Linking Galactic and Extragalactic Star Formation

连接银河系和河外恒星的形成

• 批准号: 1516021
• 负责人: Loren Anderson
• 金额: $ 36.37万
• 依托单位: West Virginia University Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1516021&HistoricalAwards=false
• 关键词: Linking; Galactic; Extragalactic; Star; Formation

It is surprising how little we know about global star formation in our Milky Way Galaxy compared to other galaxies in the Universe. This is because the Sun lies in the flat Milky Way disk and because nearly all star formation occurs within this disk. Looking at the sky, the disk appears as a relatively thin band, with stars at all distances found within this band. This project will disentangle this band of light into a three-dimensional map with the aim of understanding the global star formation in our Galaxy. This map will allow us to differentiate between the brightness of regions (an observed property) with their luminosities (an intrinsic property). The team will create the three-dimensional map by measuring the brightness of all known massive star formation regions at infrared and radio wavelengths, and will use radio observations to turn the infrared and radio brightnesses into luminosities. Local high school students will assist in the observations, providing vital research opportunities for the students of West Virginia. The PI and his students will compare the distribution of derived luminosities with that of other galaxies to determine the type of galaxy we live in. They will also estimate how many stars our Galaxy is forming. These results will help us to better understand star formation in our Galactic home.There is a severe lack of communication between Galactic and extragalactic astronomers because there is no complete sample of Galactic star forming regions that can be compared to those of external galaxies. The team will solve this problem by creating a catalog of all Galactic HII regions ionized by single O-stars using radio recombination line observations. Local high school students will help with the observations, providing vital science opportunities for the students of West Virginia. These observations will allow us to compute kinematic distances from the observed radial velocities using a rotation curve model. The team will supplement the distances by locating clusters of HII regions that have similar radial velocities, and presumably similar distances, and will adjust for catalog biases using a population synthesis model. The PI and his students will derive HII region fluxes at wavelengths from 8 micron to 21 cm and turn these fluxes into luminosities using the catalog distances. They will investigate three extragalactic results found in studies of the HII region luminosity function (LF): the break in the Galactic LF seen in some galaxies, the finding that ''clustered'' and ''distributed'' HII-region LFs have different shapes, and the correlation between the galaxy's LF shape and its Hubble type. The total Milky Way luminosity can then be computed by summing the luminosities of all catalog HII regions. The total Milky Way luminosities will then be converted into star formation rates using extragalactic star formation rate calibrations.

令人惊讶的是，与宇宙中的其他星系相比，我们对银河系中全球恒星形成的了解很少。这是因为太阳位于平坦的银河系磁盘上，并且几乎全明星地层发生在此磁盘中。看着天空，磁盘显示为一个相对较薄的带，在该乐队中都有各个距离的星星。该项目将将这一光乐队置于三维图中，以了解我们银河系中的全球恒星形成。该地图将使我们能够区分区域的亮度（观察到的特性），其亮度（一种内在特性）。该团队将通过测量红外和无线电波长的所有已知巨星形成区域的亮度来创建三维地图，并将使用无线电观测来将红外线和无线电亮度转变为亮度。当地的高中生将协助观察，为西弗吉尼亚州的学生提供重要的研究机会。 PI和他的学生将比较派生的亮度的分布与其他星系的分布，以确定我们居住的星系类型。他们还将估计我们的星系形成了多少恒星。这些结果将有助于我们更好地了解银河系中的恒星形成。由于没有完整的银河系恒星形成区域样本可以将其与外部星系进行比较，因此银河系和层状天文学家之间存在严重缺乏通信。该团队将使用无线电重组线观测值创建一个由单个O-Stars电离的所有银河HII区域的目录来解决此问题。当地的高中生将帮助进行观察，为西弗吉尼亚州的学生提供重要的科学机会。这些观察结果将使我们能够使用旋转曲线模型来计算观察到的径向速度的运动学距离。该团队将通过定位具有相似径向速度和相似距离的HII区域的簇来补充距离，并使用种群合成模型来调整目录偏差。 PI和他的学生将以从8微米到21厘米的波长得出HII区域通量，并使用目录距离将这些通量转化为亮度。他们将研究在HII区域光度函数（LF）的研究中发现的三个外乳术结果：在某些星系中看到的银河LF的破裂，发现“簇”和“分布”的Hii-Region LFS具有不同的形状，以及银河系的LF形状和其臀部的相关性。然后，可以通过求和所有目录HII区域的亮度来计算总银河系亮度。然后，使用外层状恒星形成速率校准将亮度的总银值转换为恒星形成速率。

项目成果

FINDING DISTANT GALACTIC H ii REGIONS

• DOI: 10.1088/0067-0049/221/2/26
• 发表时间: 2015-10
• 期刊: The Astrophysical Journal Supplement Series
• 作者: L. Anderson;W. Armentrout;B. Johnstone;T. Bania;D. Balser;T. Wenger;V. Cunningham