High resolution observations of SiO masers: Comparing   the spatial 
distribution at 43 and 86 GHz

Soria-Ruiz, R.; Alcolea, J.; Colomer, F.; Desmurs, J. F.; Marvel, Kevin B.; Diamond, P. J.

doi:10.1051/0004-6361:20041139

Cited by 69 publications

(111 citation statements)

References 26 publications

(44 reference statements)

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“…The spots of both transitions are placed in similar regions, but are rarely coincident and the v = 2 J = 1−0 spot ring is slightly closer to the star. All the relevant observational data agree (at least qualitatively) with the results of radiative pumping models including line overlap, as proposed by Soria-Ruiz et al (2004). The v = 2 J = 1−0 maser is predicted by the model to be at a slightly shorter distance than v = 1 J = 1−0, by about 5−10% of the radius, the v = 1 J = 2−1 should be clearly farther (and require quite different excitation conditions), and the v = 2 J = 2−1 maser should practically be not excited.…”

Section: Comparison With Theoretical Model Predictionssupporting

confidence: 83%

“…The discussion of this topic has dramatically changed from when the first comparisons between v = 1 J = 1−0 and J = 2−1 maser distributions were performed (Soria-Ruiz et al 2004, 2005, 2007. The v = 1 J = 2−1 maser spots systematically occupy a ring with a significantly larger radius than that of v = 1 J = 1−0, and both spot distributions are completely unrelated.…”

Section: Comparison With Theoretical Model Predictionsmentioning

confidence: 99%

“…These infrared transitions have very similar frequencies and can radiatively interact. Soria-Ruiz et al (2004) use a radiative pumping scheme for SiO masers, coupled with a model for H 2 O excitation, which allowed those authors to study the effects of the overlapping line pair onto SiO masers. (Since line overlap is a radiative phenomenon, its effects are always more noticeable when the population transfer between levels mostly occur by means of radiative transitions, rather than when collisions dominate.)…”

Section: Comparison With Theoretical Model Predictionsmentioning

confidence: 99%

“…The quenching of the (otherwise intense) v = 2 J = 2−1 maser is also produced, in agreement with observations. A very important consequence is that, according to Soria-Ruiz et al (2004), the overlap introduces a strong coupling between v = 1, 2 J = 1−0 masers, which now are predicted to require very similar conditions to be intense, while the v = 1 J = 2−1 maser is less affected by this phenomenon and its masing conditions become significantly different from those for the other two lines. Nevertheless, the spatial coincidence of the v = 1, 2 J = 1−0 masers is not predicted to be exact, probably because the SiO vibrational excitation is radiative in this model, and some difference in the brightness distribution persists.…”

Section: Comparison With Theoretical Model Predictionsmentioning

confidence: 99%

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VERA observations of SiO maser emission from R Aquarii

Kamohara¹,

Bujarrabal²,

Honma³

et al. 2010

A&A

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Aims. We aim to study the spatial distribution of the v = 1 and v = 2 J = 1−0 SiO maser emission from R Aqr, a well known stellar symbiotic system. In particular, we intend to determine the annual parallax and proper motion of the source by means of measurements of the absolute coordinates of the maser spots. Methods. We performed VLBI observations of the v = 1 and v = 2 J = 1−0 maser emission, at 7 mm wavelength, using VERA. We present observations made in 11 epochs, between December 2004 and October 2006, and observations by other authors are also discussed. VERA provides very high spatial resolution and accurate astrometric measurements, thanks to its double-beam observing system. From fitting ring-like structures to the maser spot distributions, we determine absolute J2000 coordinates of the central star.(SiO maser emission is known to be distributed around the star forming spot rings at a few stellar radii.) Results. Maps with accurate absolute coordinates were obtained in 8 epochs. From the coordinates determined for the central star, we measured parallax and linear proper motion. We obtain π = 4.7 ± 0.8 mas, compatible with, but much more accurate than, the Hipparcos value (5.07 ± 3.15 mas), and deduce a distance of R Aqr D = 214 +45 −32 pc. Our accurate astrometry also yields a reliable comparison between the spot distributions of both v = 1 and v = 2 J = 1−0 lines. We find that both masers come from similar regions, i.e. at similar distances from the star and defining common spot clusters, confirming previous results. But the coincidences between spots of both lines are very rare, within the spatial and spectral resolution of our experiments. This result is found for eight epochs, spanning more than one pulsation cycle (of the cool Mira-type component). We argue that explaining the finer details of the v = 1, 2 J = 1−0 distributions found here would require new theoretical efforts. Finally, our observations also allow the study of the structure and dynamics of the close circumstellar shells in R Aqr. We do not confirm the previous suggestion that these shells are rotating; instead, we conclude that the observed kinematics is very probably caused by pulsations and random movements. The spatial distribution of the maser spots is found to be variable, but to show a stable axial symmetry.

