J/MNRAS/483/3127 Rotational and magnetic properties of mCP stars (Sikora+, 2019)
A volume-limited survey of mCP stars within 100 pc II: rotational and magnetic
properties.
Sikora J., Wade G.A., Power J., Neiner C.
<Mon. Not. R. Astron. Soc., 483, 3127-3145 (2019)>
=2019MNRAS.483.3127S 2019MNRAS.483.3127S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Magnetic fields
Keywords: stars: chemically peculiar - stars: early-type -
stars: magnetic field - stars: rotation
Abstract:
Various surveys focusing on the magnetic properties of
intermediate-mass main-sequence (MS) stars have been previously
carried out. One particularly puzzling outcome of these surveys is the
identification of a dichotomy between the strong (≳100G), organized
fields hosted by magnetic chemically peculiar (mCP) stars and the
ultraweak (~<1G) fields associated with a small number of non-mCP MS
stars. Despite attempts to detect intermediate strength fields (i.e.
those with strengths ≳10 and ~<100G), remarkably few examples have
been found. Whether this so-called magnetic desert, separating the
stars hosting ultraweak fields from the mCP stars truly exists has not
been definitively answered. In 2007, a volume-limited
spectropolarimetric survey of mCP stars using the MuSiCoS
spectropolarimeter was initiated to test the existence of the magnetic
desert by attempting to reduce the biases inherent in previous
surveys. Since then, we have obtained a large number of ESPaDOnS and
NARVAL Stokes V measurements allowing this survey to be completed.
Here, we present the results of our homogeneous analysis of the
rotational periods (inferred from photometric and magnetic
variabilities) and magnetic properties (dipole field strengths and
obliquity angles) of the 52 confirmed mCP stars located within a
heliocentric distance of 100pc. No mCP stars exhibiting field
strengths ~<300G are found within the sample, which is consistent with
the notion that the magnetic desert is a real property and not the
result of an observational bias. Additionally, we find evidence of
magnetic field decay, which confirms the results of previous studies.
Description:
The MuSiCoS echelle spectropolarimeter was installed on the 2m
Telescope Bernard Lyot (TBL) at the Pic du Midi Observatory in 1996
where it was operational until its decommissioning in 2006. It had a
resolving power ∼35000 and was capable of obtaining circularly
polarized (Stokes V) spectra from 3900 to 8700Å (Donati et al.
1999A&AS..134..149D 1999A&AS..134..149D). For this study, we used a total of 151 Stokes V
observations of 23 stars that were obtained from 1998 February 12 to
2006 June 8.
We note that the raw MuSiCoS spectra used in this study are
unavailable and we have relied on normalized and reduced spectra from
a private archive. All of the available spectra span a wavelength
range of 4500-6600Å rather than the full range presumably
associated with the raw spectra. Furthermore, an automatic
normalization routine built into the esprit reduction package had been
applied to the spectra.
The ESPaDOnS and NARVAL echelle spectropolarimeters are twin
instruments installed at the Canada-France-Hawaii Telescope, and TBL,
respectively. They have a resolving power ∼65000 and are optimized for
a wavelength range of approximately 3600-10000Å.
We obtained 95 Stokes V observations of 37 stars from 2015 August 02
to 2016 August 10 using ESPaDOnS. Twenty-three Stokes V observations
of three stars were obtained using NARVAL from 2016 August 20 to 2017
February 20. All of the observations obtained using ESPaDOnS and
NARVAL were reduced with the LIBRE-ESPRIT software package, which is
an updated version of the esprit reduction package that was applied to
the MuSiCoS data (Donati et al. 1997MNRAS.291..658D 1997MNRAS.291..658D).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 33 32 List of confirmed mCP stars with observations
in table 1
table1.dat 43 220 *Observations of confirmed mCP stars
table2.dat 42 47 Spectropolarimetric observations of those stars
for which no Zeeman signatures were detected
table3.dat 96 48 Parameters associated with the <Bz> curves
table4.dat 98 48 Parameters associated with the magnetic field
geometries and strengths
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Note on table1.dat: those stars for which at least one definite detection was
obtained based on the criterion proposed by Donati et al. (1997MNRAS.291..658D 1997MNRAS.291..658D)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name (HD NNNNNN)
11- 12 I2 h RAh Simbad Right Ascension (J2000.0)
14- 15 I2 min RAm Simbad Right Ascension (J2000.0)
17- 21 F5.2 s RAs Simbad Right Ascension (J2000.0)
23 A1 --- DE- Simbad Declination sign (J2000.0)
24- 25 I2 deg DEd Simbad Declination (J2000.0)
27- 28 I2 arcmin DEm Simbad Declination (J2000.0)
30- 33 F4.1 arcsec DEs Simbad Declination (J2000.0)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name (HD NNNNNN)
