Contributions of Rotation,Expansion and Line Broadening to the Morphology and Kinematics of the Inner CSE of Oxygen-rich AGB Star R Hya

We use archival ALMA observations of the CO(2-1)and SiO(5-4)molecular line emissions of AGB star R Hya to illustrate the relative contributions of rotation,expansion and line broadening to the morphology and kinematics of the circumstellar envelope(CSE)within some~70 au(~0."5)from the centre of the star.We give evidence for rotation and important line broadening to dominate the inner region,within~14 au(~100 mas)from the centre of the star.The former is about an axis that projects a few degrees west of north and has a projected rotation velocity of a few km s^(-1).The latter occurs within some 7-14 au(50-100 mas)from the centre of the star,with the line width reaching two to three times its value outside this region.We suggest that it is caused by shocks induced by stellar pulsations and convective cell granulation.We show the importance of properly accounting for the observed line broadening when discussing rotation and evaluating the radial dependence of the rotation velocity.

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

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.

星线共混型SBS改性沥青制备及其微观特性研究

为解决现有线型SBS改性沥青改性剂掺量高、沥青性能稳定性差的问题,基于分子自组装原理,借助阻聚剂,进行星线共混型SBS改性沥青制备方法研究,并评估星型SBS替代部分线型SBS,实现降低SBS掺量的可行性;利用基础三大指标确定力学性能,动态剪切流变仪确定粘弹性能,并进行红外光谱与荧光显微分析。结果表明:0.2%阻聚剂、3.3%改性剂的星线共混改性沥青三大指标与纯线3.8%SBS改性沥青相当,可降低0.5%SBS掺量,星线共混型SBS改性沥青高温性能更好,反应更加完全,形成的网络结构更完善。

Searching for classical Be stars in LAMOST DR1

We report on searching for Classical B-type emission-line（CBe） stars in the first data release of the Large Sky Area Multi-Object fiber Spectroscopic Telescope（LAMOST; also called the Guo Shou Jing Telescope）. A total of 192 objects（including 12 previously known CBes） were identified as CBe candidates with prominent He I λ4387, He I λ4471 and Mg II λ4481 absorption lines, as well as Hβλ4861and Hαλ6563 emission lines. These candidates significantly increase the currently known sample of CBes by about 8%. Most of the CBe candidates are distributed near the Galactic Anti-Center due to the observing strategy used for LAMOST. Only two CBes are in star clusters. These two CBes have ages of 15.8 and 398 Myr, respectively.

在线蓝星灰镀膜玻璃工艺及其排气装置

通过设计原料配方、限定着色剂、控制熔窑温度及其镀膜掺杂剂等关键成套生产工艺,制备出在370~690nm可见光时呈现出“蓝星灰”色彩的镀膜玻璃以满足市场需求,同时在镀膜器上游位置增加一对排气装置,增加了镀膜过程中锡槽低温区排废能力,避免污染物掉落在玻璃板上,从而解决针孔数量超标现象,降低因频繁吹槽而造成的产量损失。

PC生产线自动布料机研究

混凝土预制件(Precast Concrete,PC)生产线是支撑建筑产业工业化和现代化发展的关键装备,布料机是PC生产线的核心设备,对生产线的自动化程度、可靠性、工作效率及构件质量有着决定性影响。通过研究自动布料机布料装置和控制系统,提供一种切实可行的自动布料解决方案,同时指出布料机未来的发展方向。

Optical/IR studies of Be stars in NGC 6834 with emphasis on two specific stars

We present optical and infrared photometric and spectroscopic studies of two Be stars in the 70-80-Myr-old open cluster NGC 6834. NGC 6834（1） has been reported as a binary from speckle interferometric studies whereas NGC 6834（2） may possibly be a γ Cas-like variable. Infrared photometry and spectroscopy from the United Kingdom Infrared Telescope （UKIRT）, and optical data from various facilities are combined with archival data to understand the nature of these candidates. High signal-to-noise near-IR spectra obtained from UKIRT have enabled us to study the optical depth effects in the hydrogen emission lines of these stars. We have explored the spectral classification scheme based on the intensity of emission lines in the H and K bands and contrasted it with the conventional classification based on the intensity of hydrogen and helium absorption lines. This work also presents hitherto unavailable UBV CCD photometry of NGC 6834, from which the evolutionary state of the Be stars is identified.

Irregular changes in Hαemission line of V423 Aur observed by LAMOST Medium-Resolution Spectrographs

We obtained seven spectra of the Be star V423 Aur on 2017 Dec.5 using the LAMOST MediumResolution Spectrograph with exposures from 600 to 1200 seconds.These spectra show the irregular Ha emission line profile variations(LPVs).In the seven spectra,from the 4 th to 7 th,the left part of Ha profile even shows excess.However,no variation can be seen from the follow-up observation of photometry by 1.26-m telescope and High-Resolution spectra by 2.16-m telescope.According to the High-Resolution spectra,we conclude that it is a B7 V type star with E(B-V)=0.709±0.036 and its vsini is221.8 km s-1.The short-term Ha LPVs could be explained as a result of the transient ejection of matter from rotating disk or shell around V423 Aur.

