J/A+A/686/A93 RGs Chromospheric indices from LAMOST spect. (Gehan+, 2024)
Magnetic activity of red giants: Correlation between the amplitude
of solar-like oscillations and chromospheric indicators.
Gehan C., Godoy-Rivera D., Gaulme P.
<Astron. Astrophys. 686, A93 (2024)>
=2024A&A...686A..93G 2024A&A...686A..93G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Asteroseismology ; Spectroscopy ; Optical
Keywords: stars: activity - binaries: close - stars: chromospheres -
stars: late-type - stars: low-mass - stars: oscillations
Abstract:
Previous studies have found that red giants (RGs) in close binary
systems undergoing spin-orbit resonance exhibit an enhanced level of
magnetic activity with respect to single RGs rotating at the same
rate, from measurements of photometric variability, S'ph, and the
chromospheric emission S-index, SCaII. Here, we consider a sample of
4465 RGs observed by the NASA Kepler mission, for which previous
studies have measured S'ph and SCaII, in order to measure
additional activity indicators that probe different heights in the
chromosphere: the near-ultraviolet (NUV) excess from NASA GALEX
photometric data, and chromospheric indices based on the depth of
Hα, MgI, and infrared CaII absorption lines from LAMOST
spectroscopic data. Firstly, as for CaII H&K, we observe that RGs
belonging to close binaries in a state of spin-orbit resonance display
larger chromospheric emission than the cohort of RGs, as is
illustrated by an NUV excess and shallower Hα and infrared
CaII lines. We report no excess of MgI emission. This result
reinforces previous claims that tidal locking leads to enhanced
magnetic fields, and allows us to provide criteria to classify active
RGs - single or binary - based on their rotation periods and
magnetic activity indices. Secondly, we strikingly observe that the
depths of the MgI and Hα lines are anticorrelated and
correlated, respectively, with the amplitude of solar-like
oscillations for a given surface gravity, logg, regardless of the
presence of photometric rotational modulation. Such a correlation
opens up future possibilities of estimating the value of magnetic
fields at the surface of RG stars, whether quiet or active, by
combining spectroscopic and asteroseismic measurements with
three-dimensional atmospheric models that include radiative transfer.
Description:
Chromospheric indices and associated uncertainties of the stars
analysed in the paper. Each star is identified with its KIC number
(Kepler Input Catalog, Cat. V/133).
The chromospheric indices were measured for 4575 red giant stars
analysed by Gaulme et al. (2020, Cat. J/A+A/639/A63).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
s-lines.dat 170 4574 Chromospheric indices and associated uncertainties
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/A+A/639/A63 : Active red giants asteroseismic + rotation param.
(Gaulme+, 2020)
Byte-by-byte Description of file: s-lines.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- KIC KIC number
11- 27 A17 --- 2MASS 2MASS designation
29- 33 F5.2 mag Kepmag Kepler magnitude
35- 36 I2 --- flagActOsc [0/60] Activity and oscillation flag (1)
38 I1 --- EvolStatus [0/2] Red giant evolutionary state (2)
40- 46 F7.2 d Prot ?=-999 Rotation period
48- 54 F7.2 [cm/s2] logg ?=-999 Asteroseismic logg
56- 62 F7.2 [cm/s2] e_logg ?=-999 Error on logg
64- 71 F8.3 mag NUVxs ?=-999 NUV excess
73- 80 F8.3 mag e_NUVxs ?=-999 Error on the NUV excess
82- 89 F8.3 --- SCaHK ?=-999 CaII H&K index
91- 98 F8.3 --- e_SCaHK ?=-999 Error on the CaII H&K index
100-107 F8.3 --- SMg ?=-999 MgI index
109-116 F8.3 --- e_SMg ?=-999 Error on the MgI index
118-125 F8.3 --- SFe ?=-999 FeI index
127-134 F8.3 --- e_SFe ?=-999 Error on the FeI index
136-143 F8.3 --- SHalpha ?=-999 Halpha index
145-152 F8.3 --- e_SHalpha ?=-999 Error on the Halpha index
154-161 F8.3 --- SCaIR ?=-999 CaII IR index
163-170 F8.3 --- e_SCaIR ?=-999 Error on the CaIR index
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Note (1): Activity and oscillation flag as follows:
0 = no act. & oscillations
1 = activity & no oscillations
2 = clear activity & oscillations
3 = possible act. & oscillations
4 = binary signal in power spectrum of light curve
5 = no act. & no oscillations
6 = classical pulsator
7 = heartbeat star
8 = double pulsator
14 = combination of 1 and 4
16 = combination of 1 and 6
24 = combination of 2 and 4
26 = combination of 2 and 6
54 = combination of 5 and 4
56 = combination of 5 and 6
60 = combination of 6 and 0
Note (2): Red giant evolutionary state as follows:
0 = unknown
1 = RGB
2 = RC
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Acknowledgements:
Charlotte Gehan, gehan(at)mps.mpg.de
(End) Charlotte Gehan [MPS], Patricia Vannier [CDS] 03-Apr-2024