The dust enrichment of galaxies: supernovae and evolved stars

超新星在天体物理学中占有举足轻重的地位，不仅是因为它们作为标准蜡烛和宇宙学探测器的重要性，还因为它们在决定星系的整体能量、质量循环率和重元素丰度方面发挥着主要作用。有人假设，超新星(SNE)可能是宇宙中尘埃粒子的主要来源，甚至是主要来源。间接支持这一假设的事实是，已知的许多最早形成的星系都是极其尘埃和红外线发光的，这一事实从Scuba和其他仪器有效地探测到它们在亚毫米波长的红移尘埃发射中得到了证明。似乎只有大质量恒星才能在短时间内产生观测到的尘埃，要么是在SN事件之前的尘埃质量损失阶段，要么是在SN事件的膨胀和冷却喷射物中。尘埃形成模型证实，SN喷出物中新形成的尘埃应该在爆发后1-2年内在中红外波长上变得可探测到，并且中IR特别适合于追踪SNE中尘埃形成的开始和确定形成的尘埃量。随着配备了灵敏中红外仪器的地面8米望远镜的出现，如双子座的Michelle和TReCS，以及斯皮策太空望远镜(SST)的发射，已经有了足够的灵敏度来开始搜索附近星系中超新星的中红外辐射。由来自北美和欧洲的天文学家组成的我们的SEED合作(超新星尘埃河外发射调查)获得了SST时间，使用IRAC和MIPS仪器搜索附近超新星爆发数百天后发出的中红外尘埃。此外，我们还获取了一些附近星系的SINS Legacy SST数据，这些星系是用相同的仪器获得的，目的是寻找这些星系内最近SNE的中红外辐射。这项提议寻求持续的博士后资助，以便能够完成超新星尘埃项目。此外，欧空局2007年发射赫歇尔空间观测站后，将作为赫歇尔空间观测站保证时间观测的一部分，获得对演化恒星周围扩展尘埃壳的新的远红外和亚毫米测绘观测，目的是解决低质量和中等质量恒星的“丢失质量”问题。

Supernovae occupy a pivotal position in astrophysics, not only because of their importance as standard candles and cosmological probes but also because of the prime role that they play in determining the overall energetics, mass recycling rate and heavy-element enrichment of galaxies. It has been hypothesised that supernovae (SNe) may be a major, or even dominant, source of dust particles in the Universe. Indirect support for this supposition comes from the fact that many of the earliest-formed galaxies known are extremely dusty and IR-luminous, as evidenced by the efficient detection of their redshifted dust emission at submillimetre wavelengths by SCUBA and other instruments. It seems that only massive stars can have produced the observed dust over the short timescales implied, either during during dusty mass-losing phases prior to the SN event or else within the expanding and cooling ejecta from the SN event. Dust formation models confirm that newly formed dust in SN ejecta should become detectable at mid-IR wavelengths within 1-2 years of outburst and that the mid-IR is particularly suitable to trace the onset of dust formation in SNe and to determine the amount of dust formed. With the advent of ground-based 8-m telescopes equipped with sensitive mid-IR instruments, such as Gemini's Michelle and TReCS, and the launch of the Spitzer Space Telescope (SST), sufficient sensitivity has become available to embark on searches for mid-IR emission from supernovae in nearby galaxies. Our SEEDS collaboration (Survey for Extragalactic Emission from Dust in Supernovae), composed of astronomers from North America and Europe, has obtained SST time to search for mid-IR dust emission from nearby supernovae hundreds of days after their outbursts, using the IRAC and MIPS instruments. In addition, we have accessed SINGS Legacy SST data on a number of nearby galaxies that have been obtained with the same instruments, in order to search for mid-IR emission from recent SNe within these galaxies. This proposal seeks continued postdoctoral funding in order to allow completion of the supernova dust project. In addition, new far-infrared and submillimetre mapping observations of extended dust shells around evolved stars will be obtained as part of Herschel Space Observatory Guaranteed Time observations following its launch by ESA in 2007, with the aim of addressing the `missing mass' problem for low and intermediate mass stars.