2019MNRAS.487..622T

Using ALMA observations of ¹²CO(2-1), ²⁸SiO(5-4), and ³²SO₂(16_6,10-17_5,13) emissions of the circumstellar envelope of AGB star EP Aqr, we describe the morpho-kinematics governing the nascent wind. Main results are as follows: (1) Two narrow polar structures, referred to as jets, launched from less than 25 au away from the star, build up between ∼20 and ∼100 au to a velocity of ∼20 km s^–1. They fade away at larger distances and are barely visible in CO data. (2) SO₂, SiO, and CO emissions explore radial ranges reaching, respectively, ∼30, 250, and 1000 au from the star, preventing the jets to be detected in SO₂ data. (3) Close to the star photosphere, rotation (undetected in SiO and CO data) and isotropic radial expansion combine with probable turbulence to produce a broad SO₂ line profile (∼7.5 km s^–1 full width at half-maximum). (4) A same axis serves as axis of rotation close to the star, as jet axis and as axi-symmetry axis at large distances. (5) A radial wind builds up at distances up to ∼300 au from the star, with larger velocity near polar than equatorial latitudes. (6) A sharp depletion of SiO and CO emissions, starting near the star, rapidly broadens to cover the whole blue-western quadrant, introducing important asymmetry in the CO and particularly SiO observations. (7) The ¹²C/¹³C abundance ratio is measured as 9 ± 2. (8) Plausible interpretations are discussed, in particular assuming the presence of a companion.