A critique of supernova data analysis in cosmology

Observational astronomy has shown significant growth over the last decade and has made important contributions to cosmology. A major paradigm shift in cos- mology was brought about by observations of Type Ia supernovae. The notion that the universe is accelerating has led to several theoretical challenges. Unfortunately, although high-quality supernovae data-sets are being produced, their statistical anal- ysis leaves much to be desired. Instead of using the data to directly test the model, several studies ...     

朱文鑫《历代日食考》研究

用现代天文计算结果来全面研究整理中国古代日食记录,首推朱文鑫先生的<历代日食考>.他开拓的利用现代天文计算方法系统考察中国古代天象记录的研究,成为中国天文学史研究中的显学.介绍了<历代日食考>一书的内容和学术价值,比较了各个研究者对中国各代日食记录的统计,并对错误较多的西汉日食记录做了进一步的考证,以续朱先生言.分析指出,西汉日食记录的错误,许多是由另一条正确记录衍生出的.其错误的形态显示,原始记录只有年月,而日干支和所在宿度,是衍生错误已经发生之后加注的.     

天文学研究发展趋势分析--恒星与恒星系统

对在1981-2000年世界上所发表的和中国学者所发表的有关恒星与恒星系统的论文作统计发现：此期间世界上这一领域的发展较平稳，而我国的发展快速．这反映了改革开放后，我国基础学科研究大有进展．从各分支所占的比重和发展来看，我国在恒星与恒星系统的研究与世界同期有几乎相同的分布，因此总体上我国在这一领域的发展基本正常．当然有些分支发展较快，如有关超新星及其遗迹、星际介质和恒星形成区、化学丰度的研究等，这和一些较强的研究团组形成有关；在双星研究方面，我国则与世界发展一致，双星研究始终是恒星研究领域的重点；而在世界范围内较突出的关于银河系的研究，在我国却相对较弱．恒星和恒星系统这一研究领域20年的论文数统计显示，我国学者所发表的论文只占世界总论文数的1．3％，虽然在最后5年有大幅上升，但也只占2．0％，这与我国IAU会员数所占比例相比是偏少的．就世界整体而言，恒星领域的研究进展与整个天文学领域相比是较慢的，显然这与一批能做深空探测和高能波段观测的设备投入有关．因此，除了对恒星及恒星系统领域作统计分析外，对整个天文学领域各大分支作分析可能对制定今后我国天文学发展计划更有利。     

Analysis of Korean astronomical records with Chinese equatorial coordinates

The historical documents of ancient Korea contain abundant records on various astronomical phenomena. The historical documents of the Joseon dynasty contain observational values based on Chinese equatorial coordinate system (i.e., angular distances from the reference star of a lunar mansion and the North Pole). However, quantitative analysis of the observational values has not been carried out. In this study, we investigate the observational accuracy during the Joseon dynasty by comparing the astronomical records of Joseonwangjo Sillok (Annals of the Joseon Dynasty) and Seungjeongwon Ilgi (Daily Records of the Royal Secretariat) with modern astronomical calculations. Consequently, we find that the observational accuracy during the early Joseon dynasty was approximately 1°.2 and 0°.3 in the right ascension and declination, respectively. On the other hand, we find that the observational accuracy during the later Joseon dynasty was considerably poor. Observations of Halley's comet in 1759 were off by approximately 7° in declination. We believe that further investigation is required to verify the reason for this poor accuracy. Thus, we list the complete records used for this study in the appendix. We believe that these records also can contribute to modern studies on phenomena such as supernovae or Halley's comet. In conclusion, we believe that this study is useful for understanding ancient Korean astronomical records, even though we have considered a small number of astronomical events (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Gamma ray astronomy beyond 2001: What instruments for the newt challenges?

In spite of the recent successes of SIGMA, RXTE andCompton GRO, and the launch of INTEGRAL in 2001, a lot ofquestions will stay opened for the next decades in gamma-ray astronomy.In this context we have to think about future instrument concepts whichwill allow a new step in the understanding of high-energy phenomena atwork in many exciting objects: binary systems with compact objects,active galactic nuclei, supernovae and novae, gamma ray bursters...A short overview of these new types of instruments will be given.     

