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| 1 | Relative flux calibration for the Guoshoujing Telescope (LAMOST)显示文摘This paper presents a relative flux calibration method for the Guoshoujing Telescope (LAMOST), which may be applied to connect a blue spectrum to a red spectrum to build the whole spectrum across the total wavelength range (3700 ~ 9000 A). In each spectrograph, we estimate the effective temperatures of selected stars using a grid of spectral line indices in the blue spectral range and a comparison with stellar atmosphere models. For each spectrograph, stars of types A and F are selected as pseudo-standard stars, and the theoretical spectra are used to calibrate both the blue (3700 ~ 5900 A) and red spectrograph arms (5700 ~ 9000 A). Then the spectral response function for these pseudo-standard stars could be used to correct the raw spectra provided by the other fibers of the spectrograph, after a fiber efficiency function has been derived from twilight flat-field exposures. A key problem in this method is the fitting of a pseudo stellar continuum, so we also give a detailed description of this step. The method is tested by comparing a small sample of LAMOST spectra calibrated in this way on stars also observed by the Sloan Digital Sky Survey. The result shows that the T eff estimation and relative flux calibration method are adequate. | Yi-Han Song A-Li Luo Georges Comte Zhong-Rui Bai Jian-Nan Zhang Wei Du Hao-Tong Zhang Jian-Jun Chen Fang Zuo Yong-Heng Zhao | 2012 | Research in Astronomy and Astrophysics2012，12，4： | 4 |
| 2 | LAMOST类星体[OIII]线附近天光背景扣除显示文摘扣除天光背景的好坏是影响谱线信噪比很重要的因素,同时由于天光光纤数量有限以及光谱仪漂移等多方面因素的影响导致减天光是光纤光谱数据处理中公认的难点。目前已有的减天光方法主要是针对全谱的天光成分扣除,没有关注在特殊谱线位置上的局部天光情况,尤其是低红移类星体非常重要的[OIII]线附近的天光背景。探索了一种局部精细的天光背景扣除方法,解决了类星体中Hβ-[OIII]的宽线经常受到减天光精度干扰的问题。利用LAMOST减天光前的原始流量以及相对流量改正数据,根据同一观测天区的超级天光光谱对背景进行扣除。实验结果表明,在不同红移类星体中,该方法减天光后Hβ-[OIII]区间的光谱质量相对于原始LAMOST光谱批处理程序都有了明显的提高,这更有利于后续的谱线分析,同时为少部分LAMOST光谱批处理程序没处理好的特殊光谱提供了补充的解决方法。该方法目前已应用于搜寻双峰活动星系核候选体的预处理中。 | 石志鑫 Georges Comte 罗阿理 屠良平 赵永恒 吴福朝 | 2014 | 光谱学与光谱分析2014，34，11： | 3 |
| 3 | Nearby M subdwarfs from LAMOST data release 2显示文摘We identify 108 M subdwarfs(sd Ms) out of more than two hundred thousand M type spectra from the second data release(DR2) of the LAMOST regular survey. This sample, among which 58 members are identified for the first time, includes 33 extreme subdwarfs(esd Ms) and 11 ultra subdwarfs(usd Ms).The selection is based on the usual ratio of absorption depth of Ca H2, Ca H3 and TiO 5 band systems.We also emphasize the use of the Ca H1 band. We provide estimates of spectral subtype(SPT), L′epine metallicity index ζ, effective temperature and [Fe/H]. Both ζ–[Fe/H] and SPT–Teff figures show reasonable consistency; compared to PHOENIX model spectra, average rounded values of [Fe/H] for sd Ms, esd Ms and usd Ms are respectively –0.5, –1 and –1.5. The photometric distances are estimated, indicating that most sources are located within 500 pc of the Sun and 350 pc of the Galactic disk. Velocities and 3D Galactic motions are also briefly discussed. Among the 108 subdwarfs, seven stars appear to be active with a significant Hα emission line. The source LAMOST J104521.52+482823.3 is a white dwarf- M subdwarf binary, while LAMOST J123045.52+410943.8, also active, exhibits carbon features in red. | Yu Bai A-Li Luo Georges Comte Jing-Kun Zhao Hai-Feng Yang Yan-Xin Guo You-Fen Wang Yin-Bi Li Bing Du Wen Hou Xiao Kong Zhen-Ping Yi Yi-Han Song Zhong-Rui Bai Jian-Nan Zhang Meng-Xin Wang Jian-Jun Chen Xiao-Yan Chen Ke-Fei Wu Fang Zuo Yue Wu Zi-Huang Cao Yong-Hui Hou Yue-Fei Wang Yong Zhang | 2016 | Research in Astronomy and Astrophysics2016，16，7： | 0 |
| 4 | A search for double-peaked narrow emission line galaxies and AGNs in the LAMOST DR1显示文摘The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) has released more than two million spectra,which provide the opportunity to search for double-peaked narrow emission line(NEL) galaxies and active galactic nuclei(AGNs).The double-peaked narrow-line profiles can be well modeled by two velocity components,respectively blueshifted and redshifted with respect to the systemic recession velocity.This paper presents 20 double-peaked NEL galaxies and AGNs found from LAMOST DR1 using a search method based on a multi-Gaussian fit of the narrow emission lines.Among them,ten have already been published by other authors,either listed as genuine double-peaked NEL objects or as asymmetric NEL objects,and the remaining ten are original discoveries.We discuss some possible origins for the double-peaked narrow-line features,such as interaction between jet and narrow line regions,interaction with companion galaxies,and black hole binaries.Spatially resolved optical imaging and/or follow-up observations in other spectral bands are needed to further discuss the physical mechanisms at work. | Zhi-Xin Shi A-Li Luo Georges Comte Xiao-Yan Chen Peng Wei Yong-Heng Zhao Fu-Chao Wu Yan-Xia Zhang Shi-Yin Shen Ming Yang Hong Wu Xue-Bing Wu Hao-Tong Zhang Ya-Juan Lei Jian-Nan Zhang Ting-Gui Wang Ge Jin Yong Zhang | 2014 | Research in Astronomy and Astrophysics2014，14，10： | 0 |
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