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 - 2021
#notes
1 G 267-44 PM* 00 10 43.0496022276 -28 58 13.774097300   14.30 13.32     ~ 4 0
2 HD 1087 PM* 00 15 03.2780980265 -27 30 08.939179400   10.13 9.16     K1IV 9 0
3 HD 1196 PM* 00 16 10.3176937716 -27 46 41.952875463   9.99 9.33     G5V 19 0
4 EGM 79 PM* 00 19 45.4748992042 -22 33 10.858380078   14.497 13.022 12.589   ~ 8 0
5 CD-25 113 PM* 00 22 07.8579302538 -24 38 01.151955823   13.39 12.30     ~ 9 0
6 NGC 714 GiG 01 53 29.652 +36 13 16.80   13.9       ~ 52 0
7 NGC 752 OpC 01 57 41 +37 47.1           ~ 566 0
8 NGC 1817 OpC 05 12 15 +16 41.4           ~ 157 0
9 Cl Berkeley 17 OpC 05 20 37 +30 35.4           ~ 142 0
10 NGC 2141 OpC 06 02 55 +10 26.8   10.43 9.4     ~ 119 0
11 Cl Berkeley 29 OpC 06 53 04.2 +16 55 39   14.3       ~ 147 0
12 NAME Saurer A Cluster OpC 07 20.9 +01 48           ~ 58 0
13 NGC 2682 OpC 08 51 18 +11 48.0           ~ 2114 0
14 NGC 3680 OpC 11 25 38 -43 14.6   8.40 7.6     ~ 295 0
15 NGC 3680 60 * 11 26 20.7065618739 -43 13 07.466176954   14.99 14.36     ~ 25 0
16 Cl Collinder 261 OpC 12 38 11.5 -68 22 01     10.7     ~ 164 0
17 NGC 4756 BiC 12 52 52.621 -15 24 47.85   13   11.80   ~ 63 0
18 Cl* NGC 5822 MMU 224 * 15 03 22.8543979137 -54 26 32.862528265 12.579 11.52 10.84     ~ 16 0
19 NGC 5822 87 * 15 03 49.4166121059 -54 20 10.597900783 12.61 11.88 10.84 10.285   ~ 21 0
20 NGC 5822 OpC 15 04 28 -54 23.4           ~ 180 0
21 Cl* NGC 5822 TA 11014 * 15 04 35.3020444210 -54 17 37.544667475 16.334 15.182 14.423 14.51   ~ 6 0
22 Cl* NGC 5822 TA 11003 * 15 04 54.2483048273 -54 15 48.385740231   15.43 14.66 14.42 13.90 ~ 5 0
23 NGC 5822 157 * 15 05 31.1443670928 -54 26 20.134873476 12.72 11.97 10.93     ~ 18 0
24 Cl* IC 4651 MEI 6081 * 17 24 31.8192985679 -49 59 08.591581971           ~ 12 0
25 IC 4651 95 * 17 24 36.8673353386 -49 55 54.691175424   13.473 12.937     ~ 12 0
26 Cl* IC 4651 AMC 4226 * 17 24 43.4558015480 -50 01 01.274579314           ~ 15 0
27 IC 4651 17 * 17 24 48.0970124432 -49 55 47.356510983   15.250 14.545     ~ 13 0
28 IC 4651 OpC 17 24 49 -49 56.0           ~ 322 0
29 IC 4651 65 * 17 24 59.9717265502 -49 53 07.832280641       14.41   ~ 13 0
30 NGC 6475 OpC 17 53 51 -34 47.6           ~ 347 0
31 BD+05 3829 * 18 37 05.2146447935 +05 17 31.620772375 10.58 10.93 9.83     G5 31 0
32 BD+05 3833 * 18 37 20.7739544039 +05 53 43.108019046 10.08 10.43 9.46     G0 19 0
33 IC 4756 368 * 18 37 37.6955753667 +05 31 00.419384268 14.60 14.23 13.38     ~ 5 0
34 Cl* IC 4756 HER 165 * 18 38 18.8409296610 +05 31 02.861915231   14.31 13.591 13.110 12.650 G5V 8 0
35 IC 4756 OpC 18 38 31.2 +05 29 24           ~ 205 0
36 IC 4756 425 * 18 38 47.2849484428 +05 16 24.979759932 14.61 14.24 13.48 13.70   G2V 7 0
37 BD+05 3882 * 18 39 17.8752632698 +05 13 48.734790627 10.09 10.37 9.36     G0 31 0
38 IC 4765 BiC 18 47 18.150 -63 19 52.14   12.33 11.36 10.53 10.75 ~ 76 2
39 NGC 6939 OpC 20 31 30 +60 39.7   8.85 7.8     ~ 139 0
40 NGC 7789 OpC 23 57 24 +56 42.5   7.68 6.7     ~ 467 0

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2021.09.22-13:28:53

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