2017A&A...598A..86D


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.08CEST03:14:19

2017A&A...598A..86D - Astronomy and Astrophysics, volume 598A, 86-86 (2017/2-1)

First determination of s-process element abundances in pre-main sequence clusters Y, Zr, La, and Ce in IC 2391, the Argus association, and IC 2602.

D'ORAZI V., DE SILVA G.M. and MELO C.F.H.

Abstract (from CDS):

Context. Several high-resolution spectroscopic studies have provided compelling observational evidence that open clusters display a decreasing trend of their barium abundances as a function of the cluster's age. Young clusters (ages≤200Myr) exhibit significant enhancement in the [Ba/Fe] ratios, at variance with solar-age clusters where the Ba content has been found to be [Ba/Fe]∼0dex. Different viable solutions have been suggested in the literature; nevertheless, a conclusive interpretation of such a peculiar trend has not been found. Interestingly, it is debated whether the other species produced with Ba via s-process reactions follow the same trend with age.
Aims. Pre-main sequence clusters (~=10-50Myr) show the most extreme behaviour in this respect: their [Ba/Fe] ratios can reach 0.65dex, which is higher than the solar value by a factor of four. Crucially, there are no investigations of the other s-process species for these young stellar populations. In this paper we present the first determination of Y, Zr, La, and Ce in clusters IC 2391, IC 2602, and the Argus association. The main objective of our work is to ascertain whether these elements reveal the same enhancement as Ba.
Methods. We have exploited high-resolution, high signal-to-noise spectra in order to derive abundances for Y, Zr, La, and Ce via spectral synthesis calculations. Our sample includes only stars with very similar atmospheric parameters so that internal errors due to star-to-star inhomogeneity are negligible. The chemical analysis was carried out in a strictly differential way, as done in all our previous investigations, to minimise the impact of systematic uncertainties.
Results. Our results indicate that, at variance with Ba, all the other s-process species exhibit a solar scaled pattern; these clusters confirm a similar trend discovered in the slightly older local associations (e.g. AB Doradus, Carina-Near), where only Ba exhibit enhanced value with all other s-process species being solar. We have discussed several possible explanations such as chromospheric effects, departures from the LTE approximation, or the activation of a different nucleosynthesis chain. We cannot currently provide the definite answer to this question and future investigations from theoretical and observational perspectives are sorely needed.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: solar-type - stars: abundances - open clusters and associations: individual: IC 2391 - open clusters and associations: individual: Argus - open clusters and associations: individual: IC 2602

Simbad objects: 17

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Number of rows : 17

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NGC 188 OpC 00 48 26 +85 15.3           ~ 813 0
2 CD-28 3434 * 06 47 37.6814871563 -28 58 08.235787248   11.45 9.99     K0V 9 0
3 Cl* IC 2391 D 41 * 08 37 51.5682313314 -53 45 45.785059586   12.15 11.39 11.23   G8 17 0
4 CD-52 2467 * 08 38 22.9094400997 -52 56 48.038542116   11.61 10.93 10.81   ~ 19 0
5 IC 2391 OpC 08 40 32 -53 02.0           ~ 714 0
6 Cl* IC 2391 SMY 23 * 08 40 49.1006933615 -53 37 45.362061017   11.91 11.15 10.84   G6 22 0
7 NGC 2682 OpC 08 51 18 +11 48.0           ~ 2032 0
8 CD-39 5833 * 09 47 19.8551930281 -40 03 09.843391210   11.57 10.89     K0V 17 0
9 IC 2602 OpC 10 42 58 -64 24.0           ~ 549 0
10 V* V558 Car BY* 10 44 06.8105449584 -63 59 35.056780744   11.75       G4 27 0
11 V* V559 Car BY* 10 44 22.5514609452 -64 15 30.116315015   11.61       G0 30 0
12 NAME Ursa Major Moving Group MGr 12 32 +57.0           ~ 378 2
13 * e Vir PM* 13 16 46.5161591991 +09 25 26.967205938   5.81   4.8   G0V 502 1
14 V* V4334 Sgr NL* 17 52 32.69 -17 41 08.0   12.01       F2Ia 329 0
15 NGC 6791 OpC 19 20 53 +37 46.3   10.52 9.5     ~ 869 0
16 NAME Argus Association As* ~ ~           ~ 162 0
17 NAME AB Dor Moving Group MGr ~ ~           ~ 355 0

    Equat.    Gal    SGal    Ecl

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2020.07.08-03:14:19

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