The [Y/Mg] clock works for evolved solar metallicity stars

Slumstrup, D.; Grundahl, F.; Brogaard, K.; Thygesen, A. O.; Nissen, P. E.; Jessen-Hansen, J.; Eylen, Vincent Van; Pedersen, May G.

doi:10.1051/0004-6361/201731492

Cited by 40 publications

(41 citation statements)

References 39 publications

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“…in Slumstrup et al (2017) to be 0.21 ± 0.05. With a cluster age of 650 Myr for the Hyades (Lebreton et al 2001), it leaves ǫ Tau just outside one sigma agreement with the [Y/Mg] -age relation for solar twins by Nissen et al (2017), their Fig.…”

Section: Atmospheric Parameter Analysismentioning

confidence: 93%

Asteroseismology of the Hyades red giant and planet host ϵ Tauri

Arentoft

Grundahl

White

et al. 2019

A&A

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Context. Asteroseismic analysis of solar-like stars allows us to determine physical parameters such as stellar mass, with a higher precision compared to most other methods. Even in a well-studied cluster such as the Hyades, the masses of the red giant stars are not well known, and previous mass estimates are based on model calculations (isochrones). The four known red giants in the Hyades are assumed to be clump (core-helium-burning) stars based on their positions in colour-magnitude diagrams, however asteroseismology offers an opportunity to test this assumption. Aims. Using asteroseismic techniques combined with other methods, we aim to derive physical parameters and the evolutionary stage for the planet hosting star ǫ Tau, which is one of the four red giants located in the Hyades. Methods. We analysed time-series data from both ground and space to perform the asteroseismic analysis. By combining high signalto-noise (S/N) radial-velocity data from the ground-based SONG network with continuous space-based data from the revised Kepler mission K2, we derive and characterize 27 individual oscillation modes for ǫ Tau, along with global oscillation parameters such as the large frequency separation ∆ν and the ratio between the amplitude of the oscillations measured in radial velocity and intensity as a function of frequency. The latter has been measured previously for only two stars, the Sun and Procyon. Combining the seismic analysis with interferometric and spectroscopic measurements, we derive physical parameters for ǫ Tau, and discuss its evolutionary status. Results. Along with other physical parameters, we derive an asteroseismic mass for ǫ Tau of M = 2.458 ± 0.073 M ⊙ , which is slightly lower than previous estimates, and which leads to a revised minimum mass of the planetary companion. Noting that the SONG and K2 data are non-simultaneous, we estimate the amplitude ratio between intensity and radial velocity to be 42.2 ± 2.3 ppm m −1 s, which is higher than expected from scaling relations.

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Section: Atmospheric Parameter Analysismentioning

confidence: 93%

Asteroseismology of the Hyades red giant and planet host ϵ Tauri

Arentoft

Grundahl

White

et al. 2019

A&A

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“…The observations and data reduction are presented and described in more detail in section 2 and Table A.1 of Slumstrup et al (2017). Briefly, the spectra were obtained during period 47 and 51 at the Nordic Optical Telescope (NOT) with the FIbrefed Echelle Spectrograph (FIES).…”

Section: Observationsmentioning

confidence: 99%

“…The apparent distance modulus in the V-band, µ = (m − M) V , is the difference between the apparent and absolute magnitude. The reddening and distance modulus for NGC 188 are from Meibom et al (2009) and presented in Table 1 of Slumstrup et al (2017). An empirical relation for the bolometric correction in Eq.…”

Section: Prior Informationmentioning

confidence: 99%

Systematic differences in the spectroscopic analysis of red giants

Slumstrup

Grundahl

Aguirre

et al. 2019

A&A

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Aims.A spectroscopic analysis of stellar spectra can be carried out using different approaches; different methods, line lists, atmospheric models, atomic parameters, solar abundances etc. The resulting atmospheric parameters from these choices can vary beyond the quoted uncertainties in the literature. Here we characterize these differences by systematically comparing some of the commonly adopted ingredients; line lists, equivalent width measurements and atomic parameters. Methods. High resolution and high signal-to-noise (S/N) spectroscopic data of one helium-core-burning red giant star in each of the three open clusters, NGC 6819, M67 and NGC 188 have been obtained with the FIES spectrograph at the Nordic Optical Telescope. The M67 target has been used to benchmark the analysis, as it is a well studied cluster with asteroseismic data from the K2 mission. For the other two clusters we have obtained higher quality data than what had been analyzed before, which allows us establish their chemical composition more securely. Using a line by line analysis, we tested several different combinations of line lists and programs to measure equivalent widths of stellar absorption lines to characterize systematic differences within the same spectroscopic method. Results. The obtained parameters for the benchmark star in M67 vary up to ∼170 K in effective temperature, ∼0.4 dex in log g and ∼0.25 dex in [Fe/H] between the different tested setups. Using the combination of equivalent width measurement program and line list that best reproduce the inferred surface gravity from asteroseismology, we determined the atmospheric parameters for the three stars and securely established the chemical composition of NGC 6819 to be close to solar, [Fe/H]=-0.02±0.01 dex. Conclusions. We have highlighted the significantly different results obtained with different combinations of line lists, programs and atomic parameters. The results emphasize the importance of benchmark stars studied with several different methods to anchor spectroscopic analyses.

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“…It should, however, be noted that the tight [Y/Mg]-age relation found in these papers and in the present work refers to stars with metallicities close to solar. Feltzing et al (2017) Slumstrup et al (2017) suggests that the [Y/Mg]-age relation is also valid outside the solar neighbourhood, but this should be verified for a larger sample of distant stars.…”

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confidence: 99%

High-precision abundances of elements inKeplerLEGACY stars

Nissen

Aguirre

Christensen‐Dalsgaard

et al. 2017

A&A

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Context. A previous study of solar twin stars has revealed the existence of correlations between some abundance ratios and stellar age providing new knowledge about nucleosynthesis and Galactic chemical evolution. Aims. High-precision abundances of elements are determined for stars with asteroseismic ages in order to test the solar twin relations. Methods. HARPS-N spectra with signal-to-noise ratios S /N > ∼ 250 and MARCS model atmospheres were used to derive abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, and Y in ten stars from the Kepler LEGACY sample (including the binary pair 16 Cyg A and B) selected to have metallicities in the range −0.15 < [Fe/H] < +0.15 and ages between 1 and 7 Gyr. Stellar gravities were obtained from seismic data and effective temperatures were determined by comparing non-LTE iron abundances derived from Fe i and Fe ii lines. Available non-LTE corrections were also applied when deriving abundances of the other elements.

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The [Y/Mg] clock works for evolved solar metallicity stars

Cited by 40 publications

References 39 publications

Asteroseismology of the Hyades red giant and planet host ϵ Tauri

Asteroseismology of the Hyades red giant and planet host ϵ Tauri

Systematic differences in the spectroscopic analysis of red giants

High-precision abundances of elements inKeplerLEGACY stars

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