On the birtrate of galactic supernovae

The birthrate of galactic supernovae is estimated in three different ways:

1. on the basis of the historical record (eight events) the mean time interval between supernovae, τ, is considered to be in the range τ=60±40 yr;
2. on the basis of an approximate total of 120 supernovae events in hundreds of other galaxies, considered similar to our own, the interval obtained is in the range τ=70±50 yr; (iii) on the
3. on the basis of the 130 supernovae remnants in our own Galaxy, the interval is estimated to be in the range τ=80±30 yr. The three ranges overlap, and we suggest that 70±35 yr represents a more realistic estimate of the rate than some that have previously been made.

The galactic radio supernovae remnants, and their observed systematic brightness gradients perpendicular to the galactic plane, imply a scale height of about 200 pc for the remnant progenitors, and indicate that the galactic magnetic field's scale-height is about 300 pc. Long standing anomalies associated with (a) the young remnant AD 1006, (b) the galactic loops, and (c) faint remnants, are accounted for by the brightness gradient effect, providing independent, and firm, corroborating evidence for the fundamental validity of the remnant method of deducing the galactic supernova birthrate.     

The struve dynasty in the history of astronomy in Ukraine

The impact of the Struve astronomical dynasty on the development of astronomy in Ukraine in the 19th–20th centuries is studied. First of all, the role of F.G.W. Struve and O.V. Struve in the formation of astronomical research programs at the observatories at the Kharkiv, Kyiv, Odesa, and Mykolayiv, in equipping the observatories with instruments, in practical training of astronomers as well as in the organization of astronomy-geodetic expeditions (19th century). Particular attention is paid to the activity of L.O. Struve as a director of the Astronomical observatory of Kharkiv University and his works conducted together with G.A. Shajn and B.P. Gerasimovich (20th century) as well as to the impact of his scientific and public activity, including one he made as a President of IAC, on the development of astronomy in the Soviet Union and Ukraine. A range of important documents from the archives of Russian Academy of Sciences, Institute of astronomy and State Archive of Ukraine are cited. The article was translated by the authors.     

Using SNAP for Galactic &; extragalactic astronomy

SNAP, the SuperNova Acceleration Probe, is planned as a space-based telescope designed specifically to search for and monitor cosmological supernovae and weak lensing. In this paper we propose some other mission objectives which are of great importance in the fields of Galactic and extragalactic astronomy and which can be done as by-products with the same instrumentation and survey strategy as currently proposed for the main SNAP mission.     

中国古代常规日食记录的整理分析

收集并分析了公元前8世纪到公元15世纪的中国古代密集、简略而公式化的日食记录。基于这些记录整理成一个包括938条日食记录的计算机可读形式的“常规日食记录表”。该表给出每次记录的原日期、公历日期、当时首都、所属朝代以及一部分记录所载的进一步详情。对该表的构成作了介绍,并对这些历史记录进行了初步的分析和归纳。     

Astronomy in Antarctica

Antarctica provides a unique environment for astronomers to practice their trade. The cold, dry and stable air found above the high Antarctic plateau, as well as the pure ice below, offers new opportunities for the conduct of observational astronomy across both the photon and the particle spectrum. The summits of the Antarctic plateau provide the best seeing conditions, the darkest skies and the most transparent atmosphere of any earth-based observing site. Astronomical activities are now underway at four plateau sites: the Amundsen-Scott South Pole Station, Concordia Station at Dome C, Kunlun Station at Dome A and Fuji Station at Dome F, in addition to long duration ballooning from the coastal station of McMurdo, at stations run by the USA, France/Italy, China, Japan and the USA, respectively. The astronomy conducted from Antarctica includes optical, infrared, terahertz and sub-millimetre astronomy, measurements of cosmic microwave background anisotropies, solar astronomy, as well as high energy astrophysics involving the measurement of cosmic rays, gamma rays and neutrinos. Antarctica is also the richest source of meteorites on our planet. An extensive range of site testing measurements have been made over the high plateau sites. In this article, we summarise the facets of Antarctica that are driving developments in astronomy there, and review the results of the site testing experiments undertaken to quantify those characteristics of the Antarctic plateau relevant for astronomical observation. We also outline the historical development of the astronomy on the continent, and then review the principal scientific results to have emerged over the past three decades of activity in the discipline. These range from determination of the dominant frequencies of the 5 min solar oscillation in 1979 to the highest angular scale measurements yet made of the power spectrum of the CMBR anisotropies in 2010. They span through infrared views of the galactic ecology in star formation complexes in 1999, the first clear demonstration that the Universe was flat in 2000, the first detection of polarization in the CMBR in 2002, the mapping of the warm molecular gas across the ~ 300 pc extent of the Central Molecular Zone of our Galaxy in 2003, the measurement of cosmic neutrinos in 2005, and imaging of the thermal Sunyaev Zel’dovich effect in galaxy clusters in 2008. This review also discusses how science is conducted in Antarctica, and in particular the difficulties, as well as the advantages, faced by astronomers seeking to bring their experiments there. It also reviews some of the political issues that will be encountered, both at national and international level. Finally, the review discusses where Antarctic astronomy may be heading in the coming decade, in particular plans for infrared and terahertz astronomy, including the new facilities being considered for these wavebands at the high plateau stations.     

