The Inner Nebula and Central Binary of the Symbiotic Star HM Sagittae

Eyres, S. P. S.; Bode, M. F.; Taylor, A. R.; Crocker, M. M.; Davis, R. J.

doi:10.1086/320086

Cited by 19 publications

(39 citation statements)

References 21 publications

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“…The standard scattering model requires that the orientation of the binary axis is perpendicular to the polarization angle in the blue portion of the Raman line. This is supported by the direct measurement of the orientation of the two stellar components in HM Sge by Eyres et al (2001). They found practically the same orientation as previously derived from the Raman lines (Schmid et al 2000).…”

Section: The Orientation Of the Binarysupporting

confidence: 83%

“…At present, circumstellar nebulosities are only observed for HM Sge (e.g. Eyres et al 2001) and V1016 Cyg (e.g. Brocksopp et al 2002) but future observations with improved spatial resolution will certainly reveal such nebula in other systems as well.…”

Section: The Orientation Of the Binarymentioning

confidence: 97%

“…Another manifestation of binary interaction is the presence of complicated circumstellar structures (e.g. Corradi et al 1999Corradi et al , 2001Eyres et al 2001).…”

Section: Introductionmentioning

confidence: 99%

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Orbital motion in symbiotic Mira systems

Schmid

Schild

2002

A&A

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Abstract. We present new spectropolarimetry of the Raman lines for seven symbiotic Miras, combine it with earlier data and review the polarimetric changes. All systems show slow and usually steady angular variations which are most easily interpreted as a reflection of the orbital motion. We measure angular rotation rates of typically 1 to 5• /yr. Small position angle changes are seen in Hen2-106 and RR Tel, while Hen2-38 and Hen2-127 have high rotation rates. Although our database spreads over a time span of almost 10 years, we still cover only a fraction of a typical D-type orbit. Since we expect elliptical orbits, it is too early to extrapolate to an orbital period for any individual object. In a statistical sense, however, our mean angular rotation rate shows that an average orbital period for a symbiotic Mira is 150 years. We also determine the position angle of the binary axes as projected onto the sky. Our polarimetry finally suggests that the binary axes of the systems V1016 Cyg and Hen2-38 are not far from parallel to the line of sight (conjunction), whereas the binary axes of RR Tel and AS 210 lie approximately at an angle of 90• to the line of sight.

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Section: The Orientation Of the Binarysupporting

confidence: 83%

Section: The Orientation Of the Binarymentioning

confidence: 97%

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Orbital motion in symbiotic Mira systems

Schmid

Schild

2002

A&A

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“…The orbital period is unknown, likely higher than ∼100 yr. Eyres et al (2001) measured the binary component positions using HST images, and estimated a projected binary separation of 40 ± 9 mas and a position angle of the binary axis of 130 ± 10 degrees, in agreement with what is suggested by Schmid et al (2000) based on spectropolarimetry. Unfortunately, the distance to HM Sge is rather uncertain -the published values range from 0.3 to 3.2 kpc (e.g.…”

