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1.
In the beginning Copernicus' system of the world did not have empirical confirmation. In this situation, Kepler's research, as well as the astronomical observations with the telescope, invented in 1608, played a decisive role. Under the assumption of the central position of the Sun, Kepler discovered the elliptical orbital motion of the planets as a base of the computation of noticeably improved ephemerides. The first telescopic observations – Jupiter's moons, phases of Venus, sunspots, surface features of the moon, gave important arguments for Copernicus' system. Galilei was one of the first who used the telescope for astronomical research (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

2.
Yearly calendars were a mass‐produced article in early modern times and had an enormous importance in everyday life. Besides a first part, the Calendarium with the monthly tables, they contain a second part, the astrological Prognosticum. At first, the two parts were sold separately. In the second half of the 17th century, the parts were designed as a unity and sold together. The calendