ATOMIUM: ALMA tracing the origins of molecules in dust forming oxygen rich M-type stars Motivation, sample, calibration, and initial results
ATOMIUM: ALMA tracing the origins of molecules in dust forming oxygen rich M-type stars Motivation, sample, calibration, and initial results
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ATOMIUM：ALMA 追踪尘埃中形成富氧 M 型恒星的分子起源动机、样本、校准和初步结果
DOI：
10.1051/0004-6361/202140431
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发表时间：
2022
影响因子：
6.5
通讯作者：
Gottlieb C
中科院分区：
文献类型：
--
作者：
Gottlieb C
本文介绍了ATOMIUM，一个大型计划在第6周期与阿塔卡马大型毫米/亚毫米阵列（阿尔马）。ATOMIUM的目标是了解演化的渐近巨星分支（AGB）和红超巨星（RSG）风中的动力学和气相及尘埃形成化学。更普遍的目标是确定适用于其他天体物理环境的化学过程。十七富氧AGB和RSG星跨越（circum）恒星参数和演化阶段的范围内观察到的一个均匀的观测策略，允许一个明确的比较。在213.83和269.71 GHz之间以高（100 ″ .025-0″ .050）、中（100 ″ .13-0″ .24）和低（101 ″）角分辨率获得数据。每1.3 km s− 1通道的灵敏度为1.5-5 mJy beam−1，无谱线通道用于毫米波连续谱成像。我们研究气体动力学和尘埃形成的主要分子是CO，SiO，AlO，AlOH，TiO，TiO 2和HCN;次要分子包括SO，SO 2，SiS，CS，H2O和NaCl。科学的动机，调查设计，样本属性，数据减少，并概述了数据产品。此外，我们强调一个科学的结果-风运动的原子源。我们的分析表明，ATOMIUM源通常有一个缓慢的风加速度，和一小部分的气体达到的速度，可以高达两倍以上的因素比以前报道的终端速度假设各向同性膨胀。此外，风的运动学廓线建立的径向速度的动量方程描述的球形风结构不能捕捉速度场的复杂性。在15个源中，除了12 COv = 0 J = 2 − 1之外，一些分子跃迁达到了更高的流出速度，空间发射区通常大于30个恒星半径，但远小于CO的范围。 因此，ATOMIUM的数据提供了一个重要的基准，在单和双星星模型的演化恒星的风动力学。
This overview paper presents ATOMIUM, a Large Programme in Cycle 6 with the Atacama Large Millimeter/submillimeter Array (ALMA). The goal of ATOMIUM is to understand the dynamics and the gas phase and dust formation chemistry in the winds of evolved asymptotic giant branch (AGB) and red supergiant (RSG) stars. A more general aim is to identify chemical processes applicable to other astrophysical environments. Seventeen oxygen-rich AGB and RSG stars spanning a range in (circum)stellar parameters and evolutionary phases were observed in a homogeneous observing strategy allowing for an unambiguous comparison. Data were obtained between 213.83 and 269.71 GHz at high (∼0″.025–0″.050), medium (∼0″.13–0″.24), and low (∼1″) angular resolution. The sensitivity per ∼1.3 km s−1channel was 1.5–5 mJy beam−1, and the line-free channels were used to image the millimetre wave continuum. Our primary molecules for studying the gas dynamics and dust formation are CO, SiO, AlO, AlOH, TiO, TiO2, and HCN; secondary molecules include SO, SO2, SiS, CS, H2O, and NaCl. The scientific motivation, survey design, sample properties, data reduction, and an overview of the data products are described. In addition, we highlight one scientific result – the wind kinematics of the ATOMIUM sources. Our analysis suggests that the ATOMIUM sources often have a slow wind acceleration, and a fraction of the gas reaches a velocity which can be up to a factor of two times larger than previously reported terminal velocities assuming isotropic expansion. Moreover, the wind kinematic profiles establish that the radial velocity described by the momentum equation for a spherical wind structure cannot capture the complexity of the velocity field. In fifteen sources, some molecular transitions other than12COv= 0J= 2 − 1 reach a higher outflow velocity, with a spatial emission zone that is often greater than 30 stellar radii, but much less than the extent of CO. We propose that a binary interaction with a (sub)stellar companion may (partly) explain the non-monotonic behaviour of the projected velocity field. The ATOMIUM data hence provide a crucial benchmark for the wind dynamics of evolved stars in single and binary star models.