Observational and Laboratory Studies of the Evolution of Circumstellar Material

星周物质演化的观测和实验室研究

• 批准号: 2307305
• 负责人: Lucy Ziurys
• 金额: $ 39.6万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307305&HistoricalAwards=false
• 关键词: Observational; Laboratory; Studies; Evolution; Circumstellar

Mass loss from circumstellar envelopes in the late stages of stellar evolution is a major avenue by which the interstellar medium (ISM) becomes enriched in gas, dust, and heavy elements. This research project will investigate the gas phase molecular content of stellar ejecta, from asymptotic giant branch (AGB) stars to protoplanetary nebule (PPNe) and planetary nebulae (PNe). The investigators will extend their ongoing program of radio astronomical observations and laboratory measurements to characterize the molecular inventory and physical properties of these objects. Results from the project will allow astronomers to understand the nature of stellar ejecta and their influence on the diffuse ISM. The project will train graduate and undergraduate students in advanced techniques of radio astronomy and laboratory astrophysics.This research program seeks to elucidate how molecular material evolves from the AGB phase, through the intermediate PPNe phase, to the advanced PNe phase. To accomplish this, the investigators will undertake: (1) a better assessment of the carbon budget and isotope ratios through an extensive analysis of a highly sensitive broadband millimeter-wave survey of the carbon-rich envelope of the AGB star IRC+10216; (2) laboratory measurements of the rotational spectra of new metal-bearing carbides in the radio band to aid their identification in circumstellar envelopes; (3) an analysis of high spatial resolution images of the oxygen-rich envelope of VY Canis Majoris in a variety of molecules to understand the influence of the C/O ratio; and (4) evaluation of the molecular and isotopic composition of a diverse sample of carbon-rich and oxygen-rich PPNe and PNe by radio astronomical observations. A better understanding of the nature of the stellar ejecta, particularly PNe, would also advance our understanding of how they enrich the diffuse ISM.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在恒星演化的后期，来自星周包层的质量损失是星际介质(ISM)变得富含气体、尘埃和重元素的主要途径。这项研究项目将研究从渐近巨星分支(AGB)恒星到原行星状星云(PPNe)和行星状星云(PNE)的恒星喷出物的气相分子含量。研究人员将扩展他们正在进行的射电天文观测和实验室测量计划，以表征这些天体的分子清单和物理性质。该项目的结果将使天文学家了解恒星喷发的性质及其对扩散的ISM的影响。该项目将对研究生和本科生进行射电天文学和实验室天体物理学高级技术方面的培训。这项研究计划旨在阐明分子材料如何从AGB阶段，通过PPNe中级阶段，进化到高级PNE阶段。为此，研究人员将进行：(1)通过对AGB恒星IRC+10216富碳包层的高灵敏度宽带毫米波测量的广泛分析，更好地评估碳收支和同位素比率；(2)实验室测量射电频带中新的含金属碳化物的转动光谱，以帮助在星周包层中识别它们；(3)分析VY Canis Majoris在各种分子中富氧包层的高空间分辨率图像，以了解C/O比的影响；以及(4)通过射电天文观测评估各种富碳和富氧的PPNe和PNE的分子和同位素组成。更好地了解恒星喷发的性质，特别是PNE，也将促进我们对它们如何丰富弥漫的ISM的理解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。