残盘与原行星盘的红外辐射研究
发布时间：2018-11-13 11:13
【摘要】：星周盘在早期恒星演化与行星形成过程中起着非常重要的作用。红外辐射是探索星周盘最有效的方法之一。AKARI/FIS亮源数据库(AKARIBSC)是一个无偏的全天巡天AKARI的涵盖65到160微米的远红外点源数据库,为寻找星周盘提供了独特的数据库。本论文详细介绍了作者在博士期间利用AKARIBSC去寻找残盘与原行星盘的两项工作。 第一项工作主要讲述AKARI/FIS探测到的亮残盘候选体。我们用Hipparcos的主序星数据库匹配AKARIBSC,证认了至少一个远红外波段探测的源共136个,匹配的可靠性大于90%。在排除了57个污染源或者是其它红外超的源比如YSO、Be星等,和4个没有红外超的源后,一共得到了75个残盘候选体。我们的样本源光谱型分布从B型到K型,早型的占主导。这是目前为止用全天巡天数据寻找到的唯一一个很亮的残盘候选体样本,巡天的空间分辨率比前一个全天样本所用巡天IRAS高出8倍多。再者,通过搜集其它公布的红外测光数据,样本中约四分之三的源具有多于一个波段的红外超辐射,从而可以估计尘埃的温度。我们用黑体模型去拟合这些源的SED,得到盘的参数及其统计分布。其中4个B型星具有4个及以上的波段红外超辐射,我们用双温的黑体模型拟合得到它们的温度,高温在200K或者100K,低温在50K或者40K。 第二项工作是关于我们寻找AKARI/FIS中的长寿命原初行星盘。基于他人做的AKARI/FIS的年轻恒星体样本,我们通过匹配Hipparcos的数据库共计得到25个源,匹配可靠性大于为90%。在排除了行星状星云和红巨星等4个源后得到太阳系附近的21个年轻恒星体,恒星的光谱类型分布从B型到M型星。利用Hipparcos精确的三角视差测量,定出源在赫罗图的位置分布,进而与理论的演化轨迹等时线比较估算恒星的年龄。结果发现样本中存在2个年龄大于10Myr的年轻恒星体。再者,通过搜集中红外WISE的数据,构建这2个源的光学至红外能谱分布,发现这2个源是II型年轻恒星体,即有原初行星盘。换而言之,我们在AKARI/FIS的年轻恒星体样本中共找到了2个长寿命原行星盘。利用Liu的理论模型对这两个源做能谱拟合,得到了中心星的光度和有效温度,继而利用Siess的前主序演化轨迹得出这两个源的年龄分别为14.1±4.2Myr和16.8±4.4Myr。长寿命原行星盘的存在对行星及其宿主恒星的形成有重要影响。
[Abstract]:The circumstellar disk plays a very important role in the early stellar evolution and planetary formation. Infrared radiation is one of the most effective methods to explore the circumstellar disk. The AKARI/FIS bright source database (AKARIBSC) is an unbiased far infrared point source database covering 65 to 160 microns of the all Sky Survey AKARI, which provides a unique database for searching for the circumstellar disk. This paper describes in detail the author's work of using AKARIBSC to search for the remnant disk and the original planetary disk during his PhD. The first work focuses on bright disk candidates detected by AKARI/FIS. We have identified 136 sources of at least one far-infrared band detection using Hipparcos's principal sequence star database matching AKARIBSC, and the matching reliability is greater than 90. After excluding 57 sources of pollution or other sources of infrared superposition such as YSO,Be magnitude, and 4 sources without infrared superposition, a total of 75 residual disk candidates were obtained. Our sample source spectral distribution ranges from type B to type K, with the early type dominating. So far, this is the only bright residual disk candidate sample to be found with the all-day survey data. The spatial resolution of the survey is more than eight times higher than that of the survey IRAS used in the previous full-day survey. Furthermore, by collecting other published infrared photometric data, about 3/4 of the sources in the sample have more than one band of infrared superradiance, thus allowing the temperature of dust to be estimated. We use the blackbody model to fit the SED, of these sources to obtain the disk parameters and their statistical distribution. Four of the B-type stars have four or more bands of infrared superradiance. The temperature of these stars is estimated by using a two-temperature blackbody model. The temperature is 200K or 100K at high temperature and 50K or 40K at low temperature. The second job is for us to look for long-lived primordial planetary disks in AKARI/FIS. Based on the young star body samples of AKARI/FIS made by others, we obtained a total of 25 sources by matching the database of Hipparcos, and the matching reliability was greater than 90. After excluding 4 sources such as planetary nebula and red giant, 21 young star bodies near the solar system were obtained. The spectral types of stars ranged from type B to type M. The location distribution of the source in the Hero diagram is determined by using the Hipparcos precise triangular parallax measurement, and the age of the star is estimated compared with the theoretical evolution trajectory isochron. It was found that there were two young star bodies older than 10Myr in the sample. Furthermore, by collecting the data of mid-infrared WISE, the optical to infrared spectrum distribution of these two sources is constructed. It is found that these two sources are II type young star bodies, that is, the primordial planetary disk. In other words, we found two long-lived protoplanetary disks in AKARI/FIS 's sample of young stars. The luminosity and effective temperature of the central star are obtained by using the theoretical model of Liu. The ages of the two sources are 14.1 卤4.2Myr and 16.8 卤4.4 Myr, respectively. The existence of long-lived protoplanetary disk has an important influence on the formation of planets and their host stars.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P141.91
