Characterization of Dust Shell Dynamics and Asymmetry for Six Mira‐Type Stars

Tatebe, K.; Chandler, A. A.; Hale, David; Townes, C. H.

doi:10.1086/507416

Cited by 31 publications

(51 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This D-type (dusty) symbiotic system consists of a 1.0-2.0 M Mira variable and a 0.6-1.0 M white dwarf (WD) (Hollis et al 1997;Boboltz et al 1997;Tatebe et al 2006;Gromadzki & Mikołajewska 2009) that accretes matter through a disk (e.g. Hollis et al 2000).…”

Section: R Aquariimentioning

confidence: 99%

Dust and molecular shells in asymptotic giant branch stars

Zhao-Geisler

Quirrenbach

Köhler

et al. 2012

A&A

View full text Add to dashboard Cite

Context. Asymptotic giant branch (AGB) stars are one of the largest distributors of dust into the interstellar medium. However, the wind formation mechanism and dust condensation sequence leading to the observed high mass-loss rates have not yet been constrained well observationally, in particular for oxygen-rich AGB stars. Aims. The immediate objective in this work is to identify molecules and dust species which are present in the layers above the photosphere, and which have emission and absorption features in the mid-infrared (IR), causing the diameter to vary across the N-band, and are potentially relevant for the wind formation. Methods. Mid-IR (8-13 μm) interferometric data of four oxygen-rich AGB stars (R Aql, R Aqr, R Hya, and W Hya) and one carbonrich AGB star (V Hya) were obtained with MIDI/VLTI between April 2007 and September 2009. The spectrally dispersed visibility data are analyzed by fitting a circular fully limb-darkened disk (FDD). Results. The FDD diameter as function of wavelength is similar for all oxygen-rich stars. The apparent size is almost constant between 8 and 10 μm and gradually increases at wavelengths longer than 10 μm. The apparent FDD diameter in the carbon-rich star V Hya essentially decreases from 8 to 12 μm. The FDD diameters are about 2.2 times larger than the photospheric diameters estimated from K-band observations found in the literature. The silicate dust shells of R Aql, R Hya and W Hya are located fairly far away from the star, while the silicate dust shell of R Aqr and the amorphous carbon (AMC) and SiC dust shell of V Hya are found to be closer to the star at around 8 photospheric radii. Phase-to-phase variations of the diameters of the oxygen-rich stars could be measured and are on the order of 15% but with large uncertainties. Conclusions. From a comparison of the diameter trend with the trends in RR Sco and S Ori it can be concluded that in oxygen-rich stars the overall larger diameter originates from a warm molecular layer of H 2 O, and the gradual increase longward of 10 μm can be most likely attributed to the contribution of a close Al 2 O 3 dust shell. The chromatic trend of the Gaussian FWHM in V Hya can be explained with the presence of AMC and SiC dust. The observations suggest that the formation of amorphous Al 2 O 3 in oxygenrich stars occurs mainly around or after visual minimum. However, no firm conclusions can be drawn concerning the mass-loss mechanism. Future modeling with hydrostatic and self-consistent dynamical stellar atmospheric models will be required for a more certain understanding.

show abstract

Section: R Aquariimentioning

confidence: 99%

Dust and molecular shells in asymptotic giant branch stars

Zhao-Geisler

Quirrenbach

Köhler

et al. 2012

A&A

View full text Add to dashboard Cite

show abstract

“…The object W Aql is a Mira variable with a period of 490 days and an amplitude of approximately 7 mag, ranging from 7.3 to 14.3 mag in the V band. Due to its variable nature, many different distance calculations have been made for W Aql (Danchi et al 1994;Groenewegen 1998;Tatebe et al 2006;Ramstedt et al 2009). At a distance of 400 pc (Whitelock et al 2008), this separation corresponds to 190 AU.…”

Section: Introductionmentioning

confidence: 99%

“…This would certainly cause extinction depending on the alignment of the system. Tatebe et al (2006) used the UC Berkeley Infrared Spatial Interferometer to resolve the distribution of emitting dust at 11.15 µm and found an asymmetry in the dust distribution around the primary on small scales (hundreds of mas), while Ramstedt et al (2011) find asymmetry on large scales (10 arcsec). Herschel/PACS photometry presented in Mayer et al (2013) shows a large (∼100 arcsec) dust envelope on the same general shape as Ramstedt et al (2011) found in the optical but with an bright patch of dust to the east of the star in both the 70 µm and 160 µm images.…”

Section: Introductionmentioning

confidence: 99%

Classifying the secondary component of the binary star W Aquilae

Danilovich

Olofsson

Black

et al. 2015

A&A

View full text Add to dashboard Cite

Aims. The object W Aql is an asymptotic giant branch (AGB) star with a faint companion. By determining more carefully the properties of the companion, we hope to better constrain the properties of the AGB star. Methods. We present new spectral observations of the binary star W Aql at minimum and maximum brightness and new photometric observations of W Aql at minimum brightness. Results. The composite spectrum near minimum light is predominantly from the companion at wavelengths λ < 6000 Å. This spectrum can be classified as F8 to G0, and the brightness of the companion is that of a dwarf star. Therefore, it can be concluded that the companion is a main sequence star. From this, we are able to constrain the mass of the AGB component to 1.04-3 M and the mass of the W Aql system to 2.1-4.1 M . Our photometric results are broadly consistent with this classification and suggest that the main sequence component suffers from approximately 2 mag of extinction in the V band primarily due to the dust surrounding the AGB component.

show abstract

“…Observations of such small structures near evolved stars can only be performed with the use of high-angular resolution techniques like the infrared Very Large Telescope Interferometer (VLTI), i.e. planetary nebulae (Chesneau et al , 2007Lagadec et al 2006); VLTP star (Chesneau et al 2009); Mira stars (Tatebe et al 2006(Tatebe et al , 2007(Tatebe et al , 2008; carbon stars (Ohnaka & Boboltz 2008;Sacuto et al 2011;Deroo et al 2007b); OH/IR stars (Deroo et al 2007a,b;Chesneau et al 2005b); post-AGB stars (Deroo et al 2006;Matsuura et al 2006); proto-planetary nebulae (Murakawa et al 2008;Ohnaka et al 2006). Two of the best-studied examples of elongated and axisymmetric bipolar planetary nebulae are M2-9 and Menzel 3.…”

Section: Introductionmentioning

confidence: 99%

A disc inside the bipolar planetary nebula M2-9

Lykou

Chesneau

Zijlstra

et al. 2011

A&A

View full text Add to dashboard Cite

Aims. Bipolarity in proto-planetary and planetary nebulae is associated with events occurring in or around their cores. Past infrared observations have revealed the presence of dusty structures around the cores, many in the form of discs. Characterising those dusty discs provides invaluable constraints on the physical processes that govern the final mass expulsion of intermediate mass stars. We focus this study on the famous M2-9 bipolar nebula, where the moving lighthouse beam pattern indicates the presence of a wide binary. The compact and dense dusty core in the centre of the nebula can be studied by means of optical interferometry. Methods. M2-9 was observed with VLTI/MIDI at 39-47 m baselines with the UT2-UT3 and UT3-UT4 baseline configurations. These observations are interpreted using a dust radiative transfer Monte Carlo code. Results. A disc-like structure is detected perpendicular to the lobes, and a good fit is found with a stratified disc model composed of amorphous silicates. The disc is compact, 25 × 35 mas at 8 μm and 37 × 46 mas at 13 μm. For the adopted distance of 1.2 kpc, the inner rim of the disc is ∼15 AU. The mass represents a few percent of the mass found in the lobes. The compactness of the disc puts strong constraints on the binary content of the system, given an estimated orbital period 90-120 yr. We derive masses of the binary components between 0.6-1.0 M for a white dwarf and 0.6-1.4 M for an evolved star. We present different scenarios on the geometric structure of the disc accounting for the interactions of the binary system, which includes an accretion disc as well.

show abstract

Characterization of Dust Shell Dynamics and Asymmetry for Six Mira‐Type Stars

Cited by 31 publications

References 37 publications

Dust and molecular shells in asymptotic giant branch stars

Dust and molecular shells in asymptotic giant branch stars

Classifying the secondary component of the binary star W Aquilae

A disc inside the bipolar planetary nebula M2-9

Contact Info

Product

Resources

About