An Observational Investigation of Mass Loss in Evolved Stars Using Millimeter Interferometry and Mid-IR Wavelength Imaging

使用毫米干涉测量和中红外波长成像对演化恒星的质量损失进行观测研究

• 批准号: 9521605
• 负责人: Margaret Meixner
• 金额: $ 2万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-05-01 至 1997-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9521605&HistoricalAwards=false
• 关键词: Observational; Investigation; Mass; Loss; Evolved

9521605 Meixner Mass loss has a profound effect on the final evolution of intermediate mass stars. Unfortunately, the physical mechanism driving the extreme mass loss rates on the asymptotic giant branch (AGB) is not understood. Dr. Margaret Meixner of the University of Illinois, Urbana-Champaign, will conduct an observational investigation of the nature of the mass loss in evolved stars using imaging techniques in two wavebands: millimeter wavelength (3 mm), and mid-IR wavelength (8-25 microns). The carbon monoxide emission millimeter wavelength (transition J=1-0) imaging project utilizes the Berkeley-Illinois-Maryland millimeter wavelength array (BIMA) and the NRAO 12m telescope for observations, and a detailed radiative transfer software code for the analysis of the data. The expected results will include more accurate determination of mass loss rates and characterization of the large scale halos (radii about 70 arc seconds) which are found in all evolved stars; and compact (less than 4 arc seconds) fast molecular gas regions, which are found in transition objects such as proto-planetary nebulae (PPNe) and hold a clue to the AGB to planetary nebula (Pne) transition process. The mid-IR wavelength imaging project involves the analysis of high resolution (less than 1 arc second) mid-IR wavelength images of 55 circumstellar dust shells (CDSs) surrounding AGB stars, PPNe and young Pne, will be carried out using an axially symmetric radiative transfer dust code. Moreover, the mid-IR wavelength project includes further observations of PPNe and extreme AGB stars at similar and longer wavelengths and at high angular resolutions (about 0.1 arc seconds) using two mid-IR wavelength array cameras (MIRAC and the Keck LWIRC). The results from this mid-IR wavelength imaging project will provide insight into the origin of axially symmetric morphological structures commonly found in Pne and insight into the evolutionary stage at which this axial symmetry arises. Dr. Me ixner has three activities planned that will lay ground work for the future research. Firstly, an observing run is planned with the MIRAC team in June 1995 to observe approximately one dozen PPNe. Secondly, a new axially symmetric computer software dust code will be used to model several mid-IR images of PPNe and Pne from the current sample; thereby demonstrating the application of this code. Finally, carbon monoxide wavelength emission data cubes of three objects will be constructed using a new interferometry technique called mosaicing; thereby demonstrating the feasibility of this technique.

9521605 Meixner 质量损失对中等质量恒星的最终演化有着深远的影响。 不幸的是，驱动渐近巨星分支（AGB）极端质量损失率的物理机制尚不清楚。 伊利诺伊大学厄巴纳-香槟分校的玛格丽特·梅克斯纳 (Margaret Meixner) 博士将使用两个波段的成像技术对演化恒星质量损失的性质进行观测研究：毫米波长 (3 mm) 和中红外波长 (8 -25微米）。 一氧化碳排放毫米波长（跃迁J=1-0）成像项目利用伯克利-伊利诺伊-马里兰毫米波长阵列（BIMA）和NRAO 12m望远镜进行观测，并使用详细的辐射传输软件代码来分析数据。 预期结果将包括更准确地确定质量损失率以及所有演化恒星中发现的大尺度晕（半径约为 70 角秒）的特征；致密（小于 4 角秒）快速分子气体区域，这些区域存在于原行星状星云 (PPNe) 等过渡物体中，并为 AGB 到行星状星云 (Pne) 过渡过程提供了线索。 中红外波长成像项目涉及对 AGB 恒星、PPNe 和年轻 Pne 周围 55 个星周尘埃壳 (CDS) 的高分辨率（小于 1 角秒）中红外波长图像进行分析，将使用轴对称辐射传输尘埃代码。 此外，中红外波长项目包括使用两台中红外波长阵列相机（MIRAC 和 Keck LWIRC）以相似和更长的波长以及高角分辨率（约 0.1 角秒）对 PPNe 和极端 AGB 恒星进行进一步观测。 这个中红外波长成像项目的结果将有助于深入了解 Pne 中常见的轴对称形态结构的起源，并深入了解这种轴对称性出现的进化阶段。 Me ixner 博士计划了三项活动，为未来的研究奠定基础。 首先，计划于 1995 年 6 月与 MIRAC 团队进行一次观测运行，观测大约 12 个 PPNe。 其次，将使用新的轴对称计算机软件灰尘代码对当前样本中的 PPNe 和 Pne 的几幅中红外图像进行建模；从而演示了该代码的应用。 最后，将使用一种称为马赛克的新干涉测量技术构建三个物体的一氧化碳波长发射数据立方体； 从而证明该技术的可行性。