本文编号：2328941
[Abstract]:The circumstellar disk plays a very important role in the early stellar evolution and planetary formation. Infrared radiation is one of the most effective methods to explore the circumstellar disk. The AKARI/FIS bright source database (AKARIBSC) is an unbiased far infrared point source database covering 65 to 160 microns of the all Sky Survey AKARI, which provides a unique database for searching for the circumstellar disk. This paper describes in detail the author's work of using AKARIBSC to search for the remnant disk and the original planetary disk during his PhD. The first work focuses on bright disk candidates detected by AKARI/FIS. We have identified 136 sources of at least one far-infrared band detection using Hipparcos's principal sequence star database matching AKARIBSC, and the matching reliability is greater than 90. After excluding 57 sources of pollution or other sources of infrared superposition such as YSO,Be magnitude, and 4 sources without infrared superposition, a total of 75 residual disk candidates were obtained. Our sample source spectral distribution ranges from type B to type K, with the early type dominating. So far, this is the only bright residual disk candidate sample to be found with the all-day survey data. The spatial resolution of the survey is more than eight times higher than that of the survey IRAS used in the previous full-day survey. Furthermore, by collecting other published infrared photometric data, about 3/4 of the sources in the sample have more than one band of infrared superradiance, thus allowing the temperature of dust to be estimated. We use the blackbody model to fit the SED, of these sources to obtain the disk parameters and their statistical distribution. Four of the B-type stars have four or more bands of infrared superradiance. The temperature of these stars is estimated by using a two-temperature blackbody model. The temperature is 200K or 100K at high temperature and 50K or 40K at low temperature. The second job is for us to look for long-lived primordial planetary disks in AKARI/FIS. Based on the young star body samples of AKARI/FIS made by others, we obtained a total of 25 sources by matching the database of Hipparcos, and the matching reliability was greater than 90. After excluding 4 sources such as planetary nebula and red giant, 21 young star bodies near the solar system were obtained. The spectral types of stars ranged from type B to type M. The location distribution of the source in the Hero diagram is determined by using the Hipparcos precise triangular parallax measurement, and the age of the star is estimated compared with the theoretical evolution trajectory isochron. It was found that there were two young star bodies older than 10Myr in the sample. Furthermore, by collecting the data of mid-infrared WISE, the optical to infrared spectrum distribution of these two sources is constructed. It is found that these two sources are II type young star bodies, that is, the primordial planetary disk. In other words, we found two long-lived protoplanetary disks in AKARI/FIS 's sample of young stars. The luminosity and effective temperature of the central star are obtained by using the theoretical model of Liu. The ages of the two sources are 14.1 卤4.2Myr and 16.8 卤4.4 Myr, respectively. The existence of long-lived protoplanetary disk has an important influence on the formation of planets and their host stars.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P141.91
【共引文献】
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4 宁长春;张辉杰;;大质量恒星形成区中CO分子外向流的观测和研究[J];西藏大学学报(自然科学版);2013年02期
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