SPI cosmic radioactivity measurements in perspective

The ESA-Mission INTEGRAL (International Gamma-Ray Astrophysics Laboratory) is the next step in low-energy gamma-ray astronomy (up to 10 MeV) and will be launched in 2002. The spectrometer SPI—one of its two main instruments—is dedicated to high-resolution line spectroscopy (ΔE=2.5 keV FWHM at 1.3 MeV). SPI will concentrate on the study of lines from radioactive isotopes. A wealth of new information is expected from interstellar line emission with narrow line profiles, but exciting results are also expected from line profile measurements of individual line emitting objects such as supernovae, supernova remnants, and novae.     

Core-Collapse Supernovae and Gamma-Ray Bursts in TMT Era

Study of energetic cosmic explosions as a part of time domain astronomy is one of the key areas that could be pursued with upcoming Giant segmented optical-IR telescopes with a very large photon collecting area applying cutting edge technology. Existing 8–10 m class telescopes have been helpful to improve our knowledge about core-collapse supernovae, gamma-ray bursts and nature of their progenitors and explosion mechanisms. However, many aspects about these energetic cosmic explosions are still not well-understood and require much bigger telescopes and back-end instruments with high precision to address the evolution of massive stars and high-redshift Universe in more detail. In this presentation, possible thrust research areas towards core-collapse supernovae and gamma-ray bursts with the Thirty-Meter Telescope and back-end instruments are presented.     

The Chinese comet observation in AD 773 January

The strong ¹⁴C increase in the year AD 774/5 detected in one German and two Japanese trees was recently suggested to have been caused by an impact of a comet onto Earth and a deposition of large amounts of ¹⁴C into the atmosphere (Liu et al. 2014). The authors supported their claim using a report of a historic Chinese observation of a comet ostensibly colliding with Earth's atmosphere in AD 773 January. We show here that the Chinese text presented by those authors is not an original historic text, but that it is comprised of several different sources. Moreover, the translation presented in Liu et al. is misleading and inaccurate. We give the exact Chinese wordings and our English translations. According to the original sources, the Chinese observed a comet in mid January 773, but they report neither a collision nor a large coma, just a long tail. Also, there is no report in any of the source texts about “dust rain in the daytime” as claimed by Liu et al. (2014), but simply a normal dust storm. Ho (1962) reports sightings of this comet in China on AD 773 Jan 15 and/or 17 and in Japan on AD 773 Jan 20 (Ho 1962). At the relevant historic time, the Chinese held that comets were produced within the Earth's atmosphere, so that it would have been impossible for them to report a “collision” of a comet with Earth's atmosphere. The translation and conclusions made by Liu et al. (2014) are not supported by the historical record. Therefore, postulating a sudden increase in ¹⁴C in corals off the Chinese coast precisely in mid January 773 (Liu et al. 2014) is not justified given just the ²³⁰Th dating for AD 783 ± 14. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

夏商周断代工程及其天文学问题

《夏商周断代工程》由文献,考古,古文字,碳14测年和天文学待方面的专家联合攻关,致车于推进我国早期年代学研究的发展,天文学在五星聚合,三代大火,国外天象,仲康日食,夏小正,禹伐三苗,甲骨文天象,武王伐纣,天再旦,金文历谱,周代历法,计算中心等专题中起了主要或重要作用,天文方法确定的宾组月食,武王伐纣和天再旦年代被作为断代工程结论而采用,成为夏商周年的重要支撑点,铜器铭文中的朋相记录也是西周列王年代的重要依据。     

