J/MNRAS/465/2432 MiMeS magnetic analysis of O-type stars (Grunhut+, 2017)
The MiMeS survey of Magnetism in Massive Stars:
magnetic analysis of the O-type stars.
Grunhut J.H., Wade G.A., Neiner C., Oksala M.E., Petit V., Alecian E.,
Bohlender D.A., Bouret J.-C., Henrichs H.F., Hussain G.A.J., Kochukhov O.
<Mon. Not. R. Astron. Soc., 465, 2432-2470 (2017)>
=2017MNRAS.465.2432G 2017MNRAS.465.2432G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Stars, O ; Magnetic fields
Keywords: instrumentation: polarimeters - surveys - stars: early-type -
stars: magnetic field - stars: massive - stars: rotation
Abstract:
We present the analysis performed on spectropolarimetric data of 97
O-type targets included in the framework of the Magnetism in Massive
Stars (MiMeS) Survey. Mean least-squares deconvolved Stokes I and V
line profiles were extracted for each observation, from which we
measured the radial velocity, rotational and non-rotational broadening
velocities, and longitudinal magnetic field Bl. The investigation of
the Stokes I profiles led to the discovery of two new multiline
spectroscopic systems (HD 46106, HD 204827) and confirmed the presence
of a suspected companion in HD 37041. We present a modified strategy
of the least-squares deconvolution technique aimed at optimizing the
detection of magnetic signatures while minimizing the detection of
spurious signatures in Stokes V. Using this analysis, we confirm the
detection of a magnetic field in six targets previously reported as
magnetic by the MiMeS collaboration (HD 108, HD 47129A2, HD 57682,
HD 148937, CPD-28 2561, and NGC 1624-2), as well as report the
presence of signal in Stokes V in three new magnetic candidates
(HD 36486, HD 162978, and HD 199579). Overall, we find a magnetic
incidence rate of 7±3 per cent, for 108 individual O stars
(including all O-type components part of multiline systems), with a
median uncertainty of the Bl measurements of about 50G. An
inspection of the data reveals no obvious biases affecting the
incidence rate or the preference for detecting magnetic signatures in
the magnetic stars. Similar to A- and B-type stars, we find no link
between the stars' physical properties (e.g. Teff, mass, and age)
and the presence of a magnetic field. However, the Of?p stars
represent a distinct class of magnetic O-type stars.
Description:
As described by Paper I (Wade et al., 2016, Cat. J/MNRAS/456/2),
high-resolution circular polarization (Stokes V) spectra of 110
Wolf-Rayet (WR) and O-type targets were collected in the context of
the MiMeS project. Of these targets, three magnetic stars
(theta1 Ori C, Donati et al., 2002MNRAS.333...55D 2002MNRAS.333...55D; zeta Ori A,
Bouret et al., 2008MNRAS.389...75B 2008MNRAS.389...75B; and HD 191612, Donati et al.,
2006MNRAS.365L...6D 2006MNRAS.365L...6D) were previously known or highly suspected to host
a magnetic field and were observed as part of the targeted component
(TC). The 11 WR stars were previously discussed by de la Chevrotiere
et al. (2013ApJ...764..171D 2013ApJ...764..171D) and de la Chevrotiere et al.
(2014ApJ...781...73D 2014ApJ...781...73D) and are not further discussed here with the
exception of HD 190918, which also contains a spectroscopic O-star
companion that is included in this study. In this paper, we focus on
the 97 survey component (SC) systems that host an O-type star.