Infall and Outflow Activities in the Be star FY CMa

Unusual activity of outflow mass motion connected with infall events was recorded for the B0.5 IVe star FY CMa in February 1987 from both archival IUE spectrograms of circumstellar N v resonance lines and optical spectra of Ha and HeI γ5876 A emission lines which showed inverse P Cygni-type profiles. We estimate the mass loss rate using ultraviolet Si IVresonance lines with expanding atmosphere modeling calculations, and describe how the radial pressure performs the dominant role in accelerating the stellar wind. We attempt to give a qualitative explanation for the activity observed for FY CMa in terms of circumstellar matter raining down to the star.

High-Resolution Spectroscopy of Winds Associated with T Tauri Stars

We carried out optical high-resolution spectroscopy of T Tauri stars using the Subaru Telescope. Using archived data from the Keck Telescope and the Very Large Telescope, we detected forbidden lines of [S II] at 4069A, in addition to those of [O I] at 5577 A and 6300A, for 13 T Tauri stars. We consider that low-velocity components of these forbidden lines emanate from the wind associated with T Tauri stars. Using two flux ratios of the three lines, we simultaneously determined the hydrogen density and temperature of the winds. The winds ofT Tauri stars have a hydrogen density of 2.5 × 106 cm^-3 - 2.5 × 10^9 cm^-3 and a temperature of 10 800 -18 000 K. The mass loss rates by the wind are estimated to lie in the range from 2.0 × 10^-10 M⊙ yr-1 to 1.4× 10^-9 M⊙ yr-1. The mass loss rates are found to increase with increasing mass accretion rates. The ratio of the mass loss rate to the mass accretion rate is 0.001-0.1 for classical T Tauri stars and 0.1-1 for transitional disk objects.

Morphology and kinematics of the gas envelope of the variable AGB star π^1 Gruis

Observations of the ^12CO（3–2） emission from the circumstellar envelope（CSE） of the variable star π1Gru using the compact array of the ALMA observatory have been recently made accessible to the public. An analysis of the morphology and kinematics of the CSE is presented with a result very similar to that obtained earlier for ^12CO（2–1） emission using the Submillimeter Array. A quantitative comparison is made using their flared disk model. A new model is presented that provides a significantly better description of the data, using radial winds and smooth evolutions of the radio emission and wind velocity from the stellar equator to the poles.

Spectroscopic study of Be-shell stars:4 Her and 88 Her

We present an optical spectroscopic study based on 41 spectra of 4 Her and 32 spectra of 88 Her, obtained over a period of 6 months. We estimate the rotational velocity of these stars from HeI lines in the blue spectral region （4000-4500 A）. We find that these stars are likely to be rotating at a fractional critical rotation of -0.80. We measure the average Ip/lc ratio to quantify the strength of the Ha line and obtain 1.63 for 4 Her and 2.06 for 88 Her. The radius of the Ha emission region is estimated to be Ra/R. -5.0, assuming a Keplerian disk. These stars are thus found to be fast rotators with a relatively small Hoe emission region. We detect V/R variation of the Ha spectral line during the observed period. We re-estimate the periods for both stars and obtain a period of ,-46 d and its harmonic of 23.095 d for 4 Her, and a period of -86 d for 88 Her. As these two cases are shell stars with binaries and have low Ha EW with the emission region closer to the central star, the V/R variation and a change in period may be an effect of the binary on the circumstellar disk.

An infrared study of Be stars based on ISO SWS01 spectra

The Infrared Space Observatory （ISO） Short-Wavelength Spectrometer （SWS） spectra of 10 Be stars are presented. It can be seen that the Be stars show a diversity in their ISO SWS01 spectral classifications by Kraemer et al., from naked stars, stars associated with dust, stars with warm dust shells, stars with cool dust shells to very red sources. In addition, the Brα/HI（14-6） line flux ratio derived for the sample stars is compared with that of P Cyg, and it is found that the line ratio of Be stars which were investigated show not only lower values as suggested by Waters et al., but also larger values. Therefore, the line ratio cannot be used to judge whether a star is a Be star or not.

