J/A+A/578/A102 6.7GHz methanol maser polarization in SFR (Surcis+, 2015)
EVN observations of 6.7 GHz methanol maser polarization in massive star-forming
regions. III. The flux-limited sample.
Surcis G., Vlemmings W.H.T., van Langevelde H.J., Hutawarakorn Kramer B.,
Bartkiewicz A., Blasi M.G.
<Astron. Astrophys., 578, A102-102 (2015)>
=2015A&A...578A.102S 2015A&A...578A.102S (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Masers ; Polarization
Keywords: stars: formation - masers - polarization - magnetic fields
Abstract:
Theoretical simulations and observations at different angular
resolutions have shown that magnetic fields have a central role in
massive star formation. Like in low-mass star formation, the magnetic
field in massive young stellar objects can either be oriented along
the outflow axis or randomly.
Measuring the magnetic field at milliarcsecond resolution (10-100au)
around a substantial number of massive young stellar objects permits
determining with a high statistical significance whether the direction
of the magnetic field is correlated with the orientation of the
outflow axis or not.
In late 2012, we started a large VLBI campaign with the European VLBI
Network to measure the linearly and circularly polarized emission of
6.7GHz CH3OH masers around a sample of massive star-forming regions.
This paper focuses on the first seven observed sources, G24.78+0.08,
G25.65+1.05, G29.86-0.04, G35.03+0.35, G37.43+1.51, G174.20-0.08, and
G213.70-12.6. For all these sources, molecular outflows have been
detected in the past.
We detected a total of 176 CH3OH masing cloudlets toward the seven
massive star-forming regions, 19% of which show linearly polarized
emission. The CH3OH masers around the massive young stellar object
MM1 in G174.20-0.08 show neither linearly nor circularly polarized
emission. The linear polarization vectors are well ordered in all the
other massive young stellar objects. We measured significant Zeeman
splitting toward both A1 and A2 in G24.78+0.08, and toward G29.86-0.04
and G213.70-12.6.
By considering all the 19 massive young stellar objects reported in
the literature for which both the orientation of the magnetic field at
milliarcsecond resolution and the orientation of outflow axes are
known, we find evidence that the magnetic field (on scales 10-100au)
is preferentially oriented along the outflow axes.
Description:
The first seven massive SFRs were observed at 6.7GHz in full
polarization spectral mode with eight of the EVN antennas (Effelsberg,
Jodrell, Onsala, Medicina, Noto, Torun, Westerbork, and Yebes-40m)
between November 2012 and June 2013, for a total observation time of
49h. The bandwidth was 2MHz, providing a velocity range of ∼100km/s.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 116 7 Observational details
tablea1.dat 120 53 Parameters of the 6.7GHz CH3OH maser features
detected in G24.78+0.08
tablea2.dat 120 23 Parameters of the 6.7GHz CH3OH maser features
detected in G25.65+1.05
tablea3.dat 120 18 Parameters of the 6.7GHz CH3OH maser features
detected in G29.86-0.04
tablea4.dat 120 29 Parameters of the 6.7GHz CH3OH maser features
detected in G35.03+0.35
tablea5.dat 120 19 Parameters of the 6.7GHz CH3OH maser features
detected in G37.43+1.51
tablea6.dat 75 14 Parameters of the 6.7GHz CH3OH maser features
detected in G174.20-0.08
tablea7.dat 120 20 Parameters of the 6.7GHz CH3OH maser features
detected in G213.70-12.6 (Mon R2-IRS 3/Star A)
