Volume 614, June 2018
|Number of page(s)||10|
|Section||Interstellar and circumstellar matter|
|Published online||22 June 2018|
ALMA detection of a tentative nearly edge-on rotating disk around the nearby AGB star R Doradus
Institute of Astronomy, KU Leuven,
Celestijnenlaan 200D B2401,
2 Sterrenkundig Instituut “Anton Pannekoek”, Science Park 904, 1098 XH Amsterdam, The Netherlands
3 NASA Goddard Space Flight Center, Code 690, Greenbelt, MD 20771, USA
Accepted: 14 March 2018
A spectral scan of the circumstellar environment of the asymptotic giant branch (AGB) star R Doradus was taken with ALMA in cycle 2 at frequencies between 335 and 362 GHz and with a spatial resolution of ~150 milliarcseconds. Many molecular lines show a spatial offset between the blue and red shifted emission in the innermost regions of the wind. The position-velocity diagrams of this feature, in combination with previous SPHERE data and theoretical work point towards the presence of a compact differentially rotating disk, orientated nearly edge-on. We model the 28SiO (v = 1, J = 8 → 7) emission with a disk model. We estimate the disk mass and angular momentum to be 3 × 10−6 M⊙ and 5 × 1040 m2 kg s−1. The latter presents an “angular momentum problem” that may be solved by assuming that the disk is the result of wind-companion interactions with a companion of at least 2.5 earth masses, located at 6 AU, the tentatively determined location of the disk’s inner rim. An isolated clump of emission is detected to the south-east with a velocity that is high compared to the previously determined terminal velocity of the wind. Its position and mean velocity suggest that it may be associated with a companion planet, located at the disk’s inner rim.
Key words: radiative transfer / stars: AGB and post-AGB / circumstellar matter / submillimeter: stars
© ESO 2018
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