ELUCIDATION OF ORIGINS OF STELLAR MASS WITH WIDE FIELD IR SURVEYS: IMF IN STAR FORMATION

这项研究旨在建立恒星的初始质量函数(IMF)，包括棕矮星等极低质量恒星，甚至行星质量天体。为此，我们对恒星形成区进行了非常广泛的红外探测。因为红外探测可以发现嵌入的星团，其质量分布反映了国际货币基金组织。此外，由于年轻恒星由于其引力能量而在红外线上相对明亮，我们可以探测到质量极低的恒星。我们可以根据年轻恒星的颜色和偏振信息来区分背景恒星和年轻恒星。主要研究结果如下：(1)对附近恒星形成区进行了观测。随着IRSF 1.4米望远镜在南非，斯巴鲁和双子座望远镜在夏威夷。在IRSF的实验是使用天狼星JHKs波段同步相机进行的，该相机由NAOJ和Naoya大学共同开发。观测区域有Oph、Cha、RCRA、猎户座、船帆、天鹅座分子云。我们在一些区域探测到了一些新的棕矮星和行星质量候选者。猎户座、S106和船帆区域的研究结果已经发表在相关期刊上。我们发现了褐矮星的普遍性以及极低质量星与低质量星的相对数量因地区而异。(2)我们在麦哲伦桥上发现了中等质量的年轻恒星(发表在参考期刊上)。(3)我们为IRSF/天狼星研制了广视场红外偏振仪，并进行了偏振观测。我们探测到了许多新的星周结构。(4)我们对Oph云核进行了光度测量和光谱分析，发现了质量最低的候选星。

This research aims to establish the initial mass function (IMF) of stars, including very low-mass stars such as brown dwarfs and even planetary mass objects. In order to this, we have conducted very wide field infrared surveys of star forming regions. Since infrared surveys can uncover the embedded stellar clusters whose mass distribution reflects the IMF. In addition, because the young stars are relatively bright at infrared due to their gravitational energy, we can detect down to very low mass stars. We can distinguish young stars from background stars taking into account their color and polarization information. The mains results are summarized as follows:(1)We conducted observations of nearby star forming regions. with the IRSF 1.4m telescope in South Africa, the Subaru and Gemini telescopes in Hawaii. Those at IRSF were conducted with the SIRIUS JHKs-band simultaneous camera, which was developed by NAOJ and Naoya University. The observed regions are Oph, Cha, R CrA, Orion, Vela, Cygnus molecular clouds. We have detected a number f new brown dwarfs and planetary mass candidates in some regions. The results for Orion, S106, and Vela regions were already published in refereed journals. We have discovered the universality of brown dwarfs and the relative populations of very low mass stars to low mass stars vary from region to region.(2)We discovered the middle mass young stars in the Magellanic Bridge (published in refereed journal).(3)We developed wide field infrared polarimeter for IRSF/SIRIUS and conducted polarization observations. We detected a number of new circumstellar structures.(4)We conducted photometry and spectroscopy of the Oph cloud core and found lowest mass candidates.