CO observations of symbiotic stellar systems

Bujarrabal, V.; Mikołajewska, Joanna; Quintana-Lacaci, G.

doi:10.1051/0004-6361/200913743

Cited by 14 publications

(27 citation statements)

References 39 publications

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“…Figure 14 includes the lines for the expected N H 2 (r) density dependence, if the mira has a spherical mass loss ofṀ RG = 10 −5 or 10 −6 M /yr and a wind velocity of v ∞ = 10 km s −1 . Unfortunately, the mass loss rate for the mira variable in R Aqr is not well known and literature values range from aboutṀ RG = 10 −7 M /yr to 10 −5 M /yr (e.g., Mayer et al 2013;Bujarrabal et al 2010).…”

Section: Cloud Density Versus Cloud Distancementioning

confidence: 99%

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii

Schmid

Bazzon

Milli

et al. 2017

A&A

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Context. R Aqr is a symbiotic binary system consisting of a mira variable, a hot companion with a spectacular jet outflow, and an extended emission line nebula. Because of its proximity to the Sun, this object has been studied in much detail with many types of high resolution imaging and interferometric techniques. We have used R Aqr as test target for the visual camera subsystem ZIMPOL, which is part of the new extreme adaptive optics (AO) instrument SPHERE at the Very Large Telescope (VLT). Aims. We describe SPHERE/ZIMPOL test observations of the R Aqr system taken in Hα and other filters in order to demonstrate the exceptional performance of this high resolution instrument. We compare our observations with data from the Hubble Space Telescope (HST) and illustrate the complementarity of the two instruments. We use our data for a detailed characterization of the inner jet region of R Aqr. Methods. We analyze the high resolution ≈25 mas images from SPHERE/ZIMPOL and determine from the Hα emission the position, size, geometric structure, and line fluxes of the jet source and the clouds in the innermost region <2 (<400 AU) of R Aqr. The data are compared to simultaneous HST line filter observations. The Hα fluxes and the measured sizes of the clouds yield Hα emissivities for many clouds from which one can derive the mean density, mass, recombination time scale, and other cloud parameters. for the "outer" clouds around 300 AU, N e ≈ 3 × 10 6 cm −3 for the "inner" clouds around 50 AU, and even higher for the central jet source. The high N e of the clouds implies short recombination or variability timescales of a year or shorter. Conclusions. Hα high resolution data provide a lot of diagnostic information for the ionized jet gas in R Aqr. Future Hα observations will provide the orientation of the orbital plane of the binary and allow detailed hydrodynamical investigations of this jet outflow and its interaction with the wind of the red giant companion.

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Section: Cloud Density Versus Cloud Distancementioning

confidence: 99%

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii

Schmid

Bazzon

Milli

et al. 2017

A&A

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“…In a single-degenerate Type Ia progenitor system, an accreting white dwarf produces energetic UV/X-ray radiation, and thermonuclear outbursts drive shocks into the ambient CSM. A fraction of CO molecules can be dissociated by shocks or energetic photons in the dust-forming regions in these systems (Bujarrabal et al 2010 However, the near-IR excess could also be produced by metallic iron (or various iron oxides). A similar near-IR excess, with respect to models of pure silicate dust, was found by Kemper et al (2002) in their study of the O-rich AGB star OH 127.8+0.0.…”

Section: The Near-ir Excessmentioning

confidence: 99%

DUST IN A TYPE Ia SUPERNOVA PROGENITOR:SPITZERSPECTROSCOPY OF KEPLER'S SUPERNOVA REMNANT

Williams

Borkowski

Reynolds

et al. 2012

ApJ

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Characterization of the relatively poorly-understood progenitor systems of Type Ia supernovae is of great importance in astrophysics, particularly given the important cosmological role that these supernovae play. Kepler's Supernova Remnant, the result of a Type Ia supernova, shows evidence for an interaction with a dense circumstellar medium (CSM), suggesting a single-degenerate progenitor system. We present 7.5-38 µm infrared (IR) spectra of the remnant, obtained with the Spitzer Space Telescope, dominated by emission from warm dust. Broad spectral features at 10 and 18 µm, consistent with various silicate particles, are seen throughout. These silicates were likely formed in the stellar outflow from the progenitor system during the AGB stage of evolution, and imply an oxygen-rich chemistry. In addition to silicate dust, a second component, possibly carbonaceous dust, is necessary to account for the short-wavelength IRS and IRAC data. This could imply a mixed chemistry in the atmosphere of the progenitor system. However, non-spherical metallic iron inclusions within silicate grains provide an alternative solution. Models of collisionally-heated dust emission from fast shocks (> 1000 km s −1 ) propagating into the CSM can reproduce the majority of the emission associated with non-radiative filaments, where dust temperatures are ∼ 80 − 100 K, but fail to account for the highest temperatures detected, in excess of 150 K. We find that slower shocks (a few hundred km s −1 ) into moderate density material (n 0 ∼ 50 − 250 cm −3 ) are the only viable source of heating for this hottest dust. We confirm the finding of an overall density gradient, with densities in the north being an order of magnitude greater than those in the south.

