四川省1:1万无图区域测图工程质量控制方法探讨

本文以四川实施的川西高原困难地区1︰1万无图区域测图项目为工程实例,针对川西高原地区1︰1万基础地理信息数据测制的技术路线和工艺流程,探讨了产品质量控制的流程、内容和方法,可为其他困难地区中等比例尺基础测绘产品的质量控制提供参考。     

Infall in massive clumps harboring bright infrared sources

Thirty massive clumps associated with bright infrared sources were observed to detect the infall signatures and characterize infall properties in the envelope of the massive clumps by APEX telescope in CO(4-3)and C17O(3-2)lines.Eighteen objects exhibit a"blue profile"in the CO(4-3)line with virial parameters less than 2,suggesting that global collapse is taking place in these massive clumps.The CO(4-3)lines were fitted via the two-layer model in order to obtain infall velocities and mass infall rates.Derived mass infall rates range from 10-3 to 10-1 M☉yr*(-1).A positive relationship between clump mass and infall rate appears to indicate that gravity plays a dominant role in the collapsing process.Higher luminosity clumps have a larger mass infall rate,implying that those clumps with higher mass infall rates possess a higher star formation rate.     

FUV and NIR size of the HI selected low surface brightness galaxies

How low surface brightness galaxies(LSBGs)form stars and assemble stellar mass is one of the most important questions related to understanding the LSBG population.We select a sample of 381 HI bright LSBGs with both far ultraviolet(FUV)and near infrared(NIR)observations to investigate the star formation rate(SFR)and stellar mass scales,and the growth mode.We measure the FUV and NIR radii of our sample,which represent the star-forming and stellar mass distribution scales respectively.We also compare the FUV and H band radius-stellar mass relation with archival data,to identify the SFR and stellar mass structure difference between the LSBG population and other galaxies.Since galaxy HI mass has a tight correlation with the HI radius,we can also compare the HI and FUV radii to understand the distribution of HI gas and star formation activities.Our results show that most of the HI selected LSBGs have extended star formation structure.The stellar mass distribution of LSBGs may have a similar structure to disk galaxies at the same stellar mass bins,but the star-forming activity of LSBGs happens at a larger radius than the high surface density galaxies,which may help to identify the LSBG sample from the wide-field deep u band image survey.The HI is also distributed at larger radii,implying a steeper(or not)Kennicutt-Schmidt relation for LSBGs.     

青海省地震前兆台网综述

青海省前兆台网承担本省前兆观测数据的汇集、处理、存储与报送任务。通过35年来的不断建设与完善,使得前兆项目密度增加,观测综合化水平得到大幅度提升,有效地提高了本省整体地震监测能力,在地震监测预报中发挥着重要作用。     

Effects of initial velocity on the sinking of ilmenite-bearing cumulates in the early lunar mantle:Insight from the theory of Rayleigh-Taylor instability

The early lunar mantle overturn,associated with the sinking of the dense ilmenite-bearing cumulate(IBC)crystallized at the shallow lunar mantle,provides satisfactory explanations for the origination of high-Ti basalt,the abnormally strong magnetic field between~3.9 and~3.6 Ga and the low-viscosity zone in the deep lunar mantle,but still poses a debate regarding the initial state of IBC in the early lunar mantle.If the sinking of IBC initiated before the end of lunar magma ocean crystallization,the solidified IBC can acquire a greater thickness and a higher initial velocity at the IBC-mantle boundary.The variation of initial velocity can affect the strain rate of IBC and,correspondingly,the dislocation creep components at the shallow lunar mantle.In this work,we analyze the effects of initial velocity on the dynamics of early lunar mantle by using the theory of Rayleigh-Taylor instability.To couple the effects of diffusion creep and dislocation creep for all major minerals in the lunar mantle,we exploit an improved Minimized Power Geometric(IMPG)model and isostress mixing model to characterize the upper limit and lower limit for the viscosity of the lunar mantle comprising four major minerals,i.e.olivine,orthopyroxene,clinopyroxene and ilmenite.The modeling results suggest that a high initial velocity,in any case,can shorten the onset time,tending to promote the early lunar mantle overturn even in a rheologically-strong lunar mantle.The effect of initial velocity on the overturn wavelength shows a strong dependence on the rheological mixing model.For the isostress mixing model,the increase of initial velocity tends to elongate the overturn wavelength.For the IMPG mixing model,the overturn wavelength is insensitive to the variation of initial velocity.As the actual lunar mantle rheology sandwiches between the rheologies predicted by isostress mixing model and IMPG model,it can be anticipated that the increase of initial velocity tends to elongate the overturn wavelength.In consideration of the importance of the initial velocity on the dynamics of early lunar mantle,future investigations should focus on the dynamics of the solid IBC in the solidifying lunar magma ocean.     

