The effect of dust obscuration in RR Telescopii on optical and IR long-term photometry and Fe II emission lines

Kotnik-Karuza, Dubravka; Friedjung, M.; Whitelock, P. A.; Marang, F.; Exter, Katrina; Keenan, F. P.; Pollacco, D. L.

doi:10.1051/0004-6361:20054190

Cited by 13 publications

(22 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The remainder contain Mira variables in which near-IR observations show a reddened Mira component surrounded by circumstellar dust at a temperature of about 1000 K. These symbiotics with warm dust shells are classified as D-type symbiotics (Mikolajewska et al 1988;Kenyon 1986). The warm thick dust shell is usually responsible for the nearinfrared excess and obscuration events, most likely caused by a change in optical depth of the dust envelope (Kotnik-Karuza et al 2006;Whitelock 2003).…”

Section: Introductionmentioning

confidence: 99%

Modelling of dust around the symbiotic Mira RR Telescopii during obscuration epochs

Jurkić

Kotnik-Karuza

2012

A&A

Self Cite

View full text Add to dashboard Cite

Context. Symbiotic Miras represent a class of peculiar binaries whose nature is still not well understood. Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding the evolution of symbiotic binaries and the interaction between their components. We present a model of inner dust regions around the cool Mira component of the symbiotic nova RR Tel based on the near-IR terrestrial photometry and infrared ISO spectra. Aims. Our goal is to find a comprehensive and consistent model of the circumstellar inner dust regions around the Mira component that can explain the observed photometric and spectroscopic features in the near-and mid-infrared. Methods. Available JHKL photometric observations from South African Astronomical Observatory were collected and corrected for Mira pulsations as well as for interstellar reddening to follow temporal changes of the near-infrared colours. Spectral energy distributions (SEDs) from 1 to 13 μm during obscuration epoch were reconstructed with the simultaneously available ISO/SWS spectra and JHKL magnitudes. The dust properties were determined by modelling both the reconstructed SEDs and the near-IR colours using the DUSTY numerical code. This 1D code solves radiative transfer through the circumstellar dust by calculating the dust temperature profile assuming spherical symmetry. Results. The Mira pulsation period of 387 days was found and confirmed with two independent fitting methods. A long-term variation of ∼7000 days, which cannot be attributed to orbital motion, was obtained from the analysis of the near-IR magnitudes. Reconstructed infrared SEDs were modelled successfully by a single dust shell with dust distribution enhanced by radiatively driven stellar winds. Mira temperature, dust sublimation temperature, grain diameter, density distribution, and optical depth have been obtained. Our model shows a maximum dust grain diameter of 4 μm, which is larger than expected and can be explained by grain growth in conditions of increased mass loss during obscuration epochs. Obscurations in the near-IR can be understood as a result of change of the dust optical depth and of the mass loss rate of Mira component. Change of the dust temperature on the inner boundary of the dust shell with pulsation phase have been identified by SED modelling. Assuming a gas-to-dust ratio of 200, we found a variable mass loss rate between 2.3 and 9.0 × 10 −6 M /yr and estimated the distance to RR Tel to be 2.7 kpc. Our results suggest a relatively low influence of the hot component on circumstellar dust and strong shielding of dust from the UV flux.

show abstract

Section: Introductionmentioning

confidence: 99%

Modelling of dust around the symbiotic Mira RR Telescopii during obscuration epochs

Jurkić

Kotnik-Karuza

2012

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…We have used all available published JHKL magnitudes from the South African Astronomical Observatory (Gromadzki et al 2009), corrected for Mira pulsations and interstellar reddening using our own developed algorithm. The JHKL light curves show three distinct obscuration intervals (Kotnik-Karuza et al 2006). Spectral energy distributions during and outside obscuration epochs were reconstructed using ISO short wavelength infrared spectra together with the near-IR JHKL observations at three epochs when both JHKL magnitudes and ISO spectra were simultaneously available.…”

Section: Observational Data and Dusty Codementioning

confidence: 99%

“…Around 20% of symbiotic stars, called D-type symbiotics, consist of a Mira component with a circumstellar dust shell at the temperature of around 1000 K (Mikolajewska et al 1988, Kenyon 1986. Obscuration events in the near-IR seen in most of the D-type symbiotics are probably caused by a change in optical depth of the dust shell (Kotnik-Karuza et al 2006, Whitelock 2003.…”