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Section: Comparison With Theoretical Model Predictionssupporting

confidence: 83%

Section: Comparison With Theoretical Model Predictionsmentioning

confidence: 99%

Section: Comparison With Theoretical Model Predictionsmentioning

confidence: 99%

Section: Comparison With Theoretical Model Predictionsmentioning

confidence: 99%

See 2 more Smart Citations

VERA observations of SiO maser emission from R Aquarii

Kamohara¹,

Bujarrabal²,

Honma³

et al. 2010

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…The radial offset, Δr p , between the locations where the peak number densities of v = 1 and v = 2 features occur is ∼11 AU. This is substantially larger than the offsets observed in evolved stars (Δr p 1 AU; e.g., Desmurs et al 2000;Soria-Ruiz et al 2004;Yi et al 2005). Furthermore, we find no evidence for variation in the relative distributions of the v = 1 and v = 2 masers during our monitoring.…”

Section: Total Intensity Imagescontrasting

confidence: 62%

A FEATURE MOVIE OF SiO EMISSION 20-100 AU FROM THE MASSIVE YOUNG STELLAR OBJECT ORION SOURCE I

Matthews

Greenhill

Goddi

et al. 2009

ApJ

125

201

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We present multi-epoch Very Long Baseline Array imaging of the 28 SiO v = 1 and v = 2, J = 1-0 maser emission toward the massive young stellar object (YSO) Orion Source I. Both SiO transitions were observed simultaneously with an angular resolution of ∼0.5 mas (∼0.2 AU for d = 414 pc) and a spectral resolution of ∼0.2 km s −1 . Here we explore the global properties and kinematics of the emission through two 19-epoch animated movies spanning 21 months (from 2001 March 19 to 2002 December 10). These movies provide the most detailed view to date of the dynamics and temporal evolution of molecular material within ∼20-100 AU of a massive ( 8 M ) YSO. As in previous studies, we find that the bulk of the SiO masers surrounding Source I lie in an X-shaped locus; the emission in the south and east arms is predominantly blueshifted, and emission in the north and west is predominantly redshifted. In addition, bridges of intermediate-velocity emission are observed connecting the red and blue sides of the emission distribution. We have measured proper motions of over 1000 individual maser features and found that these motions are characterized by a combination of radially outward migrations along the four main maser-emitting arms and motions tangent to the intermediate-velocity bridges. We interpret the SiO masers as arising from a wide-angle bipolar wind emanating from a rotating, edge-on disk. The detection of maser features along extended, curved filaments suggests that magnetic fields may play a role in launching and/or shaping the wind. Our observations appear to support a picture in which stars with masses as high as at least 8 M form via disk-mediated accretion. However, we cannot yet rule out that the Source I disk may have been formed or altered following a recent close encounter.

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The science case for simultaneous mm-wavelength receivers in radio astronomy

Dodson¹,

Rioja²,

Gómez³

et al. 2017

New Astronomy Reviews

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This review arose from the European Radio Astronomy Technical Forum (ERATec) meeting held in Firenze, October 2015, and aims to highlight the breadth and depth of the high-impact science that will be aided and assisted by the use of simultaneous mm-wavelength receivers. Recent results and opportunities are presented and discussed from the fields of: continuum VLBI (observations of weak sources, astrometry, observations of AGN cores in spectral index and Faraday rotation), spectral line VLBI (observations of evolved stars and massive star-forming regions) and time domain observations of the flux variations arising in the compact jets of X-ray binaries. Our survey brings together a large range of important science applications, which will greatly benefit from simultaneous observing at mm-wavelengths. Such facilities are essential to allow these applications to become more efficient, more sensitive and more scientifically robust. In some cases without simultaneous receivers the science goals are simply unachievable. Similar benefits would exist in many other high frequency astronomical fields of research.

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High resolution observations of SiO masers: Comparing the spatial distribution at 43 and 86 GHz

Cited by 69 publications

References 26 publications

VERA observations of SiO maser emission from R Aquarii

VERA observations of SiO maser emission from R Aquarii

A FEATURE MOVIE OF SiO EMISSION 20-100 AU FROM THE MASSIVE YOUNG STELLAR OBJECT ORION SOURCE I

The science case for simultaneous mm-wavelength receivers in radio astronomy

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