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The debris disk candidates:eleven 24μm excess stars in the Spitzer SWIRE fields

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Research in Astronomy and Astrophysics 2012年第5期12卷 513-528页

作者： Hong Wu Chao-Jian Wu Chen Cao Sebastian Wolf jing-yao hu Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Department of Astronomy Beijing Normal University Beijing 100875 China Institute of Space Science and Physics Shandong University at Weihai Weihai 264209 China Shandong Provincial Key Laboratory of Optical Astronomy ＆ Solar-Terrestrial Environment Weihai 264209 China Max Planck Institute for Astronomy K6nigstuhl 17 69117 Heidelberg Germany

We present the optical to mid-infrared SEDs of 11 debris disk candidates from Spitzer SWIRE fields. All the candidates are selected from SWIRE 24 μm sources matched with both the SDSS star catalog and the 2MASS point source catalog. They show an excess in the mid-infrared at 24 μm （Ks-[24]vega 〉 0.44）, indicating the presence of a circumstellar dust disk. The observed optical spectra show that they are all late-type main-sequence stars covering the spectral types of FGKM. Their fractional luminosities are well above 5× 10-5, even up to the high fractional luminosity of 1×10-3. The high galactic latitudes of SWIRE fields indicate that most of these candidates could belong to the oldest stars in the thick disk. Our results indicate that high fractional luminosity debris disks could exist in old solar-like star systems, though they are still quite rare. Their discovery at high galactic latitudes also provides an exellent opportunity for further study of the properties and evolution of debris disks in regions of the Galaxy with low densities of ISM, called ISM poor environments.

关键词： infrared stars -- planetary systems protoplanetary disks - stars for marion

Multiwavelength study of nearly face-on low surface brightness disk galaxies

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Research in Astronomy and Astrophysics 2010年第12期10卷 1223-1241页

作者： Dong Gao Yan-Chun Liang Shun-Fang Liu Guo-hu Zhong Xiao-Yan Chen Yan-Bin Yang Francois Hammer Guo-Chao Yang Li-Cai Deng jing-yao hu National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China ycliang @ nao. cas. cn dgao @ nao. cas. cn Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of Chinese Academy of Sciences Beijing 100049 China GEPI Observatoire de Paris-Meudon 92195 Meudon France Department of Physics Hebei Normal University Shijiazhuang 050016 China

We study the ages of a large sample （1802） of nearly face-on disk low surface brightness galaxies （LSBGs） using the evolutionary population synthesis （EPS） model PEGASE with an exponentially decreasing star formation rate to fit their mul- tiwavelength spectral energy distributions （SEDs） from far-ultraviolet （FUV） to nearinfrared （NIR）. The derived ages of LSBGs are 1-5 Gyr for most of the sample no matter if constant or varying dust extinction is adopted, which are similar to most of the previous studies on smaller samples. This means that these LSBGs formed the majority of their stars quite recently. However, a small part of the sample （~2%-3%） has larger ages of 5-8 Gyr, meaning their major star forming process may have occurred earlier. At the same time, a large sample （5886） of high surface brightness galaxies （HSBGs） are selected and studied using the same method for comparisons. The de- rived ages are 1-5 Gyr for most of the sample （97%） as well. These results probably mean that these LSBGs have not much different star formation histories from their HSBGs counterparts. However, we should notice that the HSBGs are generally about 0.2 Gyr younger, which could mean that the HSBGs may have undergone more recent star forming activities than the LSBGs.

关键词： galaxies: evolution -- galaxies: formation -- galaxies: photometry --galaxies: spiral -- galaxies: statistics -- ultraviolet: galaxies

Photometric Calibration of the Lunar-based Ultraviolet Telescope for Its First Six Months of Operation on the Lunar Surface

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Research in Astronomy and Astrophysics 2015年第7期15卷 1068-1076页

作者： jing Wang Li Cao Xian-Min Meng Hong-Bo Cai jing-Song Deng Xu-hui Han Yu-Lei Qiu Fang Wang Shen Wang Wei-Bin Wen Chao Wu Jian-Yan Wei jing-yao hu National Astronomical Observatories Chinese Academy of Sciences Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of Sciences Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of Sciences

We describe the photometric calibration of the Lunar-based Ultraviolet Telescope（LUT）, the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surface. Two spectral datasets（set A and B） from near-ultraviolet（NUV） to the optical band were constructed with 44 International Ultraviolet Explorer（IUE） standards, because of the LUT＇s relatively wide wavelength coverage. Set A was obtained by extrapolating the IUE NUV spectra（λ 〈 3200 ） to the optical band based upon the theoretical spectra of stellar atmosphere models. Set B was composed of theoretical spectra from 2000  to 8000 extracted from the same model grid. In total, seven standards have been observed in15 observational runs until May 2014. The calibration results show that the photometric performance of LUT is highly stable in its first six months of operation. The magnitude zero points obtained from the two spectral datasets are also consistent with each other, i.e., zp = 17.54 ± 0.09 mag（set A） and zp = 17.52 ± 0.07 mag（set B）.

