殘盤與原行星盤的紅外輻射研究
發(fā)布時間：2018-11-13 11:13
【摘要】：星周盤在早期恒星演化與行星形成過程中起著非常重要的作用。紅外輻射是探索星周盤最有效的方法之一。AKARI/FIS亮源數(shù)據(jù)庫(AKARIBSC)是一個無偏的全天巡天AKARI的涵蓋65到160微米的遠(yuǎn)紅外點源數(shù)據(jù)庫,為尋找星周盤提供了獨(dú)特的數(shù)據(jù)庫。本論文詳細(xì)介紹了作者在博士期間利用AKARIBSC去尋找殘盤與原行星盤的兩項工作。 第一項工作主要講述AKARI/FIS探測到的亮殘盤候選體。我們用Hipparcos的主序星數(shù)據(jù)庫匹配AKARIBSC,證認(rèn)了至少一個遠(yuǎn)紅外波段探測的源共136個,匹配的可靠性大于90%。在排除了57個污染源或者是其它紅外超的源比如YSO、Be星等,和4個沒有紅外超的源后,一共得到了75個殘盤候選體。我們的樣本源光譜型分布從B型到K型,早型的占主導(dǎo)。這是目前為止用全天巡天數(shù)據(jù)尋找到的唯一一個很亮的殘盤候選體樣本,巡天的空間分辨率比前一個全天樣本所用巡天IRAS高出8倍多。再者,通過搜集其它公布的紅外測光數(shù)據(jù),樣本中約四分之三的源具有多于一個波段的紅外超輻射,從而可以估計塵埃的溫度。我們用黑體模型去擬合這些源的SED,得到盤的參數(shù)及其統(tǒng)計分布。其中4個B型星具有4個及以上的波段紅外超輻射,我們用雙溫的黑體模型擬合得到它們的溫度,高溫在200K或者100K,低溫在50K或者40K。 第二項工作是關(guān)于我們尋找AKARI/FIS中的長壽命原初行星盤�；谒俗龅腁KARI/FIS的年輕恒星體樣本,我們通過匹配Hipparcos的數(shù)據(jù)庫共計得到25個源,匹配可靠性大于為90%。在排除了行星狀星云和紅巨星等4個源后得到太陽系附近的21個年輕恒星體,恒星的光譜類型分布從B型到M型星。利用Hipparcos精確的三角視差測量,定出源在赫羅圖的位置分布,進(jìn)而與理論的演化軌跡等時線比較估算恒星的年齡。結(jié)果發(fā)現(xiàn)樣本中存在2個年齡大于10Myr的年輕恒星體。再者,通過搜集中紅外WISE的數(shù)據(jù),構(gòu)建這2個源的光學(xué)至紅外能譜分布,發(fā)現(xiàn)這2個源是II型年輕恒星體,即有原初行星盤。換而言之,我們在AKARI/FIS的年輕恒星體樣本中共找到了2個長壽命原行星盤。利用Liu的理論模型對這兩個源做能譜擬合,得到了中心星的光度和有效溫度,繼而利用Siess的前主序演化軌跡得出這兩個源的年齡分別為14.1±4.2Myr和16.8±4.4Myr。長壽命原行星盤的存在對行星及其宿主恒星的形成有重要影響。
[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 鹵4.2Myr and 16.8 鹵4.4 Myr, respectively. The existence of long-lived protoplanetary disk has an important influence on the formation of planets and their host stars.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：P141.91
本文編號：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 鹵4.2Myr and 16.8 鹵4.4 Myr, respectively. The existence of long-lived protoplanetary disk has an important influence on the formation of planets and their host stars.
【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：P141.91
【共引文獻(xiàn)】
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2 Ya-Fang Huang;Jin-Zeng Li;Travis A.Rector;Zhou Fan;;Investigation of star formation toward the Sharpless 155 H II region[J];Research in Astronomy and Astrophysics;2014年10期
3 徐雪芳;李兟;任致遠(yuǎn);;云核質(zhì)量函數(shù)[J];天文學(xué)進(jìn)展;2014年03期
4 寧長春;張輝杰;;大質(zhì)量恒星形成區(qū)中CO分子外向流的觀測和研究[J];西藏大學(xué)學(xué)報(自然科學(xué)版);2013年02期
相關(guān)碩士學(xué)位論文 前1條
1 李志廣;大質(zhì)量恒星形成區(qū)的亞毫米波觀測研究[D];中國科學(xué)院研究生院（云南天文臺）;2013年
，本文編號：2328941
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