The nascent wind of AGB star R doradus: evidence for a recent episode of enhanced mass loss

Nhung, P. T.; Hoai, D. T.; Tuan-Anh, P.; Darriulat, P.; Diep, P. N.; Phượng, Nguyễn Thị Kim; Thai, T. T.

doi:10.1093/mnras/stz2675

Cited by 8 publications

(24 citation statements)

References 20 publications

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“…We note the presence of an enhancement of emissivity near the line of sight in the lower |V z | intervals of the blue-shifted hemisphere, suggesting the presence of another component closer to the region of the slow wind. While the global picture is dominated by the former, which extends down to −20 km s −1 with intensity comparable to the red-shifted component, the presence of this enhancement cannot be ignored and needs to be studied in relation with the complex morphokinematics of the slow wind [27]. However, this is beyond the scope of the present work that focuses on the dominant large Doppler velocity components.…”

Section: Iii1 Interpretation In Terms Of Gas Streamsmentioning

confidence: 89%

“…The SO data (time on source of 2.7 hours) are from project 2017.1.00824.S observed in December 2017 in band 6 with an average of 45 antennas. They have been used by Nhung et al [27] to study the slow wind using the calibrations and deconvolution provided by the standard ALMA pipeline. We have checked the quality of the data reduction and evidence for the Gaussian distribution of the noise and for the proper description of the continuum map is given there, together with channel maps.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…We have checked the quality of the data reduction and evidence for the Gaussian distribution of the noise and for the proper description of the continuum map is given there, together with channel maps. These data have not been used by other authors and the study of Nhung et al [27] does not address the issue of large Doppler velocity components.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

“…In addition, below ∼15 au, the analyses of Danilovich et al [24], De Beck & Olofsson [25] and Van de Sande et al [26] have contributed a considerable amount of detailed information of relevance to the physico-chemistry and dynamics of both dust and gas. At larger distances from the star, an analysis of ALMA observations of SO(J K = 6 5 − 5 4 ) emission [27], probing distances between 20 and 100 au, gives evidence for the wind to host a radial outflow covering large solid angles and displaying strong inhomogeneity both in direction and radially: the former takes the form of multiple cores and the latter displays a radial dependence suggesting an episode of enhanced mass loss having occurred a century or so ago.…”

Section: Introductionmentioning

confidence: 99%

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Observation of High Doppler Velocity Wings in the Nascent Wind of R Doradus

Do¹,

Pham²,

Tuan-Anh³

et al. 2020

Comm. in Phys.

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We study the morpho-kinematics in the nascent wind of AGB star R Doradus in the light of high Doppler velocity wings observed in the spectral lines of several species. We probe distances from the star between ∼10 and ∼100 au using ALMA observations of the emission of five different molecular lines. High Doppler velocity enhancements of the line emission are observed in the vicinity of the line of sight crossing the star, reminiscent of those recently interpreted as gas streams in the nascent wind of a similar AGB star, EP Aqr. They are present in both blue-shifted and red- shifted hemispheres but are not exactly back-to-back. They are accelerated at a typical rate of 0.7 km s\(^{−1}\) au\(^{−1}\) up to some 20 km s\(^{−1}\). Important differences are observed between the emissions of different molecules. We exclude an effect of improper continuum subtraction. However, in contrast to EP Aqr, the line of sight plays no particular role in the R Dor morpho-kinematics, shedding doubt on the validity of a gas stream interpretation. We discuss possible interpretations in terms of stellar pulsations or of rotation of the gas in the environment of the star. We conclude that, in the state of current knowledge, no fully convincing picture of the physics governing the production of such high velocities, typically twice as large as the terminal velocity, can be reliably drawn. New high resolution analyses of observations of the nascent wind of oxygen-rich AGB stars are needed to clarify the issue.

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Section: Iii1 Interpretation In Terms Of Gas Streamsmentioning

confidence: 89%

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Observations and Data Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Observation of High Doppler Velocity Wings in the Nascent Wind of R Doradus

Do¹,

Pham²,

Tuan-Anh³

et al. 2020

Comm. in Phys.

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show abstract

“…In addition, below ~15 au, the analyses of Danilovich et al [16] chemistry and dynamics of both dust and gas. At larger distances from the star, an analysis of ALMA observations of SO(J K =6 5 −5 4 ) emission [36], probing distances between 20 and 100 au, gives evidence for the wind to host a radial outflow covering large solid angles and displaying strong inhomogeneity both in direction and radially: the former takes the form of multiple cores and the latter displays a radial dependence suggesting an episode of enhanced mass loss having occurred a century or so ago.…”

Section: R Dormentioning

confidence: 99%

On the origin of high Doppler velocity wings in the spectra of O-rich AGB stars

et al. 2020

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Molecules, shocks, and disk in the axi-symmetric wind of the MS-type AGB star RS Cancri

Winters

Hoai

Wong

et al. 2022

A&A

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Context. The latest evolutionary phases of low- and intermediate-mass stars are characterized by complex physical processes like turbulence, convection, stellar pulsations, magnetic fields, condensation of solid particles, and the formation of massive outflows that inject freshly produced heavy elements and dust particles into the interstellar medium. Aims. By investigating individual objects in detail, we wish to analyze and disentangle the effects of the interrelated physical processes on the structure of the wind-forming regions around them. Methods. We use the Northern Extended Millimeter Array to obtain spatially and spectrally resolved observations of the semi-regular asymptotic giant branch (AGB) star RS Cancri and apply detailed 3D reconstruction modeling and local thermodynamic equilibrium radiative transfer calculations in order to shed light on the morpho-kinematic structure of its inner, wind-forming environment. Results. We detect 32 lines of 13 molecules and isotopologs (CO, SiO, SO, SO2, H2O, HCN, PN), including several transitions from vibrationally excited states. HCN, H13CN, and millimeter vibrationally excited H2O, SO, 34SO, SO2, and PN are detected for the first time in RS Cnc. Evidence for rotation is seen in HCN, SO, SO2, and SiO(v = 1). From CO and SiO channel maps, we find an inner, equatorial density enhancement, and a bipolar outflow structure with a mass-loss rate of 1 × 10−7 M⊙yr−1 for the equatorial region and of 2 × 10−7 M⊙yr−1 for the polar outflows. The 12CO/13CO ratio is measured to be ~20 on average, 24 ± 2 in the polar outflows and 19 ± 3 in the equatorial region. We do not find direct evidence of a companion that might explain this kind of kinematic structure, and explore the possibility that a magnetic field might be the cause of it. The innermost molecular gas is influenced by stellar pulsation and possibly by convective cells that leave their imprint on broad wings of certain molecular lines, such as SiO and SO. Conclusions. RS Cnc is one of the few nearby, low-mass-loss-rate, oxygen-rich AGB stars with a wind displaying both an equatorial disk and bipolar outflows. Its orientation with respect to the line of sight is particularly favorable for a reliable study of its morpho-kinematics. Nevertheless, the mechanism causing early spherical symmetry breaking remains uncertain, calling for additional high spatial- and spectral-resolution observations of the emission of different molecules in different transitions, along with more thorough investigation of the coupling among the different physical processes at play.

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The nascent wind of AGB star R doradus: evidence for a recent episode of enhanced mass loss

Cited by 8 publications

References 20 publications

Observation of High Doppler Velocity Wings in the Nascent Wind of R Doradus

Observation of High Doppler Velocity Wings in the Nascent Wind of R Doradus

On the origin of high Doppler velocity wings in the spectra of O-rich AGB stars

Molecules, shocks, and disk in the axi-symmetric wind of the MS-type AGB star RS Cancri

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