关键词： space vehicles: instruments -- telescopes -- techniques: photometric --ultraviolet: general

The photometric system of the Tsinghua-NAOC 80-cm telescope at NAOC Xinglong Observatory

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Research in Astronomy and Astrophysics 2012年第11期12卷 1585-1596页

作者： Fang huang Jun-Zheng Li Xiao-Feng Wang Ren-Cheng Shang Tian-Meng Zhang jing-yao hu Yu-Lei Qiu Xiao-Jun Jiang Astronomy Department Beijing Normal University Beijing 100875 China Physics Department and Tsinghua Center for Astrophysics Tsinghua University Beijing100084 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academyof Sciences Beijing 100012 China

The Tsinghua-NAOC （National Astronomical Observatories of China） Telescope （hereafter, TNT） is an 80-cm Cassegrain reflecting telescope located at the Xinglong Observatory of NAOC, with the main scientific goals of monitoring various transients in the universe such as supernovae, gamma-ray bursts, novae, variable stars, and active galactic nuclei. We present a systematic test and analysis of the photometric performance of this telescope. Based on the calibration observations taken on 12 pho- tometric nights, spanning the period from 2004 to 2012, we derived an accurate trans- formation equation between the instrumental ubvri magnitudes and standard Johnson UBV and Cousins RI magnitudes. In particular, the color terms and the extinction coefficients of different passbands are well determined. With these data, we also ob- tained the limiting magnitudes and the photometric precision of TNT. It is worthwhile to point out that the sky background at the Xinglong Observatory became gradually worse over the period from 2005 to 2012 （e.g., -21.4 mag vs. ,-20.1 mag in the V band）.

关键词： instrumentation detectors -- site testing -- telescopes

1RXS J232953.9+062814: a New SU UMa Dwarf Nova below the Period Minimum

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Chinese Journal of Astronomy and Astrophysics 2001年第6期1卷 483-486页

作者： Jian-Yan Wei, Xiao-Jun Jiang, Da-Wei Xu, Ai-Ying Zhou and jing-yao hu National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

RXS 1232953.9+062814 was identified as a cataclysmic variable by Wei et al. (1999). Four low-resolution spectra of 1RXS J232953.9+062814 were obtained with the 2.16-rn telescope of the National Astronomical Observatories, of which two were at outburst, and two were at quiescence. The system is about 16.8 B and 16.5 V at quiescence, and 12.6 B and 12.6 V at outburst. The quiescent spectra were dominated by double-peaked Balmer emissions, which indicates a hydrogen-rich system with a high-inclination accretion disc. MgH and TiO absorption bands appeared in the quiescent spectrum which implies a companion with a spectral type of early M dwarf. If we take it as a MO dwarf, then the system is located at a distance of 350 pc with a proper motion velocity 150 km s-1. The superhump period of 0.046311 days was confirmed by our V photometry. The short period and the hydrogen-rich nature reveal that this system is another SU Ursae Majoris-type dwarf nova below the period minimum after V485 Centauri. 1RXS J23 2953.9+062814 is one of the most important systems for studying the evolutionary scenario of cataclysmic variables since it is much brighter than V485 Cen.

关键词： stars: dwarf novae - stars: cataclysmic variables: individual: 1RXS J232953.9 +062814

A sodium laser guide star coupling efficiency measurement method

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Research in Astronomy and Astrophysics 2016年第9期16卷 95-100页

作者： Lu Feng Zhi-Xia Shen Suijian Xue Yang-Peng Li Kai Jin Angel Otarola Yong Bo Jun-Wei Zuo Qi Bian Kai Wei jing-yao hu Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China The Institute of Optics and Electronics Chinese Academy of Sciences Chengdu 610209 China Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 China Thirty Meter Telescope Corporation Pasadena California USA

A large telescope＇s adaptive optics （AO） system requires one or more bright artificial laser guide stars to improve its sky coverage. The recent advent of a high power sodium laser is perfect for such application. However, besides the output power, other parameters of the laser also have a significant impact on the brightness of the generated sodium laser guide star, mostly in non-linear relationships. When tuning and optimizing these parameters it is necessary to tune based on a laser guide star generation performance metric. Although return photon fluxis widely used, variability of the atmosphere and sodium layer makes it difficult to compare results from different sites or even within a short time period for the same site. A new metric, coupling efficiency, is adopted in our field tests. In this paper, we will introduce our method for measuring the coupling efficiency of a 20W class pulse sodium laser for AO application during field tests that were conducted during 2013-2015.

