J/A+A/710/A16 Study of dipolar magnetic field for 2673 stars (Duchene+, 2026)
Stellar magnetic fields database and extrapolation method.
Duchene N., Girard J.N., Zarka P.
<Astron. Astrophys. 710, A16 (2026)>
=2026A&A...710A..16D 2026A&A...710A..16D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, equatorial ; Magnetic fields ; References ; Combined data
Keywords: magnetic fields - catalogs - stars: magnetic field
Abstract:
During the last two decades, thousands of stellar magnetic fields have
been measured using the Zeeman-Doppler imaging method. No unified
database gathers all measurements in an homogeneous way.
The magnetic field of a star is a key ingredient of its plasma
interactions with companions, either other stars or exoplanets, and of
its radio and X-ray emissions. The dipolar component of a star's
magnetic field, in particular, allows one to estimate the magnetic
(Poynting) flux carried away by the stellar wind, that sweeps across
exoplanets or their magnetospheres and is believed to drive electron
acceleration and radio emissions. Here we aim at building a database
of known stellar magnetic fields, inferring the dipolar component of
the field, and we present the methods that we have developed to
estimate a star's magnetic field when no measurement is available.
We have compiled published Zeeman-Doppler measurements of stellar
magnetic fields into a database, showing how to extract the dipolar
component from various measurements. We have included several other
stellar parameters in the database (mass, radius, rotation period,
effective temperature, age, V-band magnitude). Then we have built and
compared two extrapolation methods to infer stellar magnetic fields
from the other stellar parameters: a K-Nearest Neighbors method and a
neural network trained on the database.
We present a database of over 2600 stars with an estimate of their
dipolar magnetic field, and methods to predict such a parameter for
other stars where it is not measured, to much better than an order of
magnitude.
Description:
Estimation of equatorial dipolar magnetic field for 2673 stars
computed from various measures from the literature. Depending on the
quality (Qn), upper or lower limits are computed instead. For each
star, estimate of this field, quality, and description as given in the
source article are provided in table.dat as well as literature
references and DOI in refs.dat and dois.dat.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 333 2672 Estimation of equatorial dipolar magnetic field
of our stars sample and literature references
(table 2)
refs.dat 358 239 Literature references of the sources
dois.dat 36 339 Literature DOI of the sources
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Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 27 A27 --- Name Main ID of the star on SIMBAD (Simbad_ID)
29- 31 F3.1 --- Q Quality indicator of the literature values (Qn+)
33- 39 A7 --- Flag Flag for descriptors of value types (Tag) (1)
41- 62 F22.16 gauss B Equatorial dipolar magnetic field estimate
(Bdipeq)
64- 65 I2 --- o_B Number of values from the literature used to
obtain this estimate (N_est)
67- 72 A6 --- f_B Whether the estimate is a lower 2167 times or
upper 429 times limit or a direct estimate 76
(T_est)
74- 84 A11 --- Note Type of information available in the literature
as described y their respective source articles
(Comment) (2)
86- 312 A227 --- r_Note Bibcodes of the respective source articles, in
refs.dat file (Bibcodes)
314- 333 A20 --- n_Note DOI of the respective source articles, in
dois.dat (DOI)
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Note (1): Descriptors are as follows:
BED = Dipolar m. f. at equator, 20 occurences in our sample
BET = Equatorial m. f. and, 4 occurences in our sample
BLON = Longitudinal m. f., 2167 occurences in our sample
BMD = Mean dipolar m. f. over the disk, 47 occurences in our sample
BMT = Mean m. f., 404 occurences in our sample
BPD = Dipolar m. F at pole, 30 occurences in our sample
BUD = M. f. measured in a deeper layer, 1 occurence in our sample
BUT = M. F. at unspecified location, 1 occurence in our sample
Note (2): Comments are as follows:
1 = Average magnetic field, 290 occurences in our sample
2 = Average surface magnetic field, 2 occurences in our sample
3 = Dipole component of magnetic field, 1 occurences in our sample
4 = Mean dipolar magnetic field, 1 occurences in our sample
5 = absolute value of mean longitudinal magnetic field,
16 occurences in our sample
6 = average magnetic flux, 5 occurences in our sample
7 = average surface magnetic flux, 43 occurences in our sample
8 = averaged dipolar magnetic field, 6 occurences in our sample
9 = averaged quadratic effective magnetic field value,
1707 occurences in our sample
10 = dipolar component at magnetic pole, 1 occurences in our sample
11 = dipolar component of the average large-scale field,
1 occurences in our sample
12 = dipole field strength, 44 occurences in our sample
13 = dipole magnetic field according to APERO,
1 occurences in our sample
14 = dipole magnetic field according to Libre-Esprit,
1 occurences in our sample
15 = global magnetic field, 2 occurences in our sample
16 = longitudinal magnetic field averaged over the stellar disk,
335 occurences in our sample
17 = lower-bound mean surface dipolar field,
5 occurences in our sample
18 = magnetic field average over the visible surface,
46 occurences in our sample
19 = magnetic field of the star, 1 occurences in our sample
20 = magnetic field strength averaged over the stellar surface,
1 occurences in our sample
21 = magnetic strength at the source of bursts,
1 occurences in our sample
22 = maximum magnetic field component at lat 0deg,
4 occurences in our sample
23 = mean longitudinal magnetic fields, 770 occurences in our sample
24 = mean magnetic field in inner corona, 1 occurences in our sample
25 = mean surface magnetic field, 5 occurences in our sample
26 = polar magnetic field, 28 occurences in our sample
27 = root mean square longitudinal magnetic field strength,
1157 occurences in our sample
28 = surface averaged magnetic field, 30 occurences in our sample
29 = surface magnetic field, 59 occurences in our sample
30 = upper limit of detection in the case of a dipolar field,
20 occurences in our sample
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Ref Reference code
5- 23 A19 --- BibCode ADS/Simbad bibcode
25- 88 A64 --- DOI DOI
90-110 A21 --- Author First author's name
112-303 A192 --- Title Reference title
305-332 A28 --- n_Ref Reference publication items as journal abbrev,
volume, pages and year
334-358 A25 --- Cat Reference VizieR catalog
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Byte-by-byte Description of file: dois.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Ref Reference code
5- 36 A32 --- DOI DOI
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Acknowledgements:
From Noemie Duchene, 1quentin.duchene(at)gmail.com
The authors acknowledge funding from the ERC under the European Union's
Horizon 2020 research and innovation programme
(grant agreement no. 101020459 - Exoradio).
License: CC-BY-4.0
(End) Luc Trabelsi [CDS] 13-Apr-2026