J/MNRAS/514/4300 Late-type dwarfs logR'HK and magnetic fields (Brown+, 2022)
Linking chromospheric activity and magnetic field properties for
late-type dwarf stars.
Brown E.L., Jeffers S.V., Marsden S.C., Morin J., Boro Saikia S., Petit P.,
Jardine M.M., See V., Vidotto A.A., Mengel M.W., Dahlkemper M.N.,
(the Bcool Collaboration)
<Mon. Not. R. Astron. Soc., 514, 4300-4319 (2022)>
=2022MNRAS.514.4300B 2022MNRAS.514.4300B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Magnetic fields ; Radial velocities ; Optical
Keywords: stars: activity - stars: late-type - stars: magnetic field
Abstract:
Spectropolarimetric data allow for simultaneous monitoring of stellar
chromospheric logR'HK activity and the surface-averaged longitudinal
magnetic field, Bl, giving the opportunity to probe the relationship
between large-scale stellar magnetic fields and chromospheric
manifestations of magnetism. We present logR'HK and∨Bl
measurements for 954 mid-F to mid-M stars derived from
spectropolarimetric observations contained within the PolarBase
database. Our magnetically active sample complements previous stellar
activity surveys that focus on inactive planet-search targets. We find
a positive correlation between mean logR'HK and mean log |Bl|, but for
G stars the relationship may undergo a change between logR'HK~-4.4 and
-4.8. The mean logR'HK shows a similar change with respect to the
logR'HK variability amplitude for intermediately active G stars. We
also combine our results with archival chromospheric activity data and
published observations of large-scale magnetic field geometries
derived using Zeeman-Doppler Imaging. The chromospheric activity data
indicate a slight under-density of late-F to early-K stars with
-4.75≤logR'HK≤-4.5 . This is not as prominent as the original
Vaughan-Preston gap, and we do not detect similar under-populated
regions in the distributions of the mean |Bl|, or the Bl and logR'HK
variability amplitudes. Chromospheric activity, activity variability,
and toroidal field strength decrease on the main sequence as rotation
slows. For G stars, the disappearance of dominant toroidal fields
occurs at a similar chromospheric activity level as the change in the
relationships between chromospheric activity, activity variability,
and mean field strength.
Description:
We provide a catalog of new chromospheric activity and
surface-averaged large-scale magnetic field measurements for 954 main
sequence and youthful stars with spectral types from mid-F to mid-M.
This includes mean values and peak-to-peak variability amplitudes for
both the logR-HK and Bl, which were derived using time-series
spectropolarimetric observations from the PolarBase database.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables.dat 331 954 Chromospheric S-index and surface averaged
longitudinal field strengths
(tables 1 and 3 of the paper)
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See also:
http://polarbase.irap.omp.eu : PolarBase database home page
Byte-by-byte Description of file: tables.dat
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Bytes Format Units Label Explanations
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1- 31 A31 --- Name Main ID
33- 47 A15 --- SpType Spectral type
49- 67 A19 --- r_SpType Spectral type reference
69- 96 A28 --- GaiaDR2 GAIA DR2 ID
98-100 A3 --- Li [yes no] Detection of strong lithium
absorption lines
102-107 A6 --- Binary [Binary ] Is this a binary/multiple star
109-111 A3 --- Bl-blend [yes no] Does the Bl include contributions
from more than one binary component
113-123 F11.9 --- B-V B-V colour index
125-135 F11.6 K Teff Effective temperature
137-147 F11.9 [cm/s2] logg Surface gravity
149-160 F12.9 Lsun Lum Luminosity
162-169 F8.3 km/s RV Mean radial velocity
171-177 F7.3 km/s s_RV Radial velocity standard deviation
179-185 F7.3 km/s FWHM Mean LSD line profile full-width at
half-maximum
187-190 I4 --- o_Smean Number of S-index observations
192-203 F12.9 --- Smean ? Mean chromospheric S-index
205-213 F9.6 --- Smin ? Minimum chromospheric S-index
215-222 F8.5 --- Smax ? Maximum chromospheric S-index
224-235 F12.9 [-] logRhkmean ? Mean logR'HK
237-248 F12.9 --- logRhkrange ? Peak-to-peak range of logR'HK
250-252 I3 --- o_Blavg Number of Bl observations
254-266 F13.9 gauss Blavg ? Mean surface-averaged magnetic
field strength, Bl
268-279 F12.9 gauss e_Blavg ? Error in the mean Bl
281-291 F11.6 gauss Blrange ? Peak-to-peak Bl range
293-304 F12.9 gauss BlNavg ? Mean Bl measured from the Null LSD profile
306-317 F12.9 gauss e_BlNavg ? Error in the mean Bl measured from the
Null LSD profile
319-331 F13.9 gauss s_BlNavg ? Average uncertainty in BlN measurements
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Acknowledgements:
Emma Brown, emma.brown(at)usq.edu.au
(End) Patricia Vannier [CDS] 12-Nov-2022