Section: Introductionsupporting

confidence: 85%

CO observations of symbiotic stellar systems

Bujarrabal

Mikołajewska

Quintana-Lacaci

2010

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Aims. We have studied the molecular content of the circumstellar environs of symbiotic stellar systems, in particular of the well know objects R Aqr and CH Cyg. The study of molecules in these stars will help for understanding the properties of the very inner shells around the cool stellar component from which molecular emission is expected to come. Methods. We performed mm-wave observations with the IRAM 30 m telescope of the 12 CO J = 1−0 and J = 2−1, 13 CO J = 1−0 and J = 2−1, and SiO J = 5−4 transitions in the symbiotic stars R Aqr, CH Cyg, and HM Sge. The data were analyzed by means of a simple analytical description of the general properties of molecular emission from the inner shells around the cool star. Numerical calculations of the expected line profiles were also performed that took the level population and radiative transfer under such conditions into account. Results. Weak emission of 12 CO J = 1−0 and J = 2−1 was detected in R Aqr and CH Cyg and a good line profile of 12 CO J = 2−1 in R Aqr was obtained. The intensities and profile shapes of the detected lines are compatible with emission coming from a very small shell around the Mira-type star, with a radius comparable to or slightly smaller than the distance to the hot dwarf companion, 10 14 −2 × 10 14 cm. We argue that other possible explanations are improbable. This region probably shows properties similar to those characteristic of the inner shells around standard AGB stars: outwards expansion at about 5-25 km s −1 , with a significant acceleration of the gas, temperatures decreasing with radius between about 1000 and 500 K, and densities ∼10 9 −3 × 10 8 cm −3 . Our model calculations are able to explain the asymmetric line shape observed in 12 CO J = 2−1 from R Aqr, in which the relatively weaker blue part of the profile would result from selfabsorption by the outer layers (in the presence of a velocity increase and a temperature decrease with radius). The mass-loss rates are somewhat higher than in standard AGB stars, as often happens for symbiotic systems. In R Aqr, we find that the total mass of the CO emitting region is ∼2−3 × 10 −5 M , corresponding toṀ ∼ 5 × 10 −6 −10 −5 M yr −1 and compatible with results obtained from dust emission. Considering other existing data on molecular emission, we suggest that the limited extent of the molecule-rich gas in symbiotic systems is mainly due to molecule photodissociation by the radiation of the hot dwarf star.

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“…• according to Eyres et al 2001;Schmid et al 2000) located beyond the window at 40 mas north-west . The MIDI baselines at PA ∼ 45…”

Section: Departure From Spherical Symmetrymentioning

confidence: 99%

A compact dust shell in the symbiotic system HM Sagittae

Sacuto¹,

Chesneau²,

Vannier³

et al. 2007

A&A

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Aims. We present high spatial resolution observations of the mid-infrared core of the dusty symbiotic system HM Sge. Methods. The MIDI interferometer was used with the VLT Unit Telescopes and Auxiliary Telescopes providing baselines oriented from PA = 42• to 105• . The MIDI visibilities are compared with the ones predicted in the frame of various spherical dust shells published in the literature involving single or double dusty shells intended to account for the influence of the hot White Dwarf.Results. The mid-IR environment is unresolved by a 8 m telescope (resolution ∼ 300 mas) and the MIDI spectrum exhibits a level similar to the ISO spectra recorded 10 yr ago. The estimated Gaussian Half Width at Half Maximum of the shell of 7.8 ± 1.3 mas (12 AU, assuming a distance of 1.5 kpc) in the 8-9 µm range, and 11.9 ± 1.3 mas (18 AU) in the 11-12 µm range, are much smaller than the angular separation between the Mira and the White Dwarf of 40 mas (60 AU). The discrepancies between the HWHM at different angle orientations suggest an increasing level of asymmetry from 13 to 8 µm. The observations are surprisingly well fitted by the densest (optically thick in the N band) and smallest spherical model published in the literature based on the ISO data, although such a model does not account for the variations of near-IR photometry due to the Mira pulsation cycle suggesting a much smaller optical thickness. These observations also discard the two shells models, developed in an attempt to take into account the effect of the White Dwarf illumination onto the dusty wind of the Mira. These models are too extended, and lead to a level of asymmetry of the dusty environment tightly constrained by the MIDI visibilities. These observations show that a high rate of dust formation is occurring in the vicinity of the Mira which seems to be not highly perturbed by the hot companion.

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The Inner Nebula and Central Binary of the Symbiotic Star HM Sagittae

Cited by 19 publications

References 21 publications

Orbital motion in symbiotic Mira systems

Orbital motion in symbiotic Mira systems

CO observations of symbiotic stellar systems

A compact dust shell in the symbiotic system HM Sagittae

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