2007A&A...469..163R


Query : 2007A&A...469..163R

2007A&A...469..163R - Astronomy and Astrophysics, volume 469, 163-172 (2007/7-1)

Tracing mixing in stars: new beryllium observations of the open clusters NGC 2516, Hyades, and M 67.

RANDICH S., PRIMAS F., PASQUINI L., SESTITO P. and PALLAVICINI R.

Abstract (from CDS):

Determinations of beryllium abundance in stars, together with lithium, provide a key tool to investigate the so far poorly understood extra-mixing processes at work in stellar interiors. We measured Be in three open clusters, complementing existing Be surveys, and aiming at gathering a more complete empirical scenario of the evolution of Be as a function of stellar age and temperature. We analyzed VLT/UVES spectra of members of NGC 2516, the Hyades, and M 67 to determine their Be and Li abundances. In the first two clusters we focused on stars cooler than 5400K, while the M 67 sample includes stars warmer than 6150K, as well as two subgiants and two blue stragglers. We also computed the evolution of Be for a 0.9M star based on standard evolutionary models. We find different behaviours for stars in different temperature bins and ages. Stars warmer than 6150K show Be depletion and follow a Be vs. Li correlation, while Be is undepleted in stars in the ∼6150-5600K range. NGC 2516 members cooler than 5400K have not depleted any Be, while older Hyades of similar temperature show some depletion. Be is severely depleted in the subgiants and blue stragglers. The results for warm stars are in agreement with those of previous studies, supporting the hypothesis that mixing in this temperature regime is driven by rotation. The same holds for the two subgiants that have evolved from the ``Li gap''. This mechanism is instead not the dominant one for solar-type stars. We show that Be depletion of cool Hyades cannot simply be explained by the effect of increasing depth of the convective zone. Finally, the different Be content of the two blue stragglers suggests that they have formed by two different processes (i.e., collisions vs. binary merging).

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: evolution - stars: interiors - open clusters and associations: individual: M 67 - open clusters and associations: individual: NGC 2516 - open clusters and associations: individual: Hyades

Simbad objects: 25

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Number of rows : 25
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 Cl Melotte 22 OpC 03 46 24 +24 06.8           ~ 3208 0
2 V* V984 Tau BY* 04 16 33.4775734800 +21 54 26.882025156   9.944 9.125     ~ 159 0
3 Cl Melotte 25 OpC 04 29 47 +16 56.9           ~ 2861 0
4 HD 28545 SB* 04 30 34.8766762656 +15 44 02.372601156   9.720 8.84 9.03   K0 79 1
5 HD 284574 PM* 04 40 05.8433176920 +23 18 16.365681612   10.211 9.402     K0 85 0
6 HD 32347 PM* 05 03 07.6577118384 +13 43 50.412591984   9.372 8.596 8.182 7.810 K0 105 0
7 NGC 2168 OpC 06 09 05 +24 20.2           ~ 510 0
8 Cl* NGC 2516 JJT 7 * 07 57 20.7551436696 -60 46 44.408343072   15.087 14.184   13.177 ~ 14 0
9 Cl* NGC 2516 JJT 11 * 07 57 31.5394338168 -60 42 10.788334848   15.225 14.287   13.280 ~ 15 0
10 Cl* NGC 2516 DAC 213 SB* 07 57 55.4826448800 -60 43 20.646461028 15.29 14.92 14.04   12.994 ~ 12 0
11 NGC 2516 OpC 07 58 06 -60 48.0           ~ 652 0
12 Cl* NGC 2516 JJT 26 * 07 58 40.7915706888 -60 41 53.315330820   14.369 13.590   12.701 ~ 16 0
13 IC 2391 OpC 08 41 10 -52 59.5           ~ 774 0
14 CPD-52 1614 SB* 08 42 46.6075101288 -53 01 01.341693984   10.7 10.3     ~ 31 0
15 NGC 2682 75 SB* 08 51 08.6383931784 +11 46 11.814942540 14.074 13.99 13.383   12.741 ~ 39 0
16 NGC 2682 106 V* 08 51 17.3469363072 +11 47 00.664213272 13.671 13.638 13.069   12.393 ~ 59 0
17 NGC 2682 115 V* 08 51 18.5413189200 +11 49 21.513324180 13.309 13.26 12.645 12.274 11.924 F9IV 74 0
18 NGC 2682 124 BS* 08 51 19.9070240880 +11 47 00.441178944 12.576 12.59 12.117 11.848 11.564 F5IV 80 0
19 NGC 2682 127 V* 08 51 20.1237509496 +11 46 41.751494436 13.336 13.32 12.776   12.08 ~ 77 0
20 NGC 2682 128 * 08 51 20.3300020320 +11 45 52.481465496 13.782 13.72 13.244   12.445 ~ 59 0
21 NGC 2682 129 * 08 51 20.5508066664 +11 46 04.890109584 13.826 13.75 13.308   12.490 ~ 56 0
22 NGC 2682 130 V* 08 51 20.5734927984 +11 46 16.412199564 13.346 13.34 12.950   12.30 G: 58 0
23 NGC 2682 140 Ro* 08 51 22.0511842656 +11 46 41.010219552 13.811 13.797 13.189 12.834 12.496 ~ 65 0
24 NGC 2682 OpC 08 51 23 +11 48.8           ~ 2191 0
25 NGC 2682 226 * 08 51 44.0075287632 +11 46 24.535277112 13.749 13.549 12.790   11.928 G0 61 0

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2022.08.15-14:36:34

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