探索我们的宇宙——2009国际天文年

[2009年1月10日,北京]从1609年到2009年,历史从伽利略第一次将望远镜用于天文观测至今已走过了四百年。这是望远镜光荣与梦想的四百年,是人类宇宙观不断发展的四百年,是人类的目光走向137亿光年的四百年。为纪念望远镜用于天文观测这一事件,联合国宣布将2009年定为国际天文年。这是一次天文学及其对社会、文化贡献的全球庆典。     

灰色拓扑理论在太阳黑子数年均值预测中的应用

简单介绍了灰色拓扑理论的原理,以1944—2008年各年的太阳黑子数年均值为基础,利用灰色拓扑预测方法建立了灰色拓扑预测模型群,并应用该模型群对第24、25和26太阳活动周自2009年到2039年共30 yr的太阳黑子数年均值进行了预测.预测结果表明,太阳黑子数极大年将可能出现在2014年、2023年和2033年,峰值分别为90、110和130,推测将在2017年、2025年和2039年达到极小值,极小值分别为20、20和10.     

利玛窦传入中国的西方宇宙观

利玛窦（意大利文：Matteo Ricci,1552年10月6日-1610年5月11日）,是耶稣会意大利传教士,1582年（明万历十年）来到澳门,次年利玛窦获准与罗明坚神父入居广东肇庆,1601年（明万历二十九年）抵达北京,1610年（明万历三十八年）去世。他在中国传教、生活了二十八年,将许多西方的天文学、地理学和数学知识传译到中国。     

让我们开始热身

还有不到一年,我们将进入世界天文年。那是伽利略发明天文望远镜之后的第400个年头。就像2005年的世界物理年,我们可以期待,2009年将成为全世界的天文嘉年华。虽然看起来2008年才刚刚开始,2009年尚未近在眼前,但实际上,现在我们是时候为拥抱世界天文年而开始热身了!     

联合国宣布2009年为国际天文年

在2007年12月20日的第62届联合国会员大会上,联合国宣布2009年为国际天文年。决议由伽利略的故乡意大利提交。2009年国际天文年由国际天文学联合会及联合国教科文组织共同主办。     

2009国际天文年官方指定产品大盘点

2009国际天文年虽然已经过去,但是这项有史以来在全球开展的规模最大的公众科普活动影响广泛,意义深远。因此,国际天文学联合会和国际天文年秘书处在2010年宣布进入“后国际天文年时代”。吸取国际天文年成功的经验,传承国际天文年的馈赠,继续在全世界展开一系列的公众天文科普活动。这里,让我们盘点一下2009国际天文年的官方指定产品。     

探索我们的宇宙——中国大陆地区2009国际天文年系列活动简介

当我们敲开2009年的大门,如同每个新年一样去迎接希望时,我们也满怀欣喜地盼来了国际天文年。400年沧桑,400年巨变,融入其中,何其幸哉!从2009年第一期开始,《天文爱好者》杂志作为国际天文年中国大陆地区惟一指定宣传杂志,将以专栏的形式全年刊登国际天文年最新动态,敬请关注!     

宇宙和谐 纵横谈——纪念开普勒发现行星运动定律400年

1609年是值得大书特书的一年。在那一年,伽利略率先使用望远镜观测星空,开创了望远镜天文学时代。400年后,联合国将2009年定为国际天文年。此外,在1609年,德国天文学家约翰尼斯·开普勒出版了《新天文学》（10年后又出版《宇宙和谐论》一书）,先后提出了著名的行星运动三定律,虽然这三大定律是零零散散地出现在他浩如烟海的著作里的,     

连续三年我国可见的壮观日食

如果天公作美的话,中国将在今后接连两年出现日全食（分别是2008年8月1日和2009年7月22日）,第三年看到日环食（2010年1月15日）。这是非常罕见的,也是上苍安排的天文盛宴。     

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.     

Hydrogen fluence in Genesis collectors: Implications for acceleration of solar wind and for solar metallicity

NASA's Genesis mission was flown to capture samples of the solar wind and return them to the Earth for measurement. The purpose of the mission was to determine the chemical and isotopic composition of the Sun with significantly better precision than known before. Abundance data are now available for noble gases, magnesium, sodium, calcium, potassium, aluminum, chromium, iron, and other elements. Here, we report abundance data for hydrogen in four solar wind regimes collected by the Genesis mission (bulk solar wind, interstream low‐energy wind, coronal hole high‐energy wind, and coronal mass ejections). The mission was not designed to collect hydrogen, and in order to measure it, we had to overcome a variety of technical problems, as described herein. The relative hydrogen fluences among the four regimes should be accurate to better than ±5–6%, and the absolute fluences should be accurate to ±10%. We use the data to investigate elemental fractionations due to the first ionization potential during acceleration of the solar wind. We also use our data, combined with regime data for neon and argon, to estimate the solar neon and argon abundances, elements that cannot be measured spectroscopically in the solar photosphere.     

DBSCAN Clustering Algorithm for the Detection of Nearby Open Clusters Based on Gaia-DR2two

In this paper, we attempt to use the DBSCAN (Density-Based Spatial Clustering of Applications with Noise) clustering algorithm to detect nearby open clusters based on the Gaia Data Release 2 (Gaia-DR2). We select 594284 stars (within a distance of 100 pc to the Sun) from the Gaia-DR2 catalog, and construct a five-dimensional phase space (three-dimensional spatial position and two-dimensional proper motion) in order to obtain reliable cluster members. At the data preprocessing stage, we normalize each dimension of data to the [0, 1] interval in order to avoid the effect of inconsistent units. Then, we use the k-dist graphs to determine the input parameters of the DBSCAN Algorithm. Finally, we obtain 133 reliable members using the DBSCAN algorithm, which correspond to two open clusters—Hyades and Coma. According to these cluster members, the distances to the Hyades and Coma clusters are determined to be (6.5 ± 0.3) pc and (4.9 ± 0.4) pc, respectively.     

