28P - Astronomy and Astrophysics, volume 515, A28-28 (2010/6-1)

Abundances and physical parameters for stars in the open clusters NGC 5822 and IC 4756.

PACE G., DANZIGER J., CARRARO G., MELENDEZ J., FRANCOIS P., MATTEUCCI F. and SANTOS N.C.

Abstract (from CDS):

Classical chemical analyses may be affected by systematic errors that would cause observed abundance differences between dwarfs and giants. For some elements, however, the abundance difference could be real. We address the issue by observing 2 solar-type dwarfs in NGC 5822 and 3 in IC 4756, and comparing their composition with that of 3 giants in either of the aforementioned clusters. We determine iron abundance and stellar parameters of the dwarf stars, and the abundances of calcium, sodium, nickel, titanium, aluminium, chromium, silicon, and oxygen for both the giants and dwarfs. For the dwarfs, we also estimate the rotation velocities, and and lithium abundances. We improve the cluster parameter estimates (distance, age, and reddening) by comparing existing photometry with new isochrones. We acquired UVES high-resolution, of high signal-to-noise ratio (S/N) spectra. The width of the cross correlation profiles was used to measure rotation velocities. For abundance determinations, the standard equivalent width analysis was performed differentially with respect to the Sun. For lithium and oxygen, we derived abundances by comparing synthetic spectra with observed line features. We find an iron abundance for dwarf stars equal to solar to within the margins of error for IC 4756, and slightly above for NGC 5822 ([Fe/H]=0.01 and 0.05dex respectively). The 3 stars in NGC 4756 have lithium abundances between Log N(Li)≃2.6 and 2.8dex, the two stars in NGC 5822 have Log N(Li)≃2.8 and 2.5, respectively. For sodium, silicon, and titanium, we show that abundances of giants are significantly higher than those of the dwarfs of the same cluster (about 0.15, 0.15, and 0.35dex). Other elements may also undergo enhancement, but all within 0.1dex. Indications of much stronger enhancements can be found using literature data. But artifacts of the analysis may be partly responsible for this.

Abstract Copyright:

Journal keyword(s): open clusters and associations: individual: NGC 5822 - open clusters and associations: individual: IC 4756 - stars: abundances - stars: rotation

VizieR on-line data: <Available at CDS (J/A+A/515/A28): table2.dat>

Simbad objects: 40

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Number of rows : 40
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 G 267-44 PM* 00 10 43.0498264104 -28 58 13.772128908   14.30 13.32     ~ 4 0
2 HD 1087 PM* 00 15 03.2779636248 -27 30 08.938939392   10.13 9.16     K1IV 9 0
3 HD 1196 PM* 00 16 10.3176702528 -27 46 41.952203760   9.99 9.33     G5V 20 0
4 EGM 79 PM* 00 19 45.4742301552 -22 33 10.858070592   14.497 13.022 12.589   ~ 11 0
5 CD-25 113 PM* 00 22 07.8580507560 -24 38 01.149930492   13.39 12.30     ~ 11 0
6 NGC 714 GiG 01 53 29.6437601928 +36 13 16.563840240   13.9       ~ 53 0
7 NGC 752 OpC 01 56 54 +37 47.6           ~ 608 0
8 NGC 1817 OpC 05 12 33 +16 41.8           ~ 171 0
9 Cl Berkeley 17 OpC 05 20 31 +30 34.4           ~ 162 0
10 NGC 2141 OpC 06 02 56 +10 27.1           ~ 136 0
11 Cl Berkeley 29 OpC 06 53 04.2 +16 55 39   14.3       ~ 167 0
12 NAME Saurer A Cluster OpC 07 20.9 +01 48           ~ 64 0
13 NGC 2682 OpC 08 51 23 +11 48.8           ~ 2234 0
14 NGC 3680 OpC 11 25 34 -43 14.4   8.40 7.6     ~ 309 0
15 NGC 3680 60 * 11 26 20.7065904912 -43 13 07.467128544   14.99 14.36     ~ 28 0
16 Cl Collinder 261 OpC 12 38 05 -68 22.6     10.7     ~ 182 0
17 NGC 4756 BiC 12 52 52.621 -15 24 47.85   13   11.80   ~ 64 0
18 Cl* NGC 5822 MMU 224 * 15 03 22.8542829960 -54 26 32.861730804 12.579 11.52 10.84     ~ 18 0
19 NGC 5822 87 * 15 03 49.4167331160 -54 20 10.602411612 12.61 11.88 10.84 10.285   ~ 24 0
20 NGC 5822 OpC 15 04 12 -54 22.0           ~ 197 0
21 Cl* NGC 5822 TA 11014 * 15 04 35.3020493712 -54 17 37.545141408 16.334 15.182 14.423 14.51   ~ 8 0
22 Cl* NGC 5822 TA 11003 * 15 04 54.2483851032 -54 15 48.387190356   15.43 14.66 14.42 13.90 ~ 7 0
23 NGC 5822 157 * 15 05 31.1445680040 -54 26 20.134965516 12.72 11.97 10.93     ~ 20 0
24 Cl* IC 4651 MEI 6081 * 17 24 31.8192107640 -49 59 08.591260884           ~ 14 0
25 IC 4651 95 * 17 24 36.8673528288 -49 55 54.692199984   13.473 12.937     ~ 14 0
26 Cl* IC 4651 AMC 4226 * 17 24 43.4557289976 -50 01 01.275456828           ~ 17 0
27 IC 4651 17 * 17 24 48.0970940376 -49 55 47.356824144   15.250 14.545     ~ 13 0
28 IC 4651 OpC 17 24 51 -49 55.0           ~ 339 0
29 IC 4651 65 * 17 24 59.9718574488 -49 53 07.834464996       14.41   ~ 16 0
30 NGC 6475 OpC 17 53 47 -34 50.5           ~ 365 0
31 BD+05 3829 * 18 37 05.2144598832 +05 17 31.621063920 10.58 10.93 9.83     G5 35 0
32 BD+05 3833 * 18 37 20.7739949622 +05 53 43.109227904 10.08 10.43 9.46     G0 21 0
33 IC 4756 368 * 18 37 37.6956654408 +05 31 00.419299212 14.60 14.23 13.38     ~ 5 0
34 Cl* IC 4756 HER 165 * 18 38 18.8409758256 +05 31 02.863451964   14.31 13.591 13.110 12.650 G5V 8 0
35 IC 4756 OpC 18 38 31.2 +05 29 24           ~ 226 0
36 IC 4756 425 * 18 38 47.2849416456 +05 16 24.979311768 14.61 14.24 13.48 13.70   G2V 9 0
37 BD+05 3882 * 18 39 17.8751122128 +05 13 48.737856648 10.09 10.37 9.36     G0 33 0
38 IC 4765 BiC 18 47 18.150 -63 19 52.14   12.33 11.36 10.53 10.75 ~ 82 2
39 NGC 6939 OpC 20 31 40 +60 39.2   8.85 7.8     ~ 153 0
40 NGC 7789 OpC 23 57 20 +56 43.6   7.68 6.7     ~ 497 0

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2023.02.04-08:58:30

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