2018A&A...616A.104K


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST14:45:27

2018A&A...616A.104K - Astronomy and Astrophysics, volume 616A, 104-104 (2018/8-1)

Non-linear seismic scaling relations.

KALLINGER T., BECK P.G., STELLO D. and GARCIA R.A.

Abstract (from CDS):


Context. In recent years the global seismic scaling relations for the frequency of maximum power, νmax∝g/Teff1/2, and for the large frequency separation, Δν∝(ρ{bar})1/2, have drawn attention in various fields of astrophysics. This is because these relations can be used to estimate parameters, such as the mass and radius of stars that show solar-like oscillations. With the exquisite photometry of Kepler, the uncertainties in the seismic observables are small enough to estimate masses and radii with a precision of only a few per cent. Even though this seems to work quite well for main-sequence stars, there is empirical evidence, mainly from studies of eclipsing binary systems, that the seismic scaling relations systematically overestimate the mass and radius of red giants by about 15% and 5%, respectively. Various model-based corrections of the Δν-scaling reduce the problem but do not solve it.
Aims. Our goal is to define revised seismic scaling relations that account for the known systematic mass and radius discrepancies in a completely model-independent way.
Methods. We use probabilistic methods to analyse the seismic data and to derive non-linear scaling relations based on a sample of six red giant branch (RGB) stars that are members of eclipsing binary systems and about 60 red giants on the RGB as well as in the core-helium burning red clump (RC) in the two open clusters NGC 6791 and NGC 6819.
Results. We re-examine the global oscillation parameters of the giants in the binary systems in order to determine their seismic fundamental parameters and we find them to agree with the dynamic parameters from the literature if we adopt non-linear scalings. We note that a curvature and glitch corrected Δνcor should be preferred over a local or average value of Δν. We then compare the observed seismic parameters of the cluster giants to those scaled from independent measurements and find the same non-linear behaviour as for the eclipsing binaries. Our final proposed scaling relations are based on both samples and cover a broad range of evolutionary stages from RGB to RC stars: g/Teff1/2=(νmaxmax,☉)1.0075±0.0021 and (ρ{bar})1/2=(Δνcor/Δνcor,☉)[η-(0.0085±0.0025)log2(Δνcor/Δνcor,☉)]–1 where g, Teff, and ρ{bar} are in solar units, νmax,☉=3140±5µHz and Δνcor,☉=135.08±0.02µHz, and η is equal to one in the case of RGB stars and 1.04±0.01 for RC stars.
Conclusions. A direct consequence of these new scaling relations is that the average mass of stars on the ascending giant branch reduces to 1.10±0.03M in NGC 6791 and 1.45±0.06M in NGC 6819, allowing us to revise the clusters' distance modulus to 13.11±0.03 and 11.91±0.03mag, respectively. We also find strong evidence that both clusters are significantly older than concluded from previous seismic investigations.

Abstract Copyright: © ESO 2018

Journal keyword(s): stars: fundamental parameters - stars: oscillations - stars: late-type - stars: interiors - open clusters and associations: individual: NGC 6819 - open clusters and associations: individual: NGC 6791

Simbad objects: 18

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Number of rows : 18

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 TYC 3130-2385-1 Al* 18 48 38.0889273281 +44 29 09.853475372   12.18 11.33     ~ 42 0
2 2MASS J19074937+4656118 RG* 19 07 49.3737222047 +46 56 11.866115223   11.48 10.39     ~ 22 0
3 NGC 6791 OpC 19 20 53 +37 46.3   10.52 9.5     ~ 869 0
4 KIC 5786154 Al* 19 21 01.4108245931 +41 01 04.924141502           K2III 21 0
5 KIC 7037405 RG* 19 31 54.2896527425 +42 32 51.638842250           ~ 23 0
6 HD 185351 PM* 19 36 37.9763032863 +44 41 41.760069923   6.109 5.169     G8.5IIIbFe-0.5 126 0
7 KIC 4663623 RG* 19 36 47.6957469626 +39 45 28.737057288           ~ 14 0
8 KIC 5111940 RG* 19 40 49.6541282423 +40 14 31.281329337     13.370   12.09 G5III 26 0
9 KIC 5023931 RG* 19 40 57.0426476518 +40 10 06.814669597     13.320   12.00 ~ 19 0
10 NGC 6819 665 Al* 19 40 57.8290137903 +40 09 27.378973562   15.82 15.17   14.38 ~ 21 0
11 KIC 5024447 Al* 19 41 16.8477150692 +40 07 27.520998139   15.714 15.090   14.34 ~ 18 0
12 NGC 6819 OpC 19 41 18 +40 11.2   8.21 7.3     ~ 465 0
13 KIC 9163796 EB* 19 41 20.9935050896 +45 30 17.197057636   10.67 9.82     G5 13 0
14 NGC 6819 259 Al* 19 41 33.9266701033 +40 13 00.248112786   16.356 15.651   14.774 ~ 30 1
15 KIC 7377422 Al* 19 43 43.3026296842 +42 57 04.279366998           ~ 16 0
16 KIC 9540226 Al* 19 48 08.1619895492 +46 11 54.562350288   12.75 12.44     G6V 33 0
17 KOI-7606 RG* 19 54 50.3554741074 +46 49 58.914505187           G6V 28 0
18 HD 190585 EB* 20 03 48.3210976468 +45 36 14.803519667   10.74 9.65     K2 32 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-14:45:27

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