Magnetic field regulated infall on the disc around the massive protostar Cepheus A HW2

Vlemmings, Wouter; Surcis, G.; Torstensson, K.; Langevelde, H. J. van

doi:10.1111/j.1365-2966.2010.16297.x

Cited by 81 publications

(167 citation statements)

References 46 publications

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“…The angle θ is likely to be similar for both transitions. Although not much is known about the decay rate of the masers (Vlemmings et al 2010), in our case, R is also similar for both maser transitions. The stimulated emission rate R is Note.…”

Section: Comparison Of Polarization Properties At 44 and 95 Ghzmentioning

confidence: 73%

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Linear Polarization of Class I Methanol Masers in Massive Star-Forming Regions

Kang

Byun

Kim

et al. 2016

ApJS

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Class I methanol masers are found to be good tracers of the interaction between outflows from massive young stellar objects with their surrounding media. Although polarization observations of Class II methanol masers have been able to provide information about magnetic fields close to the central (proto)stars, polarization observations of Class I methanol masers are rare, especially at 44 and 95 GHz. We present the results of linear polarization observations of 39 Class I methanol maser sources at 44 and 95 GHz. These two lines are observed simultaneously with one of the 21 m Korean VLBI Network telescopes in single-dish mode. Approximately 60% of the observed sources have fractional polarizations of a few percent in at least one transition. This is the first reported detection of linear polarization of the 44 GHz methanol maser. The two maser transitions show similar polarization properties, indicating that they trace similar magnetic environments, although the fraction of the linear polarization is slightly higher at 95 GHz. We discuss the association between the directions of polarization angles and outflows. We also discuss some targets having different polarization properties at both lines, including DR21(OH) and G82.58+0.20, which show the 90°polarization angle flip at 44 GHz.

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Section: Comparison Of Polarization Properties At 44 and 95 Ghzmentioning

confidence: 73%

“…For a long time, masers were thought to trace the isolated pockets of a compressed field rather than the field of an ambient medium. However, some recent studies of 1.6 GHz hydroxyl and 6.7 GHz methanol masers showed that they possibly probe the large-scale magnetic field (e.g., Fish & Reid 2006;Vlemmings et al 2010;Surcis et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Linear Polarization of Class I Methanol Masers in Massive Star-Forming Regions

Kang

Byun

Kim

et al. 2016

ApJS

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“…We made use of the adapted full radiative transfer method (FRTM) code for 6.7-GHz CH 3 OH masers (Vlemmings et al 2010;Surcis et al 2011b; to model the total intensity and the linearly polarized spectrum of every maser feature for which we were able to detect linearly polarized emission.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, the 6.7-GHz CH 3 OH masers, which are among the most abundant maser species in massive star-forming regions, are playing a crucial role in determining the magnetic field morphology (e.g., Surcis et al 2009Surcis et al , 2011bSurcis et al , 2012. Magnetic fields have mainly been detected along outflows and in a few cases on surfaces of disk/tori (Vlemmings et al 2010;Surcis et al 2009Surcis et al , 2011bSurcis et al , 2012. Moreover, 6.7-GHz CH 3 OH masers are also ideal for measuring the Zeeman-splitting even though the exact proportionality between the measured splitting and the magnetic field strength is still uncertain (Vlemmings et al 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Over the last years, the high importance of using masers as probes of magnetic fields on the smallest scales (10-100 AU) has been proven (e.g., Vlemmings et al 2006Vlemmings et al , 2010Surcis et al 2011aSurcis et al , 2011bSurcis et al , 2012. In particular, the 6.7-GHz CH 3 OH masers, which are among the most abundant maser species in massive star-forming regions, are playing a crucial role in determining the magnetic field morphology (e.g., Surcis et al 2009Surcis et al , 2011bSurcis et al , 2012.…”

Section: Introductionmentioning

confidence: 99%

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EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