Resolution-dependent subsonic non-thermal line dispersion revealed by ALMA

We report here Atacama Large Millimeter/submillimeter Array(ALMA)N2H+(1-0)images of the Orion Molecular Cloud 2 and 3(OMC-2/3)with high angular resolution(3"or 1200 au)and high spatial dynamic range.Combining a dataset from the ALMA main array,Atacama Compact Array(ACA),Nobeyama 45-m Telescope and Very Large Array(VLA)(providing temperature measurement on matching scales),we find that most of the dense gas in OMC-2/3 is subsonic(σQNT/cs=0.62)with a mean line width(△v)of 0.39 kms-1 full width at half maximum(FWHM).This is markedly different from the majority of previous observations of massive star-forming regions.In contrast,line widths from the Nobeyama Telescope are transonic at 0.69 km s-1(σNT/cs=1.08).We demonstrated that the larger line widths obtained by the single-dish telescope arose from unresolved sub-structures within their respective beams.The dispersions from larger scalesσls(as traced by the Nobeyama Telescope)can be decomposed into three components such thatσls2=σss2+σbm2+σrd2,where small-scaleσss is the line dispersion of each ALMA beam,bulk motionσbm is dispersion between peak velocity of each ALMA beam andσrd is the residual dispersion.Such decomposition,though purely empirical,appears to be robust throughout our data cubes.Apparent supersonic line widths,commonly found in massive molecular clouds,are thus likely due to the effect of poor spatial resolution.The observed non-thermal line dispersion(sometimes referred to as’turbulence’)transits from supersonic to subsonic at~0.05 pc scales in the OMC-2/3 region.Such transition could be commonly found with sufficient spatial(not just angular)resolution,even in regions with massive young clusters,such as the Orion molecular clouds studied here.     

Pilot HI survey of Planck Galactic Cold Clumps with FAST

We present a pilot HI survey of 17 Planck Galactic Cold Clumps(PGCCs)with the Five-hundred-meter Aperture Spherical radio Telescope(FAST).HI Narrow Self-Absorption(HINSA)is an effective method to detect cold HI being mixed with molecular hydrogen H2 and improves our understanding of the atomic to molecular transition in the interstellar medium.HINSA was found in 58%PGCCs that we observed.The column density of HINSA was found to have an intermediate correlation with that of 13CO,following log(N(HINSA))=(0.52±0.26)log(N13CO)+(10±4.1).HI abundance relative to total hydrogen[HI]/[H]has an average value of 4.4×10-3,which is about 2.8 times of the average value of previous HINSA surveys toward molecular clouds.For clouds with total column density NH>5×1020 cm-2,an inverse correlation between HINSA abundance and total hydrogen column density is found,confirming the depletion of cold HI gas during molecular gas formation in more massive clouds.Nonthermal line width of 13CO is about 0-0.5 kms-1 larger than that of HINSA.One possible explanation of narrower non-thermal width of HINSA is that HINSA region is smaller than that of 13CO.Based on an analytic model of H2 formation and H2 dissociation by cosmic ray,we found the cloud ages to be within 106.7-107.0 yr for five sources.     

赛弗特星系恒星速度弥散度的测量

星系中心黑洞质量和核球恒星速度弥散度的紧密关系揭示出准确测量恒星速度弥散度对测定星系中心黑洞质量尤为重要.文中提供了一种利用SDSS(Sloan Digital SkySurvey)光谱测定速度弥散度及其不确定性的方法.通过对像素空间包含显著特征吸收线的4个不同谱区的拟合,得到准确测量恒星速度弥散度σ的光谱区域.文中4个拟合波段主要包含的吸收线为CaⅡK,MgⅠb三重线(波长5167.5,5172.7,5183.6(?))和CaT(CaⅡ三重线,波长8498.0,8542.1,8662.1(?)).不同区域结果表明,MgⅠb区由于受到铁族发射线影响,拟合的σ值偏低;CaⅡK线区谱线强度很弱,易受限于最小二乘法搜索算法;CaT+CaⅡK联合区得出的速度弥散度和只计算CaT区域的结果相当.利用该方法,测试了一个红移小于0.05的赛弗特星系样本,发现CaT区是测速度弥散度的最佳谱区.     

3C 345和3C 273的光变分析

用结构函数法,对两个经典的blazar 3C 273和3C 345的22 GHz、37 GHz和光学波段的数据进行了周期分析.结果显示,3C 273的周期性比较明显,22 GHz经分析存在7.0年和14.7年的周期,37 GHz存在7.2年和14.5年的周期,同时它的光学波段可能存在0.7年和8.7年的周期.3C 345的37 GHz存在比较明显的8.8年的周期,22 GHz和光学波段分别存在不太明显的9.3年和10.2年的周期.