Observations of SiO masers at 43 GHz with the Parkes radio telescope

Balister, M.; Batchelor, R.; Haynes, R. F.; Knowles, S. H.; McCulloch, MacCrae G.; Robinson, B. J.; Wellington, K. J.; Yabsley, D. E.

doi:10.1093/mnras/180.3.415

Cited by 23 publications

(10 citation statements)

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“…Second, there is long-term variability within a cycle in which SiO masers are correlated with the optical phase. The third type is rapid variability over a period of a few days, as shown in some observations (Balister et al 1977;Pijpers et al 1994). In this present study, we have considered only the long-term variability over the stellar cycle (of period 332.2 days).…”

Section: Temporal Variability Of Sio Maser In Mirasmentioning

confidence: 80%

Non-local radiative transfer of SiO masers in Miras

Yun

Park

2012

A&A

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Context. To properly understand the propagation of SiO masers within the shocked region of the circumstellar envelope of asymptotic giant branch stars, non-local radiative transfer calculations are required. Aims. The present study focuses on investigating how the non-linear velocity field affects the amplification of SiO masers in the circumstellar envelope of a Mira variable. Methods. We extend the capability of the coupled escape probability method to a spherical system and develop subroutines that are able to calculate the radiative transfer problems in an arbitrary velocity field. This method is applied to the model of a Mira variable that shows dramatic fluctuations in its physical conditions in the circumstellar envelope. We carry out the non-local calculations over the subset of whole epochs covering a complete stellar-pulsation cycle. We also include maser saturation in our calculations to properly treat the interaction of SiO maser radiation with the SiO molecules. Results. We reproduce the typical features of SiO masers in Mira variables and compare our results with previous large velocity gradient (LVG) calculations and observations. The region of SiO masers is very confined, at a distance of about one stellar radius from the photosphere, which implies that there has been a tangential amplification process. The relative strengths and positions of SiO masers of v = 1, J = 1−0, 2−1 and v = 2, J = 1−0 transitions are shown. The temporal variability of a SiO maser, which is driven by stellar pulsations, is also examined in this study, and our results show some differences from those of previous LVG calculations.

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Section: Temporal Variability Of Sio Maser In Mirasmentioning

confidence: 80%

Non-local radiative transfer of SiO masers in Miras

Yun

Park

2012

A&A

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“…Receiver A2 was used only during the fourth epoch (1995 April) and the sixth epoch (1995 December). Although very rapid variability has been observed in some SiO masers (Balister et al 1977; Pijpers, Pardo & Bujarrabal 1994), data taken for the same object and frequency have been co‐added if the observations were only a day or two apart, since there is no conclusive evidence of significant short‐term spectral change, at the 5σ level or above, in the present data. Five objects were detected at epochs separated by 48 h or less, three of which were Miras and two of which were supergiants.…”

Section: Observationsmentioning

confidence: 98%

A survey of high-frequency SiO masers in supergiants and AGB stars

Gray

Humphreys

Yates

1999

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TWe report the results of a survey of high-frequency SiO maser emission from a sample of 34 late-type supergiant and AGB stars. Four new sources were detected, including the ®rst detection of 301-GHz emission from an S-type star. Variability of the maser emission with stellar phase is discussed in detail. We ®nd that high-frequency SiO maser emission appears to be exceptionally weak or absent in Mira variables over an optical phase range of approximately 0.4 to 0.7. No signi®cant correlation is found between maser photon luminosity and spectral type for non-supergiant types. Centroid velocities of spectra appear to be redder than the stellar velocity over a phase range that is wider than the band where emission is weak on average. However, the conclusion that only the blue features appearing in spectra after an optical phase of 0.7±0.8 correspond to new masing objects should be viewed with caution.

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“…The molecular emission of L 2 Pup has been extensively monitored in the past fifty years; it showed the variability of the outflow velocity (Kerschbaum et al 1996;Kerschbaum & Olofsson 1999;Winters et al 2002Winters et al , 2003Lepine et al 1976Lepine et al , 1978Haikala 1990;Haikala et al 1994;Menten & Melnick 1991;Gomez Balboa & Lepine 1986;Caswell et al 1971;Knowles & Batchelor 1978;Balister et al 1977;Schöier et al 2004;González Delgado et al 2003). González Delgado et al (2003) reported that the interior of the circumstellar envelope of L 2 Pup is probably complex, based on their SiO observations.…”

Section: Toroidal Structure Hypothesismentioning

confidence: 99%

Dissecting the AGB star L₂Puppis: a torus in the making

Lykou

Klotz

Paladini

et al. 2015

A&A

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Aims. The circumstellar environment of L 2 Pup, an oxygen-rich semiregular variable, was observed to understand the evolution of mass loss and the shaping of ejecta in the late stages of stellar evolution. Methods. High-angular resolution observations from a single 8 m telescope were obtained using aperture masking in the near-infrared (1.64, 2.30 and 3.74 μm) on the NACO/VLT, both in imaging and polarimetric modes. Results. The aperture-masking images of L 2 Pup at 2.30 μm show a resolved structure that resembles a toroidal structure with a major axis of ∼140 milliarcseconds (mas) and an east-west orientation. Two clumps can be seen on either side of the star, ∼65 mas from the star, beyond the edge of the circumstellar envelope (estimated diameter is ∼27 mas), while a faint, hook-like structure appear toward the northeast. The patterns are visible both in the imaging and polarimetric mode, although the latter was only used to measure the total intensity (Stokes I). The overall shape of the structure is similar at the 3.74 μm pseudo-continuum (dust emission), where the clumps appear to be embedded within a dark, dusty lane. The faint, hook-like patterns are also seen at this wavelength, extending northeast and southwest with the central, dark lane being an apparent axis of symmetry. We interpret the structure as a circumstellar torus with inner radius of 4.2 au. With a rotation velocity of 10 km s −1 as suggested by the SiO maser profile, we estimate a stellar mass of 0.7 M .

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Observations of SiO masers at 43 GHz with the Parkes radio telescope

Cited by 23 publications

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Non-local radiative transfer of SiO masers in Miras

Non-local radiative transfer of SiO masers in Miras

A survey of high-frequency SiO masers in supergiants and AGB stars

Dissecting the AGB star L₂Puppis: a torus in the making

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Observations of SiO masers at 43 GHz with the Parkes radio telescope

Cited by 23 publications

References 0 publications

Non-local radiative transfer of SiO masers in Miras

Non-local radiative transfer of SiO masers in Miras

A survey of high-frequency SiO masers in supergiants and AGB stars

Dissecting the AGB star L2Puppis: a torus in the making

Contact Info

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Resources

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Dissecting the AGB star L₂Puppis: a torus in the making