A total of 879 Stokes V observations of these 97 targets were obtained
with the Echelle SpectroPolarimetric Device for the Observations of
Stars (ESPaDOnS), Narval, and HARPSpol echelle spectropolarimeters.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
stars.dat 49 97 List of studied stars
tablec1.dat 140 350 Table of observations and magnetic results
for spectroscopically single stars
tablec2.dat 159 146 Table of observations and magnetic results for
spectroscopic binary systems
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See also:
J/MNRAS/456/2 : MiMeS survey of magnetism in massive stars (Wade+, 2016)
Byte-by-byte Description of file: stars.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Name adopted in the analysis
15- 16 I2 h RAh Simbad right ascension (J2000)
18- 19 I2 min RAm Simbad right ascension (J2000)
21- 25 F5.2 s RAs Simbad right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 37 F4.1 arcsec DEs Declination (J2000)
39- 49 A11 --- Table Name of the table with observations results
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Name adopted in the analysis
13- 24 A12 --- OName Common name
25- 40 A16 --- SpType Spectral type and the luminosity class
42- 50 A9 --- Mask Adopted line mask
52- 61 A10 "date" Obs.Date Observation date
63- 71 F9.4 d HJD Heliocentric Julian date at mid-exposure
(HJD-2450000)
73- 81 A9 s TExp Exposure time of the polarimetric sequence
83 A1 --- Inst [NEH] Instrument used (G1)
85- 88 I4 --- S/N ?=- Peak S/N in the co-added spectrum within
the range of 500-600nm
90- 93 F4.1 km/s Width ?=- Optimal velocity width determined for the
binned LSD profil
95- 96 A2 --- Det [DD MD ND -] Detection flag (G2)
98-101 I4 km/s Intlim1 ?=- Integration range corresponding to the
line profile
102 A1 --- --- [,]
103-105 I3 km/s Intlim2 ?=- Integration range corresponding to the
line profile
107-111 I5 gauss Bl ?=- Longitudinal magnetic field strength
113-117 I5 gauss Nl ?=- Longitudinal field strength measured from
the diagnostic null profile
119-122 I4 gauss e_Bl ?=- Uncertainty of the longitudinal field
124-127 I4 km/s vr ?=- Radial velocity (G3)
129-132 I4 km/s vsini ?=- Projected rotational velocity (G3)
134-136 I3 km/s vmac ?=- Additional non-rotational velocity
considered macroturbulence (G3)
138-140 I3 km/s vtot ?=- Median total line broadening vtot,
computed by summing vsini and vmac in
quadrature (G3)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablec2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Name adopted in the analysis
13- 27 A15 --- OName Common name
29- 54 A26 --- SpType Spectral type and the luminosity class
56- 64 A9 --- Mask Adopted line mask
66- 75 A10 "date" Obs.Date Observation date
77- 85 F9.4 d HJD Heliocentric Julian date at mid-exposure
(HJD-2450000)
87- 95 A9 s TExp Exposure time of the polarimetric sequence
97 A1 --- Inst [NEH] Instrument used (G1)
99-102 I4 --- S/N ?=- Peak S/N in the co-added spectrum within
the range of 500-600nm
104-107 A4 --- Comp Spectroscopic component
110-113 F4.1 km/s Width ?=- Optimal velocity width determined for the
binned LSD profil
115-116 A2 --- Det [DD MD ND -] Detection flag (G2)
118-121 I4 km/s Intlim1 ?=- Integration range corresponding to the
line profile
122 A1 --- --- [,]
123-125 I3 km/s Intlim2 ?=- Integration range corresponding to the
line profile
127-131 I5 gauss Bl ?=- Longitudinal magnetic field strength
133-137 I5 gauss Nl ?=- Longitudinal field strength measured from
the diagnostic null profile
139-142 I4 gauss e_Bl ?=- Uncertainty of the longitudinal field
144-147 I4 km/s vr ?=- Radial velocity (G3)
149-151 I3 km/s vsini ?=- Projected rotational velocity (G3)
153-155 I3 km/s vmac ?=- Additional non-rotational velocity
considered macroturbulence (G3)
157-159 I3 km/s vtot ?=- Median total line broadening vtot,
computed by summing vsini and vmac in
quadrature (G3)
--------------------------------------------------------------------------------
Global notes:
Note (G1): Instrument code as follows:
E = ESPaDOnS
N = Narval
H = HARPSpol
Note (G2): Detection flag as follows:
DD = definite detection
MD = marginal detection
ND = non-detection (ND)
Note (G3): results from the line fitting routine.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Wade et al., Paper I 2016MNRAS.456....2W 2016MNRAS.456....2W, Cat. J/MNRAS/456/2
(End) Patricia Vannier [CDS] 19-Sep-2018