Kepler red-clump stars in the field and in open clusters: constraints on core mixing
Date Issued
2017
Author(s)
Bossini, D.
•
Miglio, A.
•
Salaris, M.
•
Vrard, M.
•
•
Mosser, B.
•
Montalbán, J.
•
•
Noels, A.
•
Bressan, A.
•
•
Tayar, J.
Abstract
Convective mixing in helium-core-burning (HeCB) stars is one of the outstanding issues in stellar modelling. The precise asteroseismic measurements of gravity-mode period spacing (∆Π1) have opened the door to detailed studies of the near-core structure of such stars, which had not been possible before. Here, we provide stringent tests of various core-mixing scenarios against the largely unbiased population of red-clump stars belonging to the old-open clusters monitored by Kepler, and by coupling the updated precise inference on ∆Π1 in thousands of field stars with spectroscopic constraints. We find that models with moderate overshooting successfully reproduce the range observed of ∆Π1 in clusters. In particular, we show that there is no evidence for the need to extend the size of the adiabatically stratified core, at least at the beginning of the HeCB phase. This conclusion is based primarily on ensemble studies of ∆Π1 as a function of mass and metallicity. While ∆Π1 shows no appreciable dependence on the mass, we have found a clear dependence of ∆Π1 on metallicity, which is also supported by predictions from models.
Volume
469
Issue
4
Start page
4718
Issn Identifier
0035-8711
Ads BibCode
2017MNRAS.469.4718B
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
1705.03077.pdf
Size
457.13 KB
Format
Adobe PDF
Checksum (MD5)
90b15411b8c061b084c0d1be6e5a171b
Loading...
Name
stx1135.pdf
Description
PDF editoriale
Size
654.81 KB
Format
Adobe PDF
Checksum (MD5)
6f460b48d83bad7e28c23e885ef243e6