Studies of a possible new Herbig Ae/Be star in the open cluster NGC 7380

We present a study of the star 2MASS J22472238＋5801214 with the aim of identifying its true nature which has hitherto been uncertain. This object, which is a member of the young cluster NGC 7380, has been variously proposed to be a Be star, a D-type symbiotic and a Herbig Ae/Be star in separate studies. Here we present optical spectroscopy, near-IR photometry and narrow band Hα imaging of the nebulosity in its environment. Analysis of all these results, including the spectral energy distribution constructed from available data, strongly indicate the source to be a Herbig Ae/Be star. The star is found to be accompanied by a nebulosity with an interesting structure. A bow-shock shaped structure, similar to a cometary nebula, is seen very close to the star with its apex oriented towards the photoionizing source of this region （i.e. the star DH Cep）. An interesting spectroscopic finding, from the forbidden [StI] 6716, 6731A and [OI] 6300A lines, is the detection of a blue-shifted high velocity outflow （200 -t-50 km s-1） from the star.

Measurements of the Ca II infrared triplet lines of young stellar objects

Equivalent widths and line widths of Ca II infrared triplet emission lines were measured in the high-resolution optical spectra of 39 young stellar objects.We found that the equivalent widths of the emission lines decrease with stellar evolution.It has often been claimed that strong chromospheric activity is generated by a dynamo process caused by fast rotation of the photosphere.However,we found no clear correlation between the strength of the Ca II lines and the stellar rotation velocity.Instead,we found that the objects with high mass accretion rates had stronger Ca II emission lines.This correlation supports the turbulent chromosphere model or the magnetic accretion theory for classical T Tauri stars.We also noticed that the equivalent widths of Ca II lines in transitional disk objects are one-tenth of those in classical T Tauri stars,even if the masses of the circumstellar disks are comparable.

Near-infrared studies of nova V5584 Sgr in the pre-maximum and early decline phase

We present near-infrared spectroscopic and photometric observations of nova V5584 Sgr taken during the first 12 d following its discovery on Oct. 26.439 UT2009. The evolution of the spectra is shown from the initial P Cygni phase to an emission line phase. The prominent carbon lines seen in the JHK spectra closely match those observed in an Fe II class nova outburst. The spectra show first-overtone CO bands in emission between 2.29-2.40 μm. By examining WISE and other publicly available data, we show that the nova underwent a pronounced dust formation phase between February- April 2010.

Evidence of Evolution in the Dense Cores in Massive Star Forming Regions

The excitation of H2O masers usually needs very high density gas,hence it can serve as a marker of dense gas in HⅡ region. We selected a sample of H2O maser sources from Plume et al. （four with, and four without detected CS（J = 7 - 6） emission）, and observed them in ^13CO（J=1-0） and C^18O （J=1-0）. C^18O （J=1-0） emission was detected only in three of the sources with detected CS（J=7-6） emission. An analysis combined with some data in the literature suggests that these dense cores may be located at different evolutionary stages. Multi-line observation study may provide us clues on the evolution of massive star forming regions and the massive stars themselves.

Simulation of the emission lines radiated from cataclysmic variables

Cataclysmic variables are special celestial bodies because they have particular light curves and spectra.The mechanisms for generating emission lines radiated from dwarf novae in their quiescent phases are studied.We assume that the incident radiation field which is emitted by a hot source（white dwarf and boundary layer）irradiates the gaseous layer evaporated from the accretion disk,and the emission lines are radiated from the gas.We model the fluxes of emission lines by using the photoionization code CLOUDY.Using this method,we input some reasonable parameters and get a series of simulated spectra.In order to find a simulated spectrum which is the best fit to an observed spectrum,we use a cross-correlation method to match them.After the calculation,we use the approximation that the parameters of the simulated spectrum can simulate the observed spectrum.Finally,we learn more about the physical conditions of the system.

The 6.7 keV Line Emission from the Stellar Flare of Algol

We present spectral analysis of Algol stellar flare data. The 2-day observation of Algol in our Galaxy was done by Suzaku Satellite. Algol binary system consists of two component stars that eclipse one another periodically. The stellar magnetic field activities and Roche Lobe overflow/mass transfer mechanisms during rapid rotation of the component stars generate an X-ray emission. The variation in brightness of the stellar flare from epoch to epoch provides useful information of stellar properties of the component stars. The atomic physics of the Kα line emission process in the vicinities of chromospherically active and X-ray flare stars, and binaries is well understood. The photo ionization/collisional excitation in the Algol’s corona produces 6.7 keV line emission. The accumulated spectra in X-ray Imaging Spectrometer (XIS) sensors fitted combined with bremsstrahlung model and Gaussian line show a strong fixed X-ray energy of 6.7 keV.

繁星树线图的完美匹配数

称一棵树T为繁星,如果它可以通过在星形树的悬挂点上添加一些悬挂边得到.给定两个正整数k和l满足k+l为偶数,令T_(k,l)表示由星形树S_(1,k)添加l条悬挂边而得到的所有繁星的集合.对任意的繁星T∈_(k,l),本文首先得到了其线图完美匹配数M(L(T))的表达式,然后通过引进一些变换,确定了M(L(T)),T∈_(k,l)的最小值和最大值.