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“…R Aqr is a Mira pulsator at a distance d = 214 pc, with a mass-loss rate of ∼0.5−1.0 × 10 −5 M yr −1 , and is the AGB primary star of a symbiotic binary system (Bujarrabal et al 2010). We detect emission from N = 9−8 with ALMA and show the integrated intensity map and spectrum in Fig.…”

Section: Overview Of the Samplementioning

confidence: 98%

“…7. The emission reaches a signal-to-noise ratio S /N ≈ 18 in integrated intensity, and the spectrum shows a line profile that is appropriately broadened by the HFS of AlO to a full-width at zeropower of ∼60 km s −1 , while CO emission arises from a region with wind velocities in the range 5−25 km s −1 (Bujarrabal et al 2010). From a comparison to the continuum emission, we conclude that the AlO emission coincides with the stellar position.…”

Section: Overview Of the Samplementioning

confidence: 99%

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Search for aluminium monoxide in the winds of oxygen-rich AGB stars

Beck

Decin

Ramstedt

et al. 2017

A&A

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Context. Aluminium monoxide (AlO) is likely efficiently depleted from the gas around oxygen-rich evolved stars to form alumina (Al 2 O 3 ) clusters and dust seeds. The presence of AlO gas in the extended atmospheres of evolved stars has been derived from optical spectroscopy. More recently, AlO gas was also detected at long wavelengths around the supergiant VY CMa and the oxygenrich asymptotic giant branch star o Cet (Mira A). The central role aluminium might play in dust formation and wind driving, in combination with these first detections of AlO at long wavelengths, shows the need for a wider search for this molecule in the winds of evolved stars. Aims. The detection at long wavelengths of emission in rotational transitions of AlO towards asymptotic giant branch stars can help constrain the presence and location of AlO gas in the outflows and ultimately also the efficiency of the depletion process. Methods. In search of AlO, we mined data obtained with APEX, the IRAM 30 m telescope, Herschel/HIFI, SMA, and ALMA, which were primarily aimed at studying other species around asymptotic giant branch stars. We report here on observations of AlO towards a sample of eight oxygen-rich asymptotic giant branch stars in different rotational transitions, up to seven for some stars.Results. We present definite detections of one rotational transition of AlO for o Cet and R Aqr, and tentative detections of one transition for R Dor and o Cet and two transitions for IK Tau and W Hya. The presented spectra of WX Psc, R Cas, and TX Cam show no signature of AlO. For o Cet, R Aqr, and IK Tau, we find that the AlO (N = 9−8) emission likely traces the inner parts of the wind, out to only a few tens of AU, where the gas has not yet been accelerated to its terminal velocity. This is in agreement with recently published results from a detailed study on o Cet. Conclusions. The conclusive detections of AlO emission in the case of o Cet and R Aqr confirm the presence of AlO in the gas phase in outflows of asymptotic giant branch stars. The tentative detections further support this. Since most of the observations presented in this study were obtained with stronger emission from other species than AlO in mind, observations with higher sensitivity in combination with high angular resolution will improve our understanding of the presence and behaviour of AlO. From the current data sets we cannot firmly conclude whether there is a direct correlation between the wind properties and the detection rate of AlO emission. We hope that this study can serve as a stimulus to perform sample studies in search of AlO in oxygen-rich outflows.

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CO observations of symbiotic stellar systems

Cited by 14 publications

References 39 publications

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii

DUST IN A TYPE Ia SUPERNOVA PROGENITOR:SPITZERSPECTROSCOPY OF KEPLER'S SUPERNOVA REMNANT

Search for aluminium monoxide in the winds of oxygen-rich AGB stars

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