Spatial Resolution of the R Aquarii Binary System

Hollis, J. M.; Pedelty, J. A.; Lyon, Richard G.

doi:10.1086/310687

Cited by 41 publications

(68 citation statements)

References 16 publications

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“…Rotation kinematics may be a transient or strongly variable phenomenon, perhaps related to the possible binary periastron by 1996 proposed by McIntosh & Rustan (2007); but note that the periastron date is very controversial, see Hollis et al (1997Hollis et al ( , 2001), Gromadzki & Mikołajewska (2009). We favor, however, that the spot positions and velocities observed in the maps during the last twelve years mainly reveal radial and random movements within the emitting shell.…”

Section: Discussionmentioning

confidence: 74%

“…Although the orbital parameters of the binary system are still controversial, we can expect the time of apastron to be around 2001, adopting the oribital parameters estimated by Gromadzki & Mikolajewska (2009), who propose a time of periastron passage T 0 = 1979.40 ± 1.99 yr and a period of the orbit P orb = 43.64 ± 1.29 yr. The binary components of R Aqr were resolved by Hollis et al (1997) in November 1996. These data revealed that the Mira-like variable was located in the south of the system and the hot dwarf star was located in the north.…”

Section: Measurements Of the Parallax And Proper Motions Of R Aqrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The two components have been resolved in observations by Hollis et al (1997), who conclude that the projection of the orbit axis on the plane of the sky presents a PA ∼ 0 • (the direction of the line of the nodes being placed at about 90 degrees, roughly in the plane of optical nebulosity). The orbit is characterized by a distance between stars of about 2 × 10 14 cm and a period of about 44 yr (Hollis et al 1997;McIntosh & Rustan 2007). The direction of the orbit axis is, however, controversial due to difficult interpretation of the data and the uncertainty in the distance; see recent discussion by Gromadzki & Mikołajewska (2009), who propose that the orbit axis is mostly parallel to the optical jets.…”

Section: Introductionmentioning

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: Discussionmentioning

confidence: 74%

Section: Measurements Of the Parallax And Proper Motions Of R Aqrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

VERA observations of SiO maser emission from R Aquarii

Kamohara¹,

Bujarrabal²,

Honma³

et al. 2010

A&A

View full text Add to dashboard Cite

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“…The binary has been spatially resolved and a preliminary orbit (with a period of ∼ 44 yrs) derived in [106,66]. The system is embedded in a complex bipolar nebula with jets ( [53] and references therein).…”

Section: =R Aqrmentioning

confidence: 99%

A catalogue of symbiotic stars

Belczyński

Mikołajewska

Munari

et al. 2000

Astron. Astrophys. Suppl. Ser.

377

407

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Abstract. We present a new catalogue of symbiotic stars. In our list we include 188 symbiotic stars as well as 30 objects suspected of being symbiotic. For each star, we present basic observational material: coordinates, V and K magnitudes, ultraviolet (UV), infrared (IR), X-ray and radio observations. We also list the spectral type of the cool component, the maximum ionization potential observed, references to finding charts, spectra, classifications and recent papers discussing the physical parameters and nature of each object. Moreover, we present the orbital photometric ephemerides and orbital elements of known symbiotic binaries, pulsational periods for symbiotic Miras, Hipparcos parallaxes and information about outbursts and flickering.

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VLBI phase-referencing observations of SiO masers towards R Aquarii

Kamohara

2007

Proc. IAU

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Spatial Resolution of the R Aquarii Binary System

Cited by 41 publications

References 16 publications

VERA observations of SiO maser emission from R Aquarii

VERA observations of SiO maser emission from R Aquarii

A catalogue of symbiotic stars

VLBI phase-referencing observations of SiO masers towards R Aquarii

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