论文标题
快速发展的AGB星V Hya：Alma找到了一个具有高速流出的多环马戏团
The Rapidly Evolving AGB Star, V Hya: ALMA finds a Multi-Ring Circus with High-Velocity Outflows
论文作者
论文摘要
我们已经观察到了质量失去的碳恒星V Hya，显然正在以〜0“ .4-0” .6的前所未有的角度分辨率（用Atacama大毫米/毫米/亚毫米波阵列（Alma）过渡为〜0“ .4-0” .6。我们的13CO和12CO（j = 3-2和j = 2-1）图像导致在系统的赤道平面中发现了动态扩展（Dude）的张开，翘曲的磁盘结构（花花公子）内的六个六个膨胀环。我们还第一次发现了几个双极，高速流出的流出，其中一些具有抛物线形态，这意味着宽开头角度，而一个（以前发现）是块状且高度简单的。后者可能与V hya电离气体的高速子弹样弹出有关；在12CO图像中可以看到4个子弹中最古老的分子对应物。我们发现连续发射的明亮，未解决的中心来源（FWHM大小<〜165 au）；大约40％的发射可以在标准的无线电光球中产生，而其余的60％可能是由于非常大的（mm尺寸）晶粒的热发射，质量> 〜10^{-5} msun。我们已经使用了辐射转移模型来适合花花公子的13co和12co排放的显着特性，达到8英寸（3200 au）的半径，尺寸为1.7 x 10^{ - 3} msun，其膨胀速度的扩张速度随着半径的增长而增加，在200 au sup的中心范围内，其速度很快就会增加，然后从9.5 km/sue sive i shem and shere/s sy shere/s s i s s i gy 5 km/se s s s i y 5 d km。潜在的密度降低了径向降低，并散布着局部增加，代表了观察到的最内部的三个环。
We have observed the mass-losing carbon star V Hya that is apparently transitioning from an AGB star to a bipolar planetary nebula, at an unprecedented angular resolution of ~0".4-0".6 with the Atacama Large Millimeter/submillimeter Wave Array (ALMA). Our 13CO and 12CO (J=3-2 and J=2-1) images have led to the discovery of a remarkable set of six expanding rings within a flared, warped Disk structure Undergoing Dynamical Expansion (DUDE) that lies in the system's equatorial plane. We also find, for the first time, several bipolar, high-velocity outflows, some of which have parabolic morphologies, implying wide opening angles, while one (found previously) is clumpy and highly collimated. The latter is likely associated with the high-velocity bullet-like ejections of ionized gas from V Hya; a possible molecular counterpart to the oldest of the 4 bullets can be seen in the 12CO images. We find a bright, unresolved central source of continuum emission (FWHM size <~165 au); about 40% of this emission can be produced in a standard radio photosphere, while the remaining 60% is likely due to thermal emission from very large (mm-sized) grains, having mass >~10^{-5} Msun. We have used a radiative transfer model to fit the salient characteristics of the DUDE's 13CO and 12CO emission out to a radius of 8" (3200 au) with a flared disk of mass 1.7 x 10^{-3} Msun, whose expansion velocity increases increases very rapidly with radius inside a central region of size ~200 au, and then more slowly outside it, from 9.5 to 11.5 km/s. The DUDE's underlying density decreases radially, interspersed with local increases that represent the observationally well-characterised innermost three rings.