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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- 12 A12 --- Source Source name
14- 18 A5 --- Prog Program code
20- 29 A10 "date" Obs.Date Observation date
31- 40 A10 --- Calib Calibrator name
42- 44 I3 deg Pol Polarization angle
46 I1 deg e_Pol rms uncertainty on Pol
48- 51 F4.1 mas Size1 Beam size
52 A1 --- --- [x]
53- 55 F3.1 mas Size2 Beam size
57- 62 F6.2 deg PA [] Position angle
64 I1 mJy rms rms noise (mJy/beam)
66- 67 I2 mJy s-n Self-noise in the maser emission channels
(e.g., Sault, 2012, EVLA Memo 159)
69- 70 I2 h RAh Right ascension (J2000)
72- 73 I2 min RAm Right ascension (J2000)
75- 80 F6.3 s RAs Right ascension (J2000)
82 A1 --- DE- Declination sign (J2000)
83- 84 I2 deg DEd Declination (J2000)
86- 87 I2 arcmin DEm Declination (J2000)
89- 94 F6.3 arcsec DEs Declination (J2000)
96- 98 F3.1 mas e_RAs Formal error on RA of the fringe rate mapping
100-104 F5.1 mas e_DEs Formal error on DE of the fringe rate mapping
106-116 A11 --- FileName Name of the table with 6.7GHz CH3OH
maser features
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Byte-by-byte Description of file: tablea?.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Maser Maser name
8 A1 --- n_Maser [b] Note (2)
9- 10 A2 --- Group Group to which it belong
12- 20 F9.3 mas oRA Offset in RA (1)
22- 29 F8.3 mas oDE Offset in DE (1)
31- 36 F6.3 Jy Speak Peak flux density (Jy/beam) (3)
38- 42 F5.3 Jy e_Speak rms uncertainty on Speak
44- 49 F6.2 km/s Vlsr LSR velocity (3)
51- 54 F4.2 km/s FWHM FWHM of the total intensity spectrum
(δvL) (3)
56- 60 F5.2 % Pl ? Mean linear polarization fraction
62- 65 F4.2 % e_Pl ? rms uncertainty on Pl
67- 69 I3 deg chi ? Mean linear polarization angle
71- 72 I2 deg e_chi ? rms uncertainty on chi
74 A1 --- l_dVi Limit flag on dVi
75- 77 F3.1 km/s dVi ? Intrinsic thermal linewidth (δVi)
79- 81 F3.1 km/s E_dVi ? Error on dVi (upper value)
83- 85 F3.1 km/s e_dVi ? Error on dVi (lower value)
87- 90 F4.1 [K.sr] logTbe ? Emerging brightness temperature
(logTbΔΩ)
92- 94 F3.1 [K.sr] E_logTbe ? Error on logTbe (upper value)
96- 98 F3.1 [K.sr] e_logTbe ? Error on logTbe (lower value)
100-102 F3.1 % PV ? Circular polarization fraction
104-107 F4.1 m/s dVZ ? Zeeman splitting (δVZ)
109-111 F3.1 m/s e_dVZ ? rms uncertainty on dVZ
113-114 I2 deg theta ? Maser propagation direction
116-117 I2 deg E_theta ? Error on theta (upper value)
119-120 I2 deg e_theta ? Error on theta (lower value)
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Note (1): References positions:
tablea1 : The reference position is RA=18:36:12.563 and DE=-07:12:10.787
tablea2 : The reference position is RA=18:34:20.900 and DE=-05:59:42.098
tablea3 : The reference position is RA=18:45:59.572 and DE=-02:45:01.573
tables4 : The reference position is RA=18:54:00.660 and DE=+02:01:18.551
tablea5 : The reference position is RA=18:54:14.229 and DE=+04:41:41.138
tablea6 : The reference position is RA=05:30:48.020 and DE=+33:47:54.611
tablea7 : The reference position is RA=06:07:47.860 and DE=-06:22:56.626
Note (2): b: Because of the degree of saturation,
Tbe is underestimated, dVi and theta are overestimated.
Note (3): obtained using a Gaussian fit.
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History:
From electronic version of the journal
References:
Surcis et al., Paper I 2012A&A...541A..47S 2012A&A...541A..47S
Surcis et al., Paper II 2013A&A...556A..73S 2013A&A...556A..73S
(End) Patricia Vannier [CDS] 25-Sep-2015