关键词： instrumentation adaptive optics -- methods observational -- atmospheric effects

Vilnius Photometry and Reddening of the Young Open Cluster NGC 6913

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Chinese Journal of Astronomy and Astrophysics 2001年第4期1卷 333-343页

作者： Jun-Jie Wang and jing-yao hu (National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100012 Chinese Academy of Sciences-Peking University Joint Beijing As Chinese Academy of Sciences-Peking University Joint Beijing Astrophysical Center Beijing 100871

stars in the NGC 6913 field with both UBV and Vilnius photometry are selected to be the sample. The membership probability of the stars is greater than 50%. The correlation among Vilnius photometry, UBV photometry and reddening in the cluster is reviewed. It is found that the photometry in the Vilnius X, Y and Z bands can be used to make rough spectral classification. The values of E(B - V) are well correlated with the Vilnius colors of X - Y, Y - Z, Z - V and V - S in NGC 6913. The ratio of (V - S)/(Y - Z) of the MPCM (Most Possible Cluster Members) is a constant (1.30 -±0.06), and has no effect on the values of E(B - V), (B - V)0 and V0. Comparing with the observational data of all the stars of NGC 6913 region, we propose that the value of (V - S)/(Y - Z) can probably be used to select the preliminary candidates of one open cluster. In addition, 12 variable stars are discovered in the NGC 6913 region, in which star #155 has a variation with an amplitude of 4.25 mag.

关键词： Galaxy: open clusters and associations - ISM: dust extinction

A GRB Follow-up System at the Xinglong Observatory and Detection of the High-Redshift GRB 060927

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Chinese Journal of Astronomy and Astrophysics 2008年第6期8卷 693-699页

作者： Wei-Kang Zheng Jin-Song Deng Meng Zhai Li-Ping Xin Yu-Lei Qiu jing Wang Xiao-Meng Lu Jian-Yan Wei jing-yao hu National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate School of Chinese Academy of Sciences Beijing 100049 China

A gamma-ray burst （GRB） optical photometric follow-up system at the Xinglong Observatory of National Astronomical Observatories of China （NAOC） has been constructed. It uses the 0.8-m Tsinghua-NAOC Telescope （TNT） and the 1-m EST telescope, and can au- tomatically respond to GRB Coordinates Network （GCN） alerts. Both telescopes slew relatively fast, being able to point to a new target field within - 1 min upon a request. Whenever available, the 2.16-m NAOC telescope is also used. In 2006 the system responded to 15 GRBs and detected seven early afterglows. In 2007 six GRBs have been detected among 18 follow- up observations. TNT observations of the second most distant GRB 060927 （z = 5.5） are shown, which started as early as 91 s after the GRB trigger. The afterglow was detected in the combined image of the first 19 × 20 s unfiltered exposures. This GRB follow-up system has joined the East-Asia GRB Follow-up Observation Network （EAFON）.

关键词： gamma-rays: bursts gamma-rays: observations telescopes

A catalog of early-type emission-line stars and Hα line profiles from LAMOST DR2

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Research in Astronomy and Astrophysics 2016年第9期16卷 39-50页

作者： Wen Hou A-Li Luo jing-yao hu Hai-Feng Yang Chang-De Du Chao Liu Chien-De Lee Chien-Cheng Lin Yue-Fei Wang Yong Zhang Zi-huang Cao Yong-hui Hou Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China University of Chinese Academy of Sciences Beijing 100049 China School of Computer Science and Technology Taiyuan University of Science and Technology Taiyuan 030024 China Institute of Astronomy National Central University Jhongli Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China Nanjing Institute of Astronomical Optics & Technology National Astronomical Observatories Chinese Academy of Sciences Nanjing 210042 China

We present a catalog including 11 204 spectra of 10436 early-type emission-line stars from LAMOST DR2, among which 9752 early-type emission-line spectra are newly discovered. For these early- type emissionqine stars, we discuss the morphological and physical properties of their low-resolution spectra. In this spectral sample, the Hα emission profiles display a wide variety of shapes. Based on the Hα line profiles, these spectra are categorized into five distinct classes： single-peak emission, single-peak emission in absorption, double-peak emission, double-peak emission in absorption, and P-Cygni profiles. To better understand what causes the Hc~ line profiles, we divide these objects into four types from the perspective of physical classification, which include classical Be stars, Herbig Ae/Be stars, close binaries and spectra contaminated by H n regions. The majority of Herbig Ae/Be stars and classical Be stars are identified and separated using a （H-K, K-W1） color-color diagram. We also discuss 31 binary systems that are listed in the SIMBAD on-line catalog and identify 3600 spectra contaminated by HⅡ regions after cross-matching with positions in the Dubout-Crillon catalog. A statistical analysis of line profiles versus classifications is then conducted in order to understand the distribution of Hc~ profiles for each type in our sample. Finally, we also provide a table of 172 spectra with Fen emission lines and roughly calculate stellar wind velocities for seven spectra with P-Cygni profiles.

关键词： stars early-type - stars emission-line, Be -- stars pre-main sequence -- binaries close