Periodic flares in the methanol maser source G9.62+0.20E

Goedhart, S.; Gaylard, M. J.; Walt, D. J. van der

doi:10.1046/j.1365-8711.2003.06426.x

Cited by 83 publications

(84 citation statements)

References 22 publications

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“…Various mechanisms can produce a change in magnetic field. It has been suggested that the periodic maser flares are caused by changes in the maser pumping resulting from a binary interaction between a massive protostar and companion (Goedhart et al 2003). Interactions between the magnetospheres of the two companions could cause a periodic behavior of the magnetic field, as has been observed in young low-mass binary systems (e.g., Massi et al 2008).…”

Section: Possible Origin Of the Observed Variabilitymentioning

confidence: 93%

Possible magnetic field variability during the 6.7 GHz methanol maser flares of G09.62+0.20

Vlemmings

Goedhart

Gaylard

2009

A&A

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Context. Polarization of maser emission contains unique information on the magnetic field in the densest regions of massive star formation. Aims. Magnetic field induced Zeeman-splitting has been measured for the strongest known 6.7 GHz methanol maser, which arises in the massive star-forming region G09.62+0.20. This maser is one of a handful of periodically flaring methanol masers. Magnetic field measurements can possibly provide insights into the elusive mechanism responsible for this periodicity. Methods. The 100-m Effelsberg telescope was used to monitor the 6.7 GHz methanol masers of G09.62+0.20, in weekly intervals, for just over a two-month period during which one of the maser flares occurred. Results. With the exception of a two-week period during the peak of the maser flare, we measure a constant magnetic field of B || ≈ 11 ± 2 mG in the two strongest maser components of G09.62+0.20 that are separated by more than 200 AU. In the two-week period coinciding exactly with the peak of the maser flare of the strongest maser feature, we measure a sharp decrease and possible reversal of the Zeeman-splitting. Conclusions. While the two phenomena are clearly related, the Zeeman-splitting decrease occurs only close to the flare maximum. Intrinsic magnetic field variability is thus unlikely to be the reason for the maser variability. The exact cause of both variabilities is still unclear, but it could be related to either background amplification of polarized emission or the presence of a massive protostar with a close-by companion. However, the variability in the splitting between the right-and left-circular polarizations could also be caused by non-Zeeman effects related to the radiative transfer of polarized maser emission. In this case we can place limits on the magnetic field orientation and the maser saturation level.

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Section: Possible Origin Of the Observed Variabilitymentioning

confidence: 93%

Possible magnetic field variability during the 6.7 GHz methanol maser flares of G09.62+0.20

Vlemmings

Goedhart

Gaylard

2009

A&A

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“…To date, periodic variations in the maser emission have been detected from a dozen HMYSOs (Goedhart, Gaylard & van der Walt 2003, 2004Goedhart et al 2009Goedhart et al , 2014Araya et al 2010;Fujisawa et al 2014). They are characterized either by flaring or sinusoidal patterns with periods ranging from 29.5 to 668 d and the relative amplitude from 0.2 to more than 30 (Fujisawa et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Discovery of four periodic methanol masers and updated light curve for a further one

Szymczak

Wolak

Bartkiewicz

2015

Monthly Notices of the Royal Astronomical Society

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We report the discovery of 6.7 GHz methanol maser periodic flares in four massive star forming regions and the updated light curve for the known periodic source G22.357+0.066. The observations were carried out with the Torun 32 m radio telescope between June 2009 and April 2014. Flux density variations with period of 120 to 245 d were detected for some or all spectral features. A variability pattern with a fast rise and relatively slow fall on time-scale of 30−60 d dominated. A reverse pattern was observed for some features of G22.357+0.066, while sinusoidal-like variations were detected in G25.411+0.105. A weak burst lasting ∼520 d with the velocity drift of 0.24 km s −1 yr −1 occurred in G22.357+0.066. For three sources for which high resolution maps are available, we found that the features with periodic behaviour are separated by more than 500 au from those without any periodicity. This suggests that the maser flares are not triggered by large-scale homogeneous variations in either the background seed photon flux or the luminosity of the exciting source and a mechanism which is able to produce local changes in the pumping conditions is required.

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“…6.7 GHz methanol masers show a characteristic "periodic" flux variation, discovered by Goedhart et al (2003). The periodic variations have been detected in thirteen methanol maser sources so far, for which the observed period ranges between 30 and 668 days (Goedhart et al (2004(Goedhart et al ( ), 2009Araya et al (2010); Szymczak et al (2011);Fujisawa et al (2014); Maswanganye et al (2014)).…”

Section: Introductionmentioning

confidence: 93%

FLUX MONITORING OF 6.7 GHz METHANOL MASER TO SYSTEMATICALLY RESEARCH PERIODIC VARIATIONS USING THE HITACHI 32-m

Sugiyama¹,

Yonekura²,

Motogi³

et al. 2015

Publications of The Korean Astronomical Society

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We have initiated single-dish monitoring observations of ∼400 methanol maser sources at 6.7 GHz using the Hitachi 32-m radio telescope from December 2012 to systematically research periodic flux variations, which are observed in some methanol maser sources associated with high-mass (proto-)stars. In our monitoring, we have made daily monitoring, so that each source has been observed every nine days with an integration time of 5 min (typical 3 σ detection sensitivities of 0.9 Jy). The monitoring observations help us statistically understand periodic flux variations with a period longer than 50 days. As an initial result, we present a new detection of periodic flux variations in the 6.7 GHz methanol maser source G 036.70+00.09. The period of the flux variations is ∼53 days (∼0.019 cycles day −1 ), and seems to be stable over 9 cycles, at least until the middle of August 2014.

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Periodic flares in the methanol maser source G9.62+0.20E

Cited by 83 publications

References 22 publications

Possible magnetic field variability during the 6.7 GHz methanol maser flares of G09.62+0.20

Possible magnetic field variability during the 6.7 GHz methanol maser flares of G09.62+0.20

Discovery of four periodic methanol masers and updated light curve for a further one

FLUX MONITORING OF 6.7 GHz METHANOL MASER TO SYSTEMATICALLY RESEARCH PERIODIC VARIATIONS USING THE HITACHI 32-m

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