Extragalactic Planetary Nebulae

河外行星状星云

• 批准号: 0807522
• 负责人: Roberto Mendez
• 金额: $ 33.83万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0807522&HistoricalAwards=false
• 关键词: Extragalactic; Planetary; Nebulae

Under this renewal of AST-0307489, Dr. Mendez will use a technique of narrowband imaging and slitless spectroscopy on 8-meter telescopes to find planetary nebulae in the outskirts of elliptical and S0 galaxies, and measure their radial velocities. Planetary nebulae represent the final stages in the life of a star like our Sun. They are identified by the bright emission lines of gas ionized by the hot exposed stellar core; these lines are also used to measure motion along the line of sight. The distribution and motion of the planetary nebulae will be used to study the galaxy's gravitational field, and hence its dark matter content. Dr Mendez will also use the brightness ratio of emission from hydrogen atoms with that from oxygen, to estimate how the chemical composition of the gas from which the stars were formed depends on distance from the galaxy center. Dr. Mendez and the Munich group with which he collaborates have already studied several galaxies; some show no evidence for dark matter, while others have clear signatures of its presence. Under the present proposal, the next target is M60, a flattened galaxy with a halo of hot X-ray gas that provides an alternative measure of the mass of the galaxy's dark halo. Other target galaxies will be selected to cover a range in luminosity, and to coordinate with another project using the 4-meter Herschel telescope on La Palma (Canary Islands, Spain), which can detect only the brightest planetary nebulae. A graduate student and an undergraduate will be trained through their involvement in the research. Dr Mendez will develop a website explaining the project that will be accessible to the general public or students in elementary survey courses; it will cover topics ranging from the nature of light to evidence for dark matter around galaxies.

根据AST-0307489的这种续签，门德斯博士将在8米望远镜上使用窄带成像和无狭窄光谱的技术，以在椭圆形和S0星系郊外找到行星星云，并测量其径向速度。 行星星云代表着像我们的太阳一样的恒星生活中的最后阶段。 它们是通过热裸露的恒星芯电离气体的明亮发射线来识别的。这些线也用于测量沿视线的运动。 行星星云的分布和运动将用于研究星系的重力场，从而将其暗物质含量。门德斯博士还将利用氢原子与氧气的发射比的亮度比，以估计形成恒星的气体的化学成分如何取决于距离星系中心的距离。 Mendez博士和他合作的慕尼黑集团已经研究了几个星系。一些人没有证据表明暗物质，而另一些则有明确的签名。 根据本提案，下一个目标是M60，它是一个扁平的星系，带有热X​​射线气体的光环，提供了对银河系深光晕质量的替代度量。将选择其他目标星系来覆盖光度的范围，并使用La Palma（西班牙金丝雀群岛）上的4米赫歇尔望远镜与另一个项目进行协调，该项目只能检测到最亮的行星星云。 研究生和本科生将通过参与研究而接受培训。 门德斯博士将开发一个网站，解释该项目，该项目将在公众或基础调查课程中可以访问；它将涵盖从光的性质到星系中暗物质的证据的主题。