J/A+A/659/A3 magnetically active stars FIP bias sample (Seli+, 2022)
Extending the FIP bias sample to magnetically active stars:
Challenging the FIP bias paradigm?
Seli B., Olah K., Kriskovics L., Kovari Zs., Vida K., Balazs L.G.,
Laming J.M., van Driel-Gesztelyi L., Baker D.
<Astron. Astrophys. 659, A3 (2022)>
=2022A&A...659A...3S 2022A&A...659A...3S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Abundances ; Optical
Keywords: stars: abundances - stars: activity - stars: atmospheres
Abstract:
The different elemental abundances of the photosphere and the corona
are striking features of not only the Sun, but other stars as well.
This phenomenon is known as the FIP effect (FIP stands for first
ionization potential), and its strength can be characterized by the
FIP bias, the logarithmic abundance difference between low- and
high-FIP elements in the corona, compared to the photosphere. The FIP
bias was shown to depend on the surface temperature of the star.
We aim to extend the Teff-FIP bias relationship to a larger stellar
sample and analyse the effect of other astrophysical parameters on the
relation (e.g., surface gravity, age, activity indicators). Methods:
We compiled FIP bias and other parameters for 59 stars for which
coronal composition is available, now including evolved stars. Using
principal component analysis and linear discriminant analysis, we
searched for correlations with other astrophysical parameters within
the sample which may influence the stellar FIP bias.
Adding stars to the Teff-FIP bias diagram unveiled new features in its
structure. In addition to the previously known relationship, there
appears to be a second branch, a parallel sequence about 0.5 dex above
it. While the Teff remains the main determinant of the FIP bias, other
parameters such as stellar activity indicators also have influence. We
find three clusters in the FIP bias determinant parameter space. One
distinct group is formed by the evolved stars. Two groups contain main
sequence stars in continuation separated roughly by the sign change of
the FIP-bias value.
The new branch of the Teff-FIP bias diagram contains stars with higher
activity level, in terms of X-ray flux and rotational velocity. The
Rossby number also seems to be important, indicating possible
dependence on the type of dynamo operating in these stars influencing
their FIP bias. The two main sequence clusters run from the earliest
spectral types of A-F with shallow convection zones through G-K-early
M stars with gradually deeper convection zones, and end up with the
fully convective M dwarf stars, depicting the change of the dynamo
type with the internal differences of the main sequence stars in
connection with the FIP-bias values.
Description:
We present the astrophysical parameters of the stars with available
FIP bias measurements, and the tables showing how the FIP-bias values
were calculated.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 101 59 Astrophysical parameters
tablea1.dat 63 56 Calculation of the literature FIP bias
tablea2.dat 63 56 Calculation of the KNN FIP bias
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of the star
13- 17 F5.2 --- FIPbiaslit Literature FIP bias (1)
19- 22 F4.2 --- e_FIPbiaslit Uncertainty of the literature FIP bias
24- 28 F5.2 --- FIPbiasKNN KNN FIP bias
30- 33 F4.2 --- e_FIPbiasKNN Uncertainty of the KNN FIP bias
35- 38 I4 K Teff Effective temperature
40- 42 I3 K e_Teff Uncertainty of the effective temperature
44- 47 F4.2 [cm/s2] logg Surface gravity in cgs units
49- 53 F5.2 --- [Fe/H] ? Metallicity
55- 58 F4.2 Gyr Age ? Age
60- 64 F5.2 Rsun Rad Stellar radius
66- 71 F6.2 d Prot ? Rotational period
73- 78 F6.2 km/s vrot ? Rotational velocity at the surface
80- 84 F5.2 --- Ro ? Rossby number
86- 90 F5.2 --- logRHK ? logRHK chromospheric flux ratio
92- 96 F5.2 [10-7W] logLx Logarithm of X-ray luminosity (erg/s)
98-101 F4.2 [mW/m2] logFx Logarithm of X-ray flux (erg/s/cm2)
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Note (1): See the paper for the individual references.
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of the star
13- 16 F4.2 --- [C/Fe]cor ? Logarithmic coronal C/Fe ratio (G1)
18- 22 F5.2 --- [N/Fe]cor ? Logarithmic coronal N/Fe ratio (G1)
24- 27 F4.2 --- [O/Fe]cor Logarithmic coronal O/Fe ratio (G1)
29- 32 F4.2 --- [Ne/Fe]cor Logarithmic coronal Ne/Fe ratio (G1)
34- 37 F4.2 --- [C/Fe]phot ? Logarithmic photospheric C/Fe ratio (G2)
39- 42 F4.2 --- [N/Fe]phot ? Logarithmic photospheric N/Fe ratio (G2)
44- 47 F4.2 --- [O/Fe]phot Logarithmic photospheric O/Fe ratio (G2)
49- 52 F4.2 --- [Ne/Fe]phot Logarithmic photospheric Ne/Fe ratio (G2)
54- 58 F5.2 --- FIPbiaslit Literature FIP bias (1)
60- 63 F4.2 --- e_FIPbiaslit Uncertainty of the literature FIP bias
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Note (1): See the paper for the references.
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of the star
13- 16 F4.2 --- [C/Fe]cor ? Logarithmic coronal C/Fe ratio (G1)
18- 22 F5.2 --- [N/Fe]cor ? Logarithmic coronal N/Fe ratio (G1)
24- 27 F4.2 --- [O/Fe]cor Logarithmic coronal O/Fe ratio (G1)
29- 32 F4.2 --- [Ne/Fe]cor Logarithmic coronal Ne/Fe ratio (G1)
34- 37 F4.2 --- [C/Fe]phot ? Logarithmic photospheric C/Fe ratio (G2)
39- 42 F4.2 --- [N/Fe]phot ? Logarithmic photospheric N/Fe ratio (G2)
44- 47 F4.2 --- [O/Fe]phot Logarithmic photospheric O/Fe ratio (G2)
49- 52 F4.2 --- [Ne/Fe]phot Logarithmic photospheric Ne/Fe ratio (G2)
54- 58 F5.2 --- FIPbiasKNN KNN FIP bias
60- 63 F4.2 --- e_FIPbiasKNN Uncertainty of the KNN FIP bias
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Global notes:
Note (G1): Coronal abundances are taken in quiescent or low activity state,
where available.
Note (G2): The photospheric abundances are relative to the solar values from
Asplund et al. (2009ARA&A..47..481A 2009ARA&A..47..481A) and
Drake & Testa (2005Natur.436..525D 2005Natur.436..525D) for Ne.
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Acknowledgements:
Balint Seli, seli.balint(at)csfk.org
(End) Patricia Vannier [CDS] 11-Jan-2022