2023A&A...671A..53M


Query : 2023A&A...671A..53M

2023A&A...671A..53M - Astronomy and Astrophysics, volume 671A, 53 (2023/3-1)

Red horizontal branch stars: An asteroseismic perspective.

MATTEUZZI M., MONTALBAN J., MIGLIO A., VRARD M., CASALI G., STOKHOLM A., TAILO M., BALL W.H., VAN ROSSEM W.E. and VALENTINI M.

Abstract (from CDS):

Robust age estimates of red giant stars are now possible thanks to the precise inference of their mass based on asteroseismic constraints. However, there are cases where such age estimates can be highly precise yet very inaccurate. An example is giants that have undergone mass loss or mass transfer events that have significantly altered their mass. In this context, stars with 'apparent' ages significantly higher than the age of the Universe are candidates for stripped stars, or stars that have lost more mass than expected, most likely via interactions with a companion star or because of the poorly understood mass-loss mechanism along the red-giant branch. In this work we identify examples of such objects among red giants observed by Kepler, both at low ([Fe/H] ≲ -0.5) and solar metallicity. By modelling their structure and pulsation spectra, we find a consistent picture that confirms that they are indeed low-mass objects consisting of a He core of ≈0.5 M and an envelope of ≈0.1 - 0.2 M. Moreover, we find that these stars are characterised by a rather extreme coupling (q ≳ 0.4) between the pressure-mode and gravity-mode cavities, one that is much higher than the typical value for red clump stars, thus providing a direct seismic signature of their peculiar structure. The complex pulsation spectra of these objects, if observed with sufficient frequency resolution, hold detailed information about the structural properties of likely products of mass stripping and can hence potentially shed light on their formation mechanism. On the other hand, our tests highlight the difficulties associated with reliably measuring the large frequency separation, especially in shorter datasets, which impacts the reliability of the inferred masses and ages of low-mass red clump stars with, for example, K2 or TESS data.

Abstract Copyright: © The Authors 2023

Journal keyword(s): asteroseismology - stars: evolution - stars: fundamental parameters - stars: horizontal-branch - stars: interiors - stars: mass-loss

Simbad objects: 16

goto Full paper

goto View the references in ADS

Number of rows : 16
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1856 0
2 UCAC4 683-066076 HB* 18 46 49.3908268416 +46 26 26.797951464   14.665 13.855 13.687   G3V 6 0
3 TYC 3545-117-1 HB* 19 00 14.4332258256 +48 36 49.637719764   11.60 10.94     ~ 15 0
4 UCAC4 644-063932 * 19 00 29.7202472351 +38 46 24.835320158       13.092   ~ 3 0
5 UCAC4 640-063699 HB* 19 04 26.2515332976 +37 51 32.495385924       12.448   G3V 6 0
6 UCAC4 643-066363 HB* 19 07 35.8864709424 +38 34 56.312726628       12.266   F8V 4 0
7 UCAC4 708-064014 RG* 19 12 28.3542670080 +51 26 51.355738104   13.901 12.946 12.830   F8V 9 0
8 KOI-1054 HB* 19 14 43.8146867616 +41 18 26.427314124           ~ 31 0
9 TYC 3542-2568-1 HB* 19 14 57.0590298144 +45 48 04.668929676   13.18 11.80     ~ 5 0
10 NGC 6791 2042 RG* 19 20 43.6819494240 +37 46 41.694843468   16.428 14.985   13.502 ~ 21 0
11 TYC 3138-562-1 HB* 19 22 57.7117384368 +40 26 30.682616136   12.49 11.66     ~ 20 0
12 TYC 2666-1391-1 HB* 19 24 26.1483490176 +36 48 47.839873752   11.61 10.54     ~ 27 0
13 2MASS J19332527+4905240 HB* 19 33 25.2745261440 +49 05 23.962279092           K2IIIb 21 0
14 UCAC4 675-074334 Pe* 19 34 53.4204635088 +44 52 06.238475472   13.802 12.893 12.694   ~ 11 0
15 2MASS J19411367+4003382 HB* 19 41 13.6692983051 +40 03 38.196221649     13.59   12.31 ~ 54 0
16 NGC 6819 OpC 19 41 18.5 +40 11 24   8.21 7.3     ~ 635 0

To bookmark this query, right click on this link: simbad:objects in 2023A&A...671A..53M and select 'bookmark this link' or equivalent in the popup menu