Surcis

Vlemmings

Langevelde

et al. 2013

A&A

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Context. Magnetic fields have only recently been included in theoretical simulations of high-mass star formation. The simulations show that magnetic fields play an important role in the formation and dynamics of molecular outflows. Masers, in particular 6.7-GHz CH 3 OH masers, are the best probes of the magnetic field morphologies around massive young stellar objects on the smallest scales of 10-100 AU. Aims. Providing new observational measurements of the morphology of magnetic fields around massive young stellar objects by using 6.7-GHz CH 3 OH maser emission is very important for setting constraints on the numerical simulations of massive star formation. Methods. This paper focuses on 4 massive young stellar objects, IRAS 06058+2138-NIRS 1, IRAS 22272+6358A, S255-IR, and S231, which complement our previous 2012 sample (the first EVN group). From all these sources, molecular outflows have been detected in the past. Seven of the European VLBI Network antennas were used to measure the linear polarization and Zeeman-splitting of the 6.7-GHz CH 3 OH masers in the star-forming regions in this second EVN group. Results. We detected a total of 128 CH 3 OH masing cloudlets. Fractional linear polarization (0.8%-11.3%) was detected towards 18% of the CH 3 OH masers in our sample. The linear polarization vectors are well ordered in all the massive young stellar objects. We measured significant Zeeman-splitting in IRAS 06058+2138-NIRS 1 (ΔV Z = 3.8 ± 0.6 m s −1 ) and S255-IR (ΔV Z = 3.2 ± 0.7 m s −1 ). Conclusions. By considering the 20 massive young stellar objects towards which the morphology of magnetic fields was determined by observing 6.7-GHz CH 3 OH masers in both hemispheres, we find no evident correlation between the linear distributions of CH 3 OH masers and the outflows or the linear polarization vectors. On the other hand, we present first statistical evidence that the magnetic field (on scales 10-100 AU) is primarily oriented along the large-scale outflow direction. Moreover, we empirically find that the linear polarization fraction of unsaturated CH 3 OH masers is P l < 4.5%.

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Magnetic Fields with the Atacama Large Millimeter/Submillimeter Array

Vlemmings

2014

Astrophysics and Space Science Library

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The Atacama Large Millimeter/submillimeter Array (ALMA) is one of the largest radio telescopes and is located at 5;000 m altitude in the Atacama desert in Chile. Its unprecedented sensitivity at extremely high angular and spectral resolution in the (sub-)millimetre wavelength regime, allows for countless advances in astrophysics. One of the areas in which ALMA can make unique contributions, is in that of the study of astrophysical magnetic fields. ALMA is expected to map the magnetic field geometry, and in some cases strength, in a large number of star forming regions, around evolved stars and planetary nebulae, and in nearby galaxies. This chapter provides examples of the amount of improvement ALMA offers the study of magnetic fields based on the current state-of-the-art and shortly introduces new tools that will be available to analyse (sub-)millimetre polarimetric observations. The Atacama Large Millimeter/Submillimeter ArrayThe Atacama Large Millimeter/submillimeter Array (ALMA) is a large international (sub-)millimeter-wavelength radio telescope array in the Atacama Desert of northern Chile. It consists of a total of 66 antennas operating in the wavelength range from 0:4 to 4 mm. Because of its unmatched sensitivity at very high spectral and spatial resolution, ALMA provides new insights into many astrophysical topics, from the formation of stars and planets to the evolution of the most distant galaxies. As ALMA is able to observe in full polarization mode, it can also reveal the magnetic field with a sensitivity and resolution that has not previously been possible.ALMA is a partnership between Europe, North America (USA and Canada) and East Asia (Japan and Taiwan) in cooperation with the Republic of Chile. The ALMA project is coordinated by the Joint ALMA Office based in Santiago de Chile. The ALMA observatory is operated from the Operation Support Facility (OSF), which is situated at 2,900 m altitude. The array itself and the correlator are located at the W. Vlemmings ( )

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Magnetic field regulated infall on the disc around the massive protostar Cepheus A HW2

Cited by 81 publications

References 46 publications

Linear Polarization of Class I Methanol Masers in Massive Star-Forming Regions

Linear Polarization of Class I Methanol Masers in Massive Star-Forming Regions

EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions

Magnetic Fields with the Atacama Large Millimeter/Submillimeter Array

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