J/MNRAS/475/5144 Magnetic early B-type stars. I. (Shultz+, 2018)
The magnetic early B-type stars. I: magnetometry and rotation.
Shultz M., Wade G.A., Rivinius Th., Neiner C., Alecian E., Bohlender D.,
Monin D., Sikora J., MiMeS collaboration, BinaMIcS collaboration
<Mon. Not. R. Astron. Soc. 475, 5144 (2018)>
=2018MNRAS.475.5144S 2018MNRAS.475.5144S (SIMBAD/NED BibCode)
ADC_Keywords: Magnetic fields ; Stars, early-type ; Stars, Bp ; Stars, B-type ;
Rotational velocities
Keywords: magnetic fields - stars: chemically peculiar - stars: early-type -
stars: magnetic field - stars: massive - stars: rotation
Abstract:
The rotational and magnetic properties of many magnetic hot stars are
poorly characterized, therefore the MiMeS and BinaMIcS collaborations
have collected extensive high-dispersion spectropolarimetric datasets
of these targets. We present longitudinal magnetic field measurements
<BZ> for 52 early B-type stars (B5 to B0), with which we attempt to
determine their rotational periods Prot. Supplemented with
high-resolution spectroscopy, low-resolution DAO circular
spectropolarimetry, and archival Hipparcos photometry, we determined
Prot for 10 stars, leaving only 5 stars for which Prot could not be
determined. Rotational ephemerides for 14 stars were refined via
comparison of new to historical magnetic measurements. The
distribution of Prot is very similar to that observed for the cooler
Ap/Bp stars. We also measured vsini and vmac for all stars.
Comparison to non-magnetic stars shows that vsini is much lower for
magnetic stars, an expected consequence of magnetic braking. We also
find evidence that vmac is lower for magnetic stars. LSD profiles
extracted using single-element masks revealed widespread, systematic
discrepancies in <BZ> between different elements: this effect is
apparent only for chemically peculiar stars, suggesting it is a
consequence of chemical spots. Sinusoidal fits to H line <BZ>
measurements (which should be minimally affected by chemical spots),
yielded evidence of surface magnetic fields more complex than simple
dipoles in 6 stars for which this has not previously been reported;
however, in all 6 cases the second- and third-order amplitudes are
small relative to the first-order (dipolar) amplitudes.
Description:
Longitudinal magnetic field measurements of early B-type stars derived
from 1) least-squares deconvolution profiles extracted from
high-resolution spectropolarimetric data (ESPaDOnS, Narval, HARPSpol),
using masks consisting of metallic lines, metallic + He lines,
individual chemical elements, as well as single-line H measurements;
and 2) from single-line low-resolution spectropolarimetric
observations with dimaPol.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 94 52 Summary of the sample stars and available
spectropolarimetric, spectroscopic, and
photometric observations
bz_hr.dat 77 9540 High-resolution longitudinal magnetic field
measurements from ESPaDOnS, Narval, and HARPSpol
for 49 stars
dao_bz.dat 43 108 Low-resolution longitudinal magnetic field
measurements from dimaPol for 10 stars
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Star HD name (HDNNNNNNA) or ALS3694
12- 24 A13 --- OName Other name
26- 39 A14 --- SpType Spectral type
41- 58 A18 --- Rem Remarks (1)
60- 61 I2 --- E ?=- Number of high-dispersion spectropolarimetric
observations obtained with ESPaDOnS
63- 64 I2 --- N ?=- Number of high-dispersion spectropolarimetric
observations obtained with Narval
66- 68 I3 --- H ?=- Number of high-dispersion spectropolarimetric
observations obtained with HARPSpol
70- 72 I3 --- T ?=- Total number of magnetic measurements
74- 77 I4 --- <S/N> ?=- Mean signal-to-noise ratio (2)
79- 80 I2 --- D ?=- Number of DAO observations obtained with the
low-dispersion dimaPol spectropolarimeter
82- 83 I2 --- F ?=- Nnumber of spectroscopic observations
obtained with FEROS
85- 87 I3 --- Hip ?=- Number of archival Hipparcos photometric
measurements
89- 90 A2 --- BZ [BZ ] Indicates stars with data in bz_hr.dat file
92- 94 A3 --- DAO [DAO ] Indicates stars with data in dao_bz.dat
file
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Note (1): Remarks indicate the type of chemical peculiarity (He-strong or
He-weak), the star's binary status (SB1/2/3), and/or pulsational variability
(beta Cep or SPB).
Note (2): low-S/N observations have been removed and spectral binning has been
performed.
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Byte-by-byte Description of file: bz_hr.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 -- Star HD name (HDNNNNNNA), except for ALS3694
12- 22 A11 -- Inst Instrument
24- 30 A7 -- Mask Line mask
33- 46 F14.6 d HJD Heliocentric Julian Date
48- 53 I6 gauss Bz Longitudinal magnetic field
56- 61 I6 gauss e_Bz Longitudinal magnetic field uncertainty
64- 69 I6 gauss Nz Null magnetic field
72- 77 I6 gauss e_Nz Null magnetic field uncertainty
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Byte-by-byte Description of file: dao_bz.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 -- Star HD name (HDNNNNNN)
10- 17 A8 -- Line Line from which the instrument was derived
19- 29 F11.5 d HJD Heliocentric Julian Date (HJD-2400000)
32- 36 I5 gauss Bz Longitudinal magnetic field
39- 43 I5 gauss e_Bz Longitudinal magnetic field uncertainty
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Acknowledgements:
Matthew Shultz, matthew.shultz(at)physics.uu.se
(End) Matthew Shultz [Uppsala Univ.], Patricia Vannier [CDS] 14-Mar-2018