Frozen orbits at high eccentricity and inclination: application to Mercury orbiter

We hereby study the stability of a massless probe orbiting around an oblate central body (planet or planetary satellite) perturbed by a third body, assumed to lay in the equatorial plane (Sun or Jupiter for example) using a Hamiltonian formalism. We are able to determine, in the parameters space, the location of the frozen orbits, namely orbits whose orbital elements remain constant on average, to characterize their stability/unstability and to compute the periods of the equilibria. The proposed theory is general enough, to be applied to a wide range of probes around planet or natural planetary satellites. The BepiColombo mission is used to motivate our analysis and to provide specific numerical data to check our analytical results. Finally, we also bring to the light that the coefficient J ₂ is able to protect against the increasing of the eccentricity due to the Kozai-Lidov effect and the coefficient J ₃ determines a shift of the equilibria.     

SILENT: Spectrograph simulation and emulation tool

A software tool which was designed to compute basic optical parameters of spectrographs is presented. The idea is to find a first layout of the spectrograph by focusing on the science goal to which the instrument needs to be adapted. We focus on systems used in astrophysical instrumentation. These include classical, 3D and echelle spectrographs. The code also computes efficiencies of the specified systems, expected signal-to-noise ratios, layout of the spectral orders on the detector, etc. Furthermore, a complete image seen by the detector can be simulated. This artificial data are used to compare the performance of different designs and to test data reduction pipelines, before the system is being physically build. Some additional tools are implemented to characterise special optical devices, for example the telescope-spectrograph-interface and to support the design process. Hence, SILENT is a pre-design tool to determine the required optical paraxial parameters of the system to meet the science application.     

Fitting the integrated spectral energy distributions of galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details of dust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.     

All you ever wanted to know about optical long baseline stellar interferometry, but were too shy to ask your adviser

I try to present a small view of the properties and issues related to astronomical interferometry observations. I recall a bit of history of the technique, give some basic assessments to the principle of interferometry, and finally, describe physical processes and limitations that affect optical long baseline interferometry and which are, in general, very useful for everyday work. Therefore, this text is not intended to perform strong demonstrations and show accurate results, but rather to transmit the general “feeling” one needs to have to not be destabilised by the first contact to real world interferometry.     

Decametric radio spectra and positions during the flare of August 28, 1966: 1522 UT

During a period of intense decametric continuum arising near the center of the sun, there occurred additional very strong emission closely associated with the flare beginning at 1522 UT on August 28, 1966. Owing to strong ionospheric absorption from about 1527 UT on, which eliminated telecommunications interference, the frequency range over which the flare-associated emission appears is unusually large, from the upper limit of the spectrograph, 41 MHz, to about 11 MHz, where external reflection cuts off the solar signals. Strong bursts of Type III (fast drift) occur from 1527 to 1531 UT, and a complex Type II (slow drift) from 1532 to 1547 UT. As the Type-II burst progresses at frequencies from 15 to 25 MHz, Northward position shifts of many solar radii probably take place; at higher frequencies the burst moves in a complicated pattern through a much narrower range of distances to the North of the sun. Type-IV emission, from 1540 UT on, moves a large distance to the sun's North, and then, after 1600 UT, returns to a stable position quite close to the sun.     

Digitization and Scientific Exploitation of the Italian and Vatican Astronomical Plate Archives

There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes, and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in the course of this project have been already applied successfully to plates taken by other Observatories, for instance at Byurakan and at Hamburg.     

Precise measurement of the solar gravitational red shift

We present the concept and the status of a multi-year project based on a new method to measure the Gravitational Red Shift of the Solar Spectrum with high precision. This project is aimed to conduct experimental verifications of the effect that the Einstein theory of General Relativity predicts for the frequencies of the Fraunhofer lines, that is, the light spectrum emitted by the Sun in its strong gravitational field. Previous determinations of such effect is limited to a precision of 2%. In order to discriminate between classical and relativistic explanations, we need to be sensitive to one part per million of the predicted effect. We have developed a new powerful technique, the Magneto-Optical Filter, that is able to provide far better precision and, for the future, possible space instrumentations able to extend our test to the second-order effect of the relativistic equivalence principle, never done before. The present paper is intended to describe the instrumentation, the procedure and the first encouraging results.     

Solar diameter(s)

Because of the renewed attention now paid to the solar diameter, its variations from equator to pole, or its secular or long-period changes, the question: what is a solar diameter? is not meaningless. Two kinds of definitions may be given: either astrophysical, each one relating to a specific physical parameter, or observational, relating to a given quantity to be measured. Only the second kind is directly accessible, and astrophysical definitions should be linked to these quantities, once they are determined with the highest possible accuracy. In practice, all the programs under way refer to the point of the limb where the brightness gradient is maximum, or to a higher order approximation of the shape of the profile. Two of them are compared: the Pic-du-Midi experiment, using fast scans of the limb to define the inflection point after a correction for the blurring effect of the atmosphere, and the SCLERA experiment, using the algorithm called FFTD to eliminate this correction. The advantage of a fast scan is emphasized, and the remark is formulated that, once the signal is digitized and stored, FFTD or any processing of it can be performed. In collecting day-long one-limb scans to calibrate the blurring correction, the authors have found fluctuations of the maximum brightness gradient which provide a new entry to the field of solar oscillations.