Effect of the Initial Mass Function of Primaries on Binary Stellar Populations

Using evolutionary population synthesis technique, we explore the behaviour of the integrated U-B,B-V, V-R and R - I colours, the integrated spectral energy- distributions (ISEDs) and Lick/IDS absorption-line indices of instantaneous burst solar-metallicity binary stellar populations, as a function of the initial mass function (IMF)of primaries. It is found that the variation of the IMF of primaries produces a small effect on the integrated colours and the Lick/IDS indices, while a significant difference in the absolute ISEDs.     

AGB/FGB星的核质量-恒星光度关系和核质量-恒星半径关系

根据最新的恒星演化模型网络 ,系统地研究了AGB/FGB星的核质量 恒星光度关系和核质量 恒星半径关系 .基于最新的恒星演化模型 ,给出了最新的AGB/FGB星的核质量 恒星光度唯一关系 ,以及星族I和星族IIAGB/FGB星的核质量 恒星半径关系 .核质量 恒星光度关系基本上不受恒星参量 (如金属丰度、混合程参量α、星风物质损失 )的影响 .而核质量 恒星半径关系则受恒星参量的影响 .对同一核质量 ,星族IIAGB/FGB星的半径比星族I的小 (约 1 5倍 ) .α增大也导致AGB/FGB星的半径减小 .     

2012年,参宿四会爆炸吗?

恒星是宇宙的基本组成单元,中小质量的恒星(如太阳)占绝大部分.中小质量的恒星演化到最后,外壳被损失掉,成为漂亮的行星状星云,而恒星的核则成为白矮星.大质量恒星演化到最后会发生超新星爆炸,产生巨大的能量,留下一个中子星或黑洞.参宿四是一颗大质量恒星,种种迹象表明,它将发生超新星爆炸,但在2012年爆炸的可能性微乎其微,天上不会出现两个"太阳",也不会对地球上人们的生活产生实质性的影响.     

Evolutionary Population Synthesis for Single Stellar Populations

Using the evolutionary population synthesis technique,we present the latest integrated colurs for instantaneous burst single stellar populations(SSPs) of different metallicities and we investigate their colour evolution.Unlike previous research,we adopt the stellar evolutionary models that employ amongst other things ,recent opacities and a revised equation of state(EOS),and include evolutionary processes such as convective overshooting,thermal pulses and dredge-up,The models are used in the convenient form of analytical fitting functions.In addition,we use the BaSeL model for the library of stellar spectra,This model provides an extensive low-resolution theoretical flux distribution and UBVRIJHKLM colours,which have been calibrated empirically or semi-empirically,for a wide range of stellar parameters.     

钱德拉塞卡对二十世纪科学的贡献

两千多年来,天文学家一直认为宇宙是完美而宁静的,19岁的Chandrasekha在前往英格兰读研究生途中的一个计算结果敲响了完美宁静宇宙观终结的钟声. 2010年12月出版的Physics Today杂志上,刊登了Dyson撰写的Chandrasekha(钱德拉塞卡)对二十世纪科学的贡献一文.该文基于他在2010年10月16日芝加哥大学举行的Chandrasekhar百年诞辰庆典时的演讲稿,详细地介绍了Chandrasekhar的科学生涯以及对二十世纪科学的杰出贡献.     

双中子星的星族合成研究

双中子星是天体物理中重要的研究对象,对于许多研究领域都有重要作用。2017年LIGO/Virgo发现第一个双中子星并合事件GW170817,开启了用引力波探测发现双中子星的序幕。文章主要介绍了双中子星的双星演化通道,以及双中子星星族合成的一些性质。此外,还介绍了双星演化中的一些不确定性以及形成GW170817双中子星的双星演化通道。     

LAMOST medium-resolution spectroscopic survey of binarity and exotic star (LAMOST-MRS-B): Observation strategy and target selection

LAMOST-MRS-B is one of the sub-surveys of LAMOST medium-resolution ($R\sim7500$) spectroscopic survey. It aims at studying the statistical properties (e.g., binary fraction, orbital period distribution, mass ratio distribution) of binary stars and exotic stars. We intend to observe about 30000 stars ($10 {\rm mag}\leq G < 14.5$ mag) with at least 10 visits in five years. We first planned to observe 25 plates around the galactic plane in 2018. Then the plates were reduced to 12 in 2019 because of the limitation of observation. At the same time, two new plates located at the high galactic latitude were added to explore binary properties influenced by the different environments. In this survey project, we set the identified exotic and low-metallicity stars with the highest observation priorities. For the rest of the selected stars, we gave the higher priority to the relatively brighter stars in order to obtain high quality spectra as many as possible. Spectra of 49129 stars have been obtained in LAMOST-MRS-B field and released in DR8, of which 28828 and 3375 stars have been visited more than twice and ten times with $\rm SNR \geq 10$, respectively. Most of the sources are B-, A-, and F-type stars with $\rm -0.6< [Fe/H] < 0.4 $ dex. We also obtain 347 identified variable and exotic stars and about 250 stars with $\rm [Fe/H] <-1$ dex. We measure radial velocities (RVs) by using 892233 spectra of the stars. The uncertainties of RV achieve about $1$ ${\rm km \cdot s^{-1}}$and $10$ ${\rm km \cdot s^{-1}}$ for 95% of late- and early-type stars, respectively. The datasets presented in this paper are available at http://www.doi.org/10.57760/sciencedb.j00113.00035.