J/A+A/641/A110 Chromospheric activity of nearby Sun-like stars (Gondoin, 2020)
Chromospheric activity of nearby Sun-like stars.
R'HK index signature of a recent burst of star formation.
Gondoin P.
<Astron. Astrophys. 641, A110 (2020)>
=2020A&A...641A.110G 2020A&A...641A.110G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Photometry, K-line ; Space velocities
Keywords: Galaxy: evolution - solar neighbourhood - stars: general
stars: activity - stars: chromosphere - stars: late-type
Abstract:
The chromospheric emission in the cores of the CaII H & K lines of
late-type dwarfs is a well known indicator of magnetic activity that
decreases with increasing stellar age. I use this indicator to
investigate the formation history of nearby G- and early K-type stars
with origins at galactocentric distances similar to that of the region
where the Sun was born. A parent sample of single main-sequence stars
with near-solar metallicity and known magnetic activity levels is
built from catalogues of stellar atmospheric parameters and
chromospheric activity indices. A kinematical approach uses Gaia
astrometric data to differentiate thin disc stars from thick disc
stars. Measured distributions of R'HK chromospheric activity indices
are compared with Monte Carlo simulations based on an empirical model
of chromospheric activity evolution. The thin disc includes a
significant fraction of Sun-like stars with intermediate activity
levels while most early K- and G-type stars from the thick disc are
inactive. The chromospheric activity distribution among nearby
Sun-like dwarfs from the thin disc can be explained by a combination
of an old (>6-7Gyr) star formation event (or events) and a more recent
(<3Gyr) burst of star formation. Such an event is not required to
account for the R'HK index distributions of nearby thick disc stars.
The distribution of magnetic activity among local G- and early K-type
stars with a near-solar metallicity bears the imprint of an important
star formation event that occurred ∼1.9 to 2.6Gyr ago in the thin disc
of the Milky Way.
Description:
Stellar properties of a parent sample of nearby Sun-like stars with
parallaxes greater than 20mas used in the study. For each star, the
name, spectral type, right ascension and declination expressed in the
ICRS, parallax, velocity components in the LSR, B-V colour index, V
magnitude, log(R'HK) chromospheric activity index, [Fe/H], median
absolute deviation of [Fe/H], and thick disc over thin disc membership
probability ratio are given.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tableb1.dat 219 691 Stellar properties
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Index [1/691] Sequential number
5- 13 A9 --- Name Star's name
15- 30 A16 --- SpType Spectral type
32- 49 E18.12 deg RAdeg Gaia DR2 right ascension (ICRS) at Ep=2015.5
51- 69 E19.12 deg DEdeg Gaia DR2 declination (ICRS) at Ep=2015.5
72- 89 E18.12 mas plx Gaia DR2 parallax
91-103 E13.6 km/s U Velocity (LSR) towards Galactic centre
105-117 E13.6 km/s V Velocity (LSR) along Galaxy rotation
119-131 E13.6 km/s W Velocity (LSR) towards North Galactic pole
134-145 E12.6 mag B-V B-V colour index
148-159 E12.6 mag VMAG Absolute V magnitude
161-173 E13.6 --- logR'HK Logarithm of R'HK chromospheric activity index
175-187 E13.6 [-] [Fe/H] Metallicity
190-201 E12.6 [-] s_[Fe/H] Median absolute deviation of [Fe/H]
203-219 E17.11 --- PR Thick disc over thin disc membership probability
--------------------------------------------------------------------------------
Acknowledgements:
Philippe Gondoin, Philippe.Gondoin(at)esa.int
(End) Philippe Gondoin [ESA-ESTEC, NL], Patricia Vannier [CDS] 01-Jul-2020