A warped m= 2 water maser disc in V778 Cyg?

Babkovskaia, Natalia; Poutanen, Juri; Richards, A. M. S.; Szczerba, R.

doi:10.1111/j.1365-2966.2006.10626.x

Cited by 8 publications

(10 citation statements)

References 25 publications

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“…) obtained highresolution 22 GHz H 2 O maser maps toward the silicate carbon star V778 Cyg using MERLIN and VLBA, respectively. The H 2 O maser distributions are linearly aligned with a slightly Sshaped structure, which Szczerba et al (2006) and Babkovskaia et al (2006) interpret as a warped circum-companion disk viewed almost edge-on. Therefore, as discussed in Yamamura et al (2000) and Ohnaka et al (2006), there may be two classes of silicate carbon stars: systems with optically thick circumbinary disks and those with circum-companion disks.…”

Section: Introductionmentioning

confidence: 89%

Imaging the oxygen-rich disk toward the silicate carbon star EU Andromedae

Ohnaka¹,

Boboltz²

2007

A&A

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Context. Silicate carbon stars are characterized by oxygen-rich circumstellar environments as revealed by prominent silicate emission, despite their carbon-rich photospheres. While the presence of a circumbinary disk or a disk around an unseen, low-luminosity companion has been suggested to explain the peculiar dust chemistry, the origin of silicate carbon stars is still a puzzle to date. Aims. We present multi-epoch, high-angular resolution observations of 22 GHz H 2 O masers toward the silicate carbon star EU And to probe the spatio-kinematic distribution of oxygen-rich material. Methods. EU And was observed at three epochs (maximum time interval of 14 months) with the Very Long Baseline Array (VLBA). Results. Our VLBA observations of the 22 GHz H 2 O masers have revealed that the maser spots are distributed along a straight line across ∼20 mas, with a slight hint of an S-shaped structure. The observed spectra show three prominent velocity components at V LSR = −42, −38, and −34 km s −1 , with the masers in SW redshifted and those in NE blueshifted. The maser spots located in the middle of the overall distribution correspond to the component at V LSR = −38 km s −1 , which approximately coincides with the systemic velocity. These observations can be interpreted as either an emerging helical jet or a disk viewed almost edge-on (a circumbinary or circum-companion disk). However, the outward motion measured in the VLBA images taken 14 months apart is much smaller than what is expected from the jet scenario. Furthermore, the mid-infrared spectrum obtained with the Spitzer Space Telescope indicates that the 10 µm silicate emission is optically thin and the silicate grains are of sub-micron size. This lends support to the presence of a circum-companion disk, because an optically thin circumbinary disk consisting of such small grains would be blown away by the intense radiation pressure of the primary (carbon-rich) star. If we assume Keplerian rotation for the circum-companion disk, the mass of the companion is estimated to be 0.5-0.8 M . We also identify CO 2 emission features at 13-16 µm in the Spitzer spectrum of EU And-the first unambiguous detection of CO 2 in silicate carbon stars.

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Section: Introductionmentioning

confidence: 89%

Imaging the oxygen-rich disk toward the silicate carbon star EU Andromedae

Ohnaka¹,

Boboltz²

2007

A&A

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“…If we adopt 0.5-0.8 M for the companion mass as in EU And (Ohnaka & Boboltz 2008) and assume the Keplerian rotation, the radius of the maser emitting region is estimated to be 10-32 AU. Adopting a higher mass of 1.7 M derived for V778 Cyg by Babkovskaia et al (2006) leads to a radius of 68 AU for the rotational velocity of 5 km s −1 . Because the velocity separations estimated from the past and present maser spectra are still a lower limit, the estimated projected rotational velocities are a lower limit.…”

Section: Resultsmentioning

confidence: 99%

“…First, the orbital period is expected to be as long as a few hundred years. For example, the modeling of the masers toward V778 Cyg by Babkovskaia et al (2006) suggests a mass of 1 M and 1.7 M for the primary star and the companion, respectively, with a separation of 80 AU. This translates into an orbital velocity of ∼2 km s −1 and a period of ∼440 years.…”