11- 13 A3 --- Inst Instrument used to obtain observation (G1)
15- 22 F8.3 d HJD Heliocentric Julian Date
24- 28 F5.3 --- Phase ? Rotational phase
30- 36 F7.1 gauss Bz Disc-averaged longitudinal magnetic field
38- 43 F6.2 gauss e_Bz Error on Bz
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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- 9 A9 --- Name Star name (HD NNNNNN)
11- 13 A3 --- Inst Instrument used to obtain observation (G1)
15- 22 F8.3 d HJD Heliocentric Julian Date; HJD-245000
24- 27 I4 s texp Exposure time
29 I1 --- Number Number of consecutive observations
31- 36 F6.1 gauss Bz Disc-averaged longitudinal magnetic field
38- 42 F5.1 gauss e_Bz Error on Bz
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name (HD NNNNNN)
11- 24 F14.8 d Prot Adopted or derived rotational period
26- 28 I3 --- q_Prot ? Quality flag on Prot
30- 32 A3 --- r_Prot Reference of Prot (1)
34- 47 F14.8 d HJD0 Heliocentric Julian Date; HJD-240000
49- 54 F6.1 gauss B0 Mean value associated with the first-order
sinusoidal fits (2)
56- 61 F6.1 gauss e_B0 Error on B0
63- 68 F6.1 gauss B1 Amplitude associated with the first-order
sinusoidal fits (2)
70- 75 F6.1 gauss e_B1 Error on B1
77- 82 F6.3 --- r Ratio of the minimum to maximum effective
fields (equation 2 of Preston
1967ApJ...150..547P 1967ApJ...150..547P)
84- 88 F5.3 --- e_r Error on r
90 A1 --- l_Chi2 Upper limit on Chi2
92- 96 F5.1 --- Chi2 Reduced chi-squared
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Note (1): References as follows:
a = Maitzen, Weiss & Wood (1980A&A....81..323M 1980A&A....81..323M)
b = Borra & Landstreet (1980ApJS...42..421B 1980ApJS...42..421B)
c = Musielok et al. (1980AN....301...71M 1980AN....301...71M)
d = Jasinski, Muciek & Woszczyk (1981AcA....31..321J 1981AcA....31..321J)
e = Kurtz (1982MNRAS.200..807K 1982MNRAS.200..807K)
f = North & Adelman (1995A&AS..111...41N 1995A&AS..111...41N, Cat. J/A+AS/111/41)
g = Heck, Mathys & Manfroid (1987A&AS...70...33H 1987A&AS...70...33H)
h = Catalano & Leone (1994A&AS..108..595C 1994A&AS..108..595C, Cat. J/A+AS/108/595)
i = Manfroid & Renson (1994A&A...281...73M 1994A&A...281...73M)
j = Hill et al. (1998MNRAS.297..236H 1998MNRAS.297..236H)
k = Kurtz et al. (1997MNRAS.287...69K 1997MNRAS.287...69K)
l = Alecian et al. (2014A&A...567A..28A 2014A&A...567A..28A, Cat. J/A+A/567/A28)
m = Deutsch (1947ApJ...105..503D 1947ApJ...105..503D)
n = Bohlender & Landstreet (1990ApJ...358L..25B 1990ApJ...358L..25B)
o = Ziznovsky & Mikulasek (1995IBVS.4259....1Z 1995IBVS.4259....1Z)
p = Wade et al. (1998A&A...335..973W 1998A&A...335..973W, Cat. J/A+A/335/973)
q = Pyper et al. (1998A&A...339..822P 1998A&A...339..822P)
r = Sokolov (2000A&A...353..707S 2000A&A...353..707S)
s = Kurtz et al. (1994MNRAS.270..674K 1994MNRAS.270..674K)
t = Bagnulo, Landolfi & Degl'Innocenti (1999A&A...346..158B 1999A&A...346..158B)
u = Schoneich, Zelvanova & Musielok (1988mast.conf..193S)
v = Musielok (1986AcA....36..131M 1986AcA....36..131M)
w = Mathys (1991A&AS...89..121M 1991A&AS...89..121M)
x = Bychkov, Bychkova & Madej (2016MNRAS.455.2567B 2016MNRAS.455.2567B)
y = North, Brown & Landstreet (1992A&A...258..389N 1992A&A...258..389N)
Note (2): The periodogram calculation was followed by the application of a
commonly used period search analysis described, for example, by
Alecian et al. (2014A&A...567A..28A 2014A&A...567A..28A, Cat. J/A+A/567/A28). The method
involves fitting the time-series data to a function consisting of the
first two or three terms in a Fourier series using a range of fixed
periods (P); plausible rotational periods are identified as those
which yield the lowest Χ2 values. We adopted a second-order
sinusoidal fitting function given by:
f(t)=C0+C1sin(2π[t-t0]/P+Φ1)
where t0 is the epoch (set to zero during the period search analysis)
and C0, C1 and Φ1 are free parameters.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name (HD NNNNNN)
11- 12 I2 deg i ? Inclination angle
14- 15 I2 deg E_i ? Upper error on i
17- 18 I2 deg e_i ? Lower error on i
20- 23 F4.1 deg beta ? Obliquity angle
25- 28 F4.1 deg E_beta ? Upper error on beta
30- 33 F4.1 deg e_beta ? Lower error on beta
35- 39 I5 gauss Bd ? Dipole field strength
41- 46 I6 gauss E_Bd ? Upper error on Bd
48- 51 I4 gauss e_Bd ? Lower error on Bd
53- 60 F8.3 gauss Bc Critical field strength
62- 68 F7.3 gauss E_Bc Upper error on Bc
70- 76 F7.3 gauss e_Bc Lower error on Bc
78- 84 F7.1 --- Bd/Bc ? Bd to Bc ratio
86- 91 F6.1 --- E_Bd/Bc ? Upper error on Bd/Bc
93- 98 F6.1 --- e_Bd/Bc ? Lower error on Bd/Bc
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General Notes:
Note (G1): Instrument as follows:
ESP = ESPaDOnS
MUS = MuSiCoS
NAR = NARVAL
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History:
From electronic version of the journal
References:
Sikora et al., Paper I, 2019MNRAS.483.2300S 2019MNRAS.483.2300S
(End) Ana Fiallos [CDS] 26-Jul-2022