Short-period variability in the Class II methanol maser source G12.89+0.49 (IRAS 18089−1732)

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

doi:10.1111/j.1365-2966.2009.15176.x

Cited by 53 publications

(85 citation statements)

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“…The observations of 6.7 GHz maser flux in several sources have shown a significant level of variability on timescales of a few days to several years (Caswell et al 1995;MacLeod & Gaylard 1996;Goedhart et al 2004Goedhart et al , 2009Sugiyama et al 2008). The possible causes of variability are changes in the pump rate or the maser path length, such as those caused by large scale motions (Caswell et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Periodic variability of 6.7 GHz methanol masers in G22.357 + 0.066

Szymczak

Wolak

Bartkiewicz

et al. 2011

A&A

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Aims. We report the discovery of periodic flares of 6.7 GHz methanol maser in the young massive stellar object G22.357+0.066. Methods. The target was monitored in the methanol maser line over 20 months with the Torun 32 m telescope. The emission was also mapped at two epochs using the EVN. Results. The 6.7 GHz methanol maser shows periodic variations with a period of 179 days. The periodic behavior is stable for the last three densely sampled cycles and has even been stable over ∼12 years, as the archival data suggest. The maser structure mapped with the EVN remains unchanged at two epochs just at the putative flare maxima separated by two years. The time delays of up to ∼16 days seen between maser features are combined with the map of spots to construct the 3-dimensional structure of the maser region. The emission originating in a single ∼100 AU layer can be modulated by periodic changes in the infrared pumping radiation or in the free-free background emission from an HII region.

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Section: Introductionmentioning

confidence: 99%

Periodic variability of 6.7 GHz methanol masers in G22.357 + 0.066

Szymczak

Wolak

Bartkiewicz

et al. 2011

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%

“…For sources with periods of 240-400 d it has been postulated that a binary interaction between a HMYSO and its companion could periodically alter either the seed photon flux or pump rate in the maser region (van der Walt et al 2009;van der Walt 2011). Specifically, a colliding-wind binary (CWB) could produce a periodic pulse in the ionising radiation that changes the electron density and periodically modulates the free-free emission from the H ii region against which the maser clouds are projected.…”

Section: Introductionmentioning

confidence: 99%

“…The 12.2 GHz maser emission, when observed, commonly shows periodic amplitude variations higher than those at 6.7 GHz (Goedhart et al 2014). G9.62+0.20E, an archetype of the class, ⋆ E-mail: msz@astro.umk.pl exhibits a regular flaring behaviour also in the 107 GHz methanol maser line (van der Walt et al 2009). Correlated periodic variability between the 6.7 GHz methanol and 4.8 GHz formaldehyde maser lines has been reported for G37.55−0.20 (Araya et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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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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“…It is known that the 6.7 GHz methanol maser emission can be thought to often be associated with circumstellar disks around forming massive stars (e.g., Norris et al 1993;Bartkiewicz et al 2009;Sanna et al 2010). Some of the methanol masers show periodic flux variations over 10 days (e.g., Goedhart et al 2004Goedhart et al , 2009). Since the 6.7 GHz methanol masers are radiatively pumped by infrared emission of warm dusts (∼150 K; Cragg et al 2005), the periodicity could reflect the luminosity variation of nearby forming massive stars or accretion disks.…”

Section: Introductionmentioning

confidence: 99%

Direct Diagnostics of Forming Massive Stars: Stellar Pulsation and Periodic Variability of Maser Sources

Inayoshi

Sugiyama

Hosokawa

et al. 2013

ApJ

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The 6.7 GHz methanol maser emission, a tracer of forming massive stars, sometimes shows enigmatic periodic flux variations over several 10-100 days. In this Letter, we propose that these periodic variations could be explained by the pulsation of massive protostars growing under rapid mass accretion with rates ofṀ * 10 −3 M yr −1 . Our stellar evolution calculations predict that the massive protostars have very large radii exceeding 100 R at maximum, and here we study the pulsational stability of such bloated protostars by way of the linear stability analysis. We show that the protostar becomes pulsationally unstable with various periods of several 10-100 days depending on different accretion rates. With the fact that the stellar luminosity when the star is pulsationally unstable also depends on the accretion rate, we derive the period-luminosity relation log(L/ L ) = 4.62 + 0.98 log(P /100 days), which is testable with future observations. Our models further show that the radius and mass of the pulsating massive protostar should also depend on the period. It would be possible to infer such protostellar properties and the accretion rate with the observed period. Measuring the maser periods enables a direct diagnosis of the structure of accreting massive protostars, which are deeply embedded in dense gas and are inaccessible with other observations.

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Short-period variability in the Class II methanol maser source G12.89+0.49 (IRAS 18089−1732)

Cited by 53 publications

References 45 publications

Periodic variability of 6.7 GHz methanol masers in G22.357 + 0.066

Periodic variability of 6.7 GHz methanol masers in G22.357 + 0.066

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

Direct Diagnostics of Forming Massive Stars: Stellar Pulsation and Periodic Variability of Maser Sources

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