Secular Variation of Earth's Rotation: Inferred from the Chinese Ancient Shoushi Calendar (Ad 1281)

The Shoushi calendar (epoch of AD 1281, Yuan dynasty) is famous and very accurate in ancient China. It has evolved perfect and complete theoretical models of solar system objects, such as solar and lunar motions during that period. Almost every part of this work corresponds to the modern astronomical yearbooks. Compiled by native Chinese astronomers, it sums up through their studies many real observing results. The mathematical methods were adopted in this calendar before the foundation of Newton’s mechanical system. It is presented in this paper that the indirect system is also very useful to recover the real observing historical material. By selecting these calculating results, we may sum up the integral data of the secular variation of the Earth’s rotation from 1000 BC to AD 1500. This revised version was published online in July 2006 with corrections to the Cover Date.     

Are Type Ia Supernovae Standard Candles?

The use of standard candles for distance measurements is wide spread. Yet, we currently do not know a pure standard candle in astronomy. The concept of standard candles involves not only the secure establishment of a unique luminosity but also a clear observational distinction of the objects as a class. Even Type Ia supernovae, whose maximum luminosity shows amongst the smallest scatter known, need to be normalised to provide accurate distances. Without this normalisation the cosmological claims based on supernovae would not be possible. With a careful normalisation Type Ia supernovae are the best known distance indicators for cosmology to date. This is most easily shown by the small dispersion around the expansion line in the Hubble diagram. Problems with the empirical normalisation remain and a theoretical understanding of this normalisation is missing. This has direct ramifications on systematic uncertainties when deriving cosmological implications from Type Ia supernovae. Improving the understanding of supernova physics is now the prime task to sharpen this tool of observational cosmology. Once the explosion mechanism is revealed a serious discussion of possible evolutionary effects in Type Ia supernovae can start.     

The impact of new media on 20th century astronomy

This paper offers a few comments on the impact and changing sociology of astronomy information handling over the past century (especially its last third), drifting from individual measurements or records to catalogues and data centres, and moving recently from information hubs to distributed digital research facilities including the current projects of so‐called ‘virtual observatories’. After an introductory part and some notes on personal experience, the paper discusses data centres, methodologies, electronic publishing, as well problems and challenges inherited from the new media: fragility, security and ethics, not to forget the most important one, quality.     

Reminiscences of a Japanese Contemporary

It was in 1936 when a young Czech student of age 22 came to Japan through Siberia for participating in the solar eclipse expedition. Since then, he had visited us 13 times until 1993 (when he passed away). At each visit his lectures were vivid for us and had strong impact on the audience. Needless to say, it was the late Professor Zdeněk Kopal. In this brief presentation first I reveal my reminiscences of our common time in Manchester and Japan as a contemporary, and second I make some remarks on my activities for the Japanese Official Development Assistance (ODA) for astronomy in developing countries, in a similar way like Professor Kopal contributed in later years to the development of astronomy mainly in middle-east countries.     

Effects of Initial Conditions on Compressible Mixing in Supernova-Relevant Laboratory Experiments

In core-collapse supernovae, strong blast waves drive interfaces susceptible to Rayleigh–Taylor (RT), Richtmyer–Meshkov (RM), and Kelvin–Helmholtz (KH) instabilities. In addition, perturbation growth can result from material expansion in large-scale velocity gradients behind the shock front. Laser-driven experiments are designed to produce a strongly shocked interface whose evolution is a scaled version of the unstable hydrogen–helium interface in core-collapse supernovae such as SN 1987A. The ultimate goal of this research is to develop an understanding of the effect of hydrodynamic instabilities and the resulting transition to turbulence on supernovae observables that remain as yet unexplained. This paper represents a summary of recent results from a computational study of unstable systems driven by high Mach number shock and blast waves. For planar multimode systems, compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions (ICs) by allowing for memory of the initial conditions to be retained in the mix-width at all times. With higher-dimensional blast waves, divergence restores the properties necessary for establishment of the self-similar state, but achieving it requires very high initial characteristic mode number and high Mach number for the incident blast wave. Initial conditions predicted by some recent stellar calculations are incompatible with self-similarity.