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LIBRIS Formathandbok  (Information om MARC21)
FältnamnIndikatorerMetadata
00005992naa a2200481 4500
001oai:research.chalmers.se:7bcd195c-11ce-452e-9a03-c0a6d2176251
003SwePub
008240515s2024 | |||||||||||000 ||eng|
0247 a https://research.chalmers.se/publication/5411312 URI
0247 a https://doi.org/10.1051/0004-6361/2023483822 DOI
040 a (SwePub)cth
041 a engb eng
042 9 SwePub
072 7a art2 swepub-publicationtype
072 7a ref2 swepub-contenttype
1001 a Khouri, Theo,d 1985u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)theok
2451 0a An empirical view of the extended atmosphere and inner envelope of the asymptotic giant branch star R Doradus I. Physical model based on CO lines
264 1c 2024
338 a electronic2 rdacarrier
520 a Context. The mass loss experienced on the asymptotic giant branch (AGB) at the end of the lives of low- and intermediate-mass stars is widely accepted to rely on radiation pressure acting on newly formed dust grains. Dust formation happens in the extended atmospheres of these stars, where the density, velocity, and temperature distributions are strongly affected by convection, stellar pulsation, and heating and cooling processes. The interaction between these processes and how that affects dust formation and growth is complex. Hence, characterising the extended atmospheres empirically is paramount to advance our understanding of the dust formation and wind-driving processes. Aims. We aim to determine the density, temperature, and velocity distributions of the gas in the extended atmosphere of the AGB star R Dor. Methods. We acquired observations using ALMA towards R Dor to study the gas through molecular line absorption and emission. We modelled the observed 12CO v = 0, J = 2−1, v = 1, J = 2−1, and 3−2 and 13CO v = 0, J = 3−2 lines using the 3D radiative transfer code LIME to determine the density, temperature, and velocity distributions up to a distance of four times the radius of the star at sub-millimetre wavelengths. Results. The high angular resolution of the sub-millimetre maps allows for even the stellar photosphere to be spatially resolved. By analysing the absorption against the star, we infer that the innermost layer in the near-side hemisphere is mostly falling towards the star, while gas in the layer above that seems to be mostly outflowing. Interestingly, the high angular resolution of the ALMA Band 7 observations reveal that the velocity field of the gas seen against the star is not homogenous across the stellar disc. The gas temperature and density distributions have to be very steep close to the star to fit the observed emission and absorption, but they become shallower for radii larger than ∼1.6 times the stellar sub-millimetre radius. While the gas mass in the innermost region is hundreds of times larger than the mass lost on average by R Dor per pulsation cycle, the gas densities just above this region are consistent with those expected based on the mass-loss rate and expansion velocity of the large-scale outflow. Our fits to the line profiles require the velocity distribution on the far side of the envelope to be mirrored, on average, with respect to that on the near side. Using a sharp absorption feature seen in the CO v = 0, J = 2−1 line, we constrained the standard deviation of the stochastic velocity distribution in the large-scale outflow to be .0.4 km s−1. We characterised two blobs detected in the CO v = 0, J = 2−1 line and found densities substantially larger than those of the surrounding gas. The two blobs also display expansion velocities that are high relative to that of the large-scale outflow. Monitoring the evolution of these blobs will lead to a better understanding of the role of these structures in the mass-loss process of R Dor.
650 7a NATURVETENSKAPx Geovetenskap och miljövetenskapx Meteorologi och atmosfärforskning0 (SwePub)105082 hsv//swe
650 7a NATURAL SCIENCESx Earth and Related Environmental Sciencesx Meteorology and Atmospheric Sciences0 (SwePub)105082 hsv//eng
650 7a NATURVETENSKAPx Fysikx Astronomi, astrofysik och kosmologi0 (SwePub)103052 hsv//swe
650 7a NATURAL SCIENCESx Physical Sciencesx Astronomy, Astrophysics and Cosmology0 (SwePub)103052 hsv//eng
653 a stars: AGB and post-AGB
653 a stars: mass-loss
653 a stars: imaging
653 a stars: winds, outflows
653 a circumstellar matter
653 a stars: individual: R Doradus
7001 a Olofsson, Hans,d 1952u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)hanolo
7001 a Vlemmings, Wouter,d 1974u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)wouterv
7001 a Schirmer, Thiébaut-Antoine,d 1992u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)thisch
7001 a Tafoya, Daniel,d 1981u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)tafoya
7001 a Maercker, Matthias,d 1979u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)maercker
7001 a De Beck, Elvire,d 1985u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)elvire
7001 a Nyman, Lars-Åke,d 1954u European Southern Observatory Santiago,Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)nymanla
7001 a Saberi, M.u Universitetet i Oslo,University of Oslo4 aut
7102 a Chalmers tekniska högskolab European Southern Observatory Santiago4 org
7730 t Astronomy and Astrophysicsg 685q 685x 0004-6361x 1432-0746
8564 u https://research.chalmers.se/publication/541131/file/541131_Fulltext.pdfx primaryx freey FULLTEXT
8564 8u https://research.chalmers.se/publication/541131
8564 8u https://doi.org/10.1051/0004-6361/202348382

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