<i>JHK</i> photometry of symbiotic stars

Kamath, U. S.; Ashok, N. M.

doi:10.1051/aas:1999171

Cited by 15 publications

(14 citation statements)

References 11 publications

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“…However they differ from the mean estimates of Taranova by an amount greater than our observational error. They differ also from some of the JHK estimates of Kamath & Ashok (1999). The study of the quiescent variability of Z And is not a task for our consideration.…”

Section: The Quiescent Phasementioning

confidence: 78%

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Mass ejection by the symbiotic binary Z And during its 2000–2002 outburst

Tomov

Taranova²,

Tomova

2003

A&A

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Abstract. Broad-band UBV JHKLM data have been obtained at the time of the quiescent orbital photometric maximum of the classical symbiotic binary system Z And and at some epochs of its 2000-2002 active phase. The data of the active phase are related to the time of the optical maximum and after it when the star was returning to quiescence. Broad-band quiescent RI photometry from the literature was also used to obtain the parameters of the cool component of this binary. All of these data suggest that the hot compact component has undergone a major expansion and the emission measure of the circumbinary nebula has also increased. Some mechanisms for interpretation of the outburst are reviewed.

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Section: The Quiescent Phasementioning

confidence: 78%

“…The Z And system has been observed photometrically in the IR spectral region by Eiroa et al (1982), Munari et al (1992), Kamath & Ashok (1999) and Taranova (2000). Taranova (2000) has obtained mean estimates in the period 1978-1999 which are J = 6. m 34, H = 5. m 29, K = 5. m 06, L = 4. m 62 and M = 4. m 85.…”

Section: The Quiescent Phasementioning

confidence: 98%

Mass ejection by the symbiotic binary Z And during its 2000–2002 outburst

Tomov

Taranova²,

Tomova

2003

A&A

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“…As a consequence, the S01 dust shell is more opaque than the B01 one, considering an identical dust chemical composition (warm silicate dust). B01 are satisfied with their single shell model whereas S01 think that the relatively high optical depth involved with their model (≥30 mag) is not compatible with the JHK photometry by Kamath & Ashok (1999) suggesting that the light from the Mira is not highly absorbed in near-IR. For this reason, the single shell model is rejected by S01, with the additional argument that such a model is probably simplistic in view of the disturbing presence of the hot companion.…”

Section: Single Shell Modelsmentioning

confidence: 94%

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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“…We used the spectra taken during quiescence (if available, at dates of different conjunctions of the binary components), activity and optical eclipses. Main sources of the data covering the infrared region are represented by broad-band multicolour photometric observations published by , Kamath & Ashok (1999), Taranova (2000), Glass & Webster (1973) and Feast et al (1977). Measurements in the I C and R C bands of the Cousins system were converted into the Johnson system according to Bessell (1983).…”

Section: Observationsmentioning

confidence: 99%

Disentangling the composite continuum of symbiotic binaries

Skopal¹

2005

A&A

123

250

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Abstract. We describe a method of disentangling the composite, 0.12-5 µm continuum of symbiotic binaries. The observed SED is determined by the IUE/HST archival spectra and flux-points corresponding to the optical UBVRI and infrared JHKLM photometric measurements. The modeled SED is given by superposition of fluxes from the cool giant, hot stellar source and nebula including the effect of the Rayleigh scattering process and considering influence of the iron curtain absorptions. We applied this method to 21 S-type symbiotic stars during quiescence, activity and eclipses. We isolated four main components of radiation and determined their properties. (i) Stellar radiation from the giant corresponds to a unique luminosity classnormal giants. Characteristic luminosities are 1600 ± 200 and 290 ± 30 L for red and yellow giants, respectively in our sample of objects. (ii) Hot object radiation during quiescence consists of the nebular and stellar component. The former radiates at a mean electron temperature of 19 000 K and its amount of emission suggests a mass-loss rate from giants via the wind aṫ M W = a few × 10 −7 M yr −1 . Radiation of the latter conforms well with that of a black-body photosphere at a characteristic temperature of 105 000 K. The corresponding effective radii are a factor of ∼10 larger than those of white dwarfs, which thus precludes observing the accretor's surface. Extreme cases of AX Per and V443 Her, for which the hot star temperature from the fit is not capable of producing the nebular emission, signal a disk-like structure of the hot stellar source even during quiescence. (iii) Hot object radiation during activity consists of three components -the stellar and the low-and high-temperature nebular radiation. The stellar radiation satisfies that of a black-body photosphere at a low characteristic temperature of ∼22 000 K (we call it the 1st type of outbursts) or at a very high characteristic temperature of ≈165 000 K (2nd type of outbursts). All the active objects with a high orbital inclination show features of the 1st-type of outbursts (here Z And, AE Ara, CD − 43• 14304, TX CVn, BF Cyg, CH Cyg, CI Cyg, AR Pav, AX Per), while AG Dra represents the 2nd-type. The presence of a two-temperature type of UV spectrum and an enlargement of effective radii of the stellar source by a factor of ∼10 with respect to the quiescent values during the 1st-type of outburst suggest an expansion of an optically thick medium at the orbital plane in the form of a disk. The low-temperature nebula radiates at a mean electron temperature of 14 000 K and is subject to eclipses, while the high-temperature nebula, which is seen during eclipses as the only component, is characterized by T e > 30 000 K. Radiative and geometric properties of the main sources of radiation allowed us to reconstruct a basic structure of the hot object during the 1st-type of outburst. There is an edge-on disk around the accretor. Its outer flared rim represents a warm pseudophotosphere of the hot stellar source, whose radiation is Rayleigh atten...

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JHK photometry of symbiotic stars

Cited by 15 publications

References 11 publications

Mass ejection by the symbiotic binary Z And during its 2000–2002 outburst

Mass ejection by the symbiotic binary Z And during its 2000–2002 outburst

A compact dust shell in the symbiotic system HM Sagittae

Disentangling the composite continuum of symbiotic binaries

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