Section: Resultsmentioning

confidence: 99%

VLA survey of 22 GHz H₂O masers toward ten silicate carbon stars

Ohnaka

Boboltz

Mulitz-Schimel

et al. 2013

A&A

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Context. Despite their carbon-rich photospheres, silicate carbon stars show evidence of oxygen-rich circumstellar material, which is thought to exist in disks. Silicate carbon stars represent interesting cases that allow us to study the possible effects of binarity on stellar evolution and mass loss accompanied by the formation of disks. Aims. We present a small survey of 22 GHz H 2 O masers toward ten silicate carbon stars with much better sensitivity than is the case for previous observations. Methods. We observed our sample with the Karl G. Jansky Very Large Array (VLA) using the most expanded configuration (A-configuration) with a maximum baseline of 36 km. For some of our program stars with noisy Infrared Astronomical Satellite (IRAS) Low Resolution Spectra (LRS), we present new mid-IR spectra obtained with the Very Large Telescope Interferometer and the Spitzer Space Telescope. Results. We detected H 2 O masers toward five out of ten silicate carbon stars (EU And, V778 Cyg, IRAS 06017+1011, V1415 Cyg, and NC83 = V1945 Cyg), with NC83 being a new detection. No H 2 O masers were detected toward BM Gem, IRAS 07221-0431, IRAS 08002-3803, IRAS 18006-3213, and HD 189605. The velocity separation between the most blue-and red-shifted maser features is 10-14 km s −1 . If we assume that the masers originate in circum-companion disks, the measured velocity separations translate into a lower limit of the rotational velocity of 5-7 km s −1 , and the upper limit of the radius of the maser emitting region is estimated to be 10-68 AU for a companion mass of 0.5-1.7 M . The new mid-IR spectra of NC83, IRAS 06017+1011, and HD 189605 confirm the 10 μm silicate emission. The latter two stars show a bump at ∼11.5 μm, which is presumably due to SiC originating in the ongoing mass loss from the carbon-rich primary star, not due to crystalline silicate. We also report on the detection of the UV flux at 2271 Å toward HD 189605.

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“…The dynamical age of the jets is very young (< 35−100 years) and only a handful of such sources are known, consistent with this dynamical age. This rare class of "water fountain" sources is described in separate review papers in these proceedings by Imai and Vlemmings. A particularly unusual and rare source studied by Babkovskaia et al (2006); Szczerba et al (2006) presents water masers in a warped disk around a companion to the SiC star V778 Cyg.…”

Section: Some Of These Science Questions Have Been Explored In Recentmentioning

confidence: 99%

Stellar masers, circumstellar envelopes and supernova remnants

Kemball

2007

Proc. IAU

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This paper reviews recent advances in the study or circumstellar masers and masers found toward supernova remnants. The review is organized by science focus area, including the astrophysics of extended stellar atmospheres, stellar mass-loss processes and outflows, late-type evolved stellar evolution, stellar maser excitation and chemistry, and the use of stellar masers as independent distance estimators. Masers toward supernova remnants are covered separately. Recent advances and open future questions in this field are explored.

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A warped m= 2 water maser disc in V778 Cyg?

Cited by 8 publications

References 25 publications

Imaging the oxygen-rich disk toward the silicate carbon star EU Andromedae

Imaging the oxygen-rich disk toward the silicate carbon star EU Andromedae

VLA survey of 22 GHz H₂O masers toward ten silicate carbon stars

Stellar masers, circumstellar envelopes and supernova remnants

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A warped m= 2 water maser disc in V778 Cyg?

Cited by 8 publications

References 25 publications

Imaging the oxygen-rich disk toward the silicate carbon star EU Andromedae

Imaging the oxygen-rich disk toward the silicate carbon star EU Andromedae

VLA survey of 22 GHz H2O masers toward ten silicate carbon stars

Stellar masers, circumstellar envelopes and supernova remnants

Contact Info

Product

Resources

About

VLA survey of 22 GHz H₂O masers toward ten silicate carbon stars