2016A&A...594L...3L


Query : 2016A&A...594L...3L

2016A&A...594L...3L - Astronomy and Astrophysics, volume 594, L3-3 (2016/10-1)

The age-mass-metallicity-activity relation for solar-type stars: comparisons with asteroseismology and the NGC 188 open cluster.

LORENZO-OLIVEIRA D., PORTO DE MELLO G.F. and SCHIAVON R.P.

Abstract (from CDS):

Context. The Mount Wilson CaII index log(R'HK) is the accepted standard metric of calibration for the chromospheric activity versus age relation for FGK stars. Recent results claim its inability to discern activity levels, and thus ages, for stars older than ∼2Gyr, which would severely hamper its application to date disk stars older than the Sun.
Aims. We present a new activity-age calibration of the Mt. Wilson index that explicitly takes mass and [Fe/H] biases into account; these biases are implicit in samples of stars selected to have precise ages, which have so far not been appreciated.
Methods. We show that these selection biases tend to blur the activity-age relation for large age ranges. We calibrate the Mt. Wilson index for a sample of field FGK stars with precise ages, covering a wide range of mass and [Fe/H] , augmented with data from the Pleiades, Hyades, M 67 clusters, and the Ursa Major moving group.
Results. We further test the calibration with extensive new Gemini/GMOS log ()R'HK) data of the old, solar [Fe/H] clusters, M 67 and NGC 188. The observed NGC 188 activity level is clearly lower than M 67. We correctly recover the isochronal age of both clusters and establish the viability of deriving usable chromospheric ages for solar-type stars up to at least ∼6Gyr, where average errors are ∼0.14dex provided that we explicitly account for the mass and [Fe/H] dimensions. We test our calibration against asteroseismological ages, finding excellent correlation (ρ=+0.89). We show that our calibration improves the chromospheric age determination for a wide range of ages, masses, and metallicities in comparison to previous age-activity relations.

Abstract Copyright: © ESO, 2016

Journal keyword(s): stars: late-type - stars: activity - stars: chromospheres - open clusters and associations: individual: M 67 - open clusters and associations: individual: NGC 188

Simbad objects: 8

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Number of rows : 8
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 NGC 188 OpC 00 47 11.5 +85 14 38           ~ 909 0
2 Cl Melotte 22 OpC 03 46 24.2 +24 06 50           ~ 3387 0
3 Cl Melotte 25 OpC 04 29 47.3 +16 56 53           ~ 3018 0
4 NGC 2682 OpC 08 51 23.0 +11 48 50           ~ 2311 0
5 NAME UMa Region reg 11 00 +50.0           ~ 326 0
6 NAME Ursa Major Moving Group MGr 12 32 +57.0           ~ 433 2
7 NGC 6811 OpC 19 37 21.6 +46 22 41   7.47 6.8     ~ 360 0
8 NGC 6819 OpC 19 41 18.5 +40 11 24   8.21 7.3     ~ 608 0

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2023.11.28-17:58:25

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