Section: Introductionmentioning

confidence: 99%

“…A complete model of the circumstellar dust environment around RR Tel capable of explaining all near and mid-IR spectroscopic and photometric features is still to be found. Up to now, most attempts to explain the circumstellar dust environment have included only simple thick dust shell models acting as a blackbody, without determination of any physical dust properties (Kotnik-Karuza et al 2006, Whitelock 1987. The recent colliding wind model of Angeloni et al (2010) has proposed the existence of two blackbody dust shells at 400 K and 1000 K, with maximum emission of the 400 K dust shell at around 10 microns, typical for silicate emission.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Modeling of Circumstellar Dust by the DUSTY Code

Jurkić

Kotnik-Karuza

2011

Proc. IAU

View full text Add to dashboard Cite

Abstract. We present a circumstellar dust model around the symbiotic Mira RR Tel obtained by modeling the near-infrared JHKL magnitudes and ISO spectra. In order to follow the evolution of infrared colours in time, the published JHKL magnitudes were corrected by removing the Mira pulsations. The RR Tel light curves show three obscuration events in the near-IR. Using the simultaneously available JHKL magnitudes and ISO spectra in three different epochs, we obtained SEDs in the near-and mid-IR spectral region (1-20 µm) in epochs with and without obscuration.The DUSTY numerical code was used to solve the radiative transfer and to determine the circumstellar dust properties of the inner dust regions around the Mira, assuming a spherical dust temperature distribution in its close neighbourhood. The physical properties of the dust, mass loss and optical depth during intervals with and without obscuration have been obtained. Both JHKL and ISO observations during the obscuration period can be reproduced with a spherical dust envelope, while ISO spectra outside obscuration show a different behaviour. The dynamical behaviour of the circumstellar dust was obtained by modeling the JHKL magnitudes observed during the span of more than 30 years.The DUSTY code was also successfully applied in the modeling of circumstellar dust envelopes of young stellar objects, such as Herbig Ae/Be stars.

show abstract

“…Kotnik-Karuza et al (2006) have recently estimated its distance to be 2.5 kpc. Although it is one of the most studied symbiotic systems, many of the physical parameters defining RR Tel are still uncertain, including the orbital period of the system.…”

Section: Rr Telmentioning

confidence: 99%

Modeling of C IV pumped fluorescence of Fe II in symbiotic stars

Eriksson

Nilsson

Veenhuizen³

et al. 2007

A&A

View full text Add to dashboard Cite

Aims. We describe how the C iv λ1548.18 line pumps the 1548.20 and 1548.41 Å channels of Fe ii in symbiotic stars through the process known as photo-ionization by accidental resonance (PAR). We describe where and why Fe ii fluorescence arises in symbiotic stars and whether the Fe ii λ1548.41 channel can only be activated when there is a white-dwarf wind present in the system. Further, we aim to show how an analysis of the PAR-pumped lines helps to understand the phyisical conditions that they manifest.Methods. We calculate intensities of the C iv-pumped Fe ii fluorescence lines in symbiotic stars, corresponding to the y 4 H 11/2 and w 2 D 3/2 levels, based on a simple geometrical model of the emitting regions. We apply the model to seven symbiotic stars, known to have Fe ii fluorescence lines pumped by C iv in their spectra. We compare the predicted intensities to the observed intensities of the selected symbiotic stars. Results. We find that we can reproduce the observed fluorescence intensities of the seven symbiotic stars in our sample, using parameters that are consistent with their known properties. We show that PAR-produced lines can be used as a diagnostic tool to derive important physical parameters of a stellar system. We suggest that the detection of Fe ii lines corresponding to the w 2 D 3/2 level in certain symbiotic stars provide evidence of hot shells expanding with velocities of at least hundreds km s −1 in those systems.

show abstract

The effect of dust obscuration in RR Telescopii on optical and IR long-term photometry and Fe II emission lines

Cited by 13 publications

References 27 publications

Modelling of dust around the symbiotic Mira RR Telescopii during obscuration epochs

Modelling of dust around the symbiotic Mira RR Telescopii during obscuration epochs

Modeling of Circumstellar Dust by the DUSTY Code

Modeling of C IV pumped fluorescence of Fe II in symbiotic stars

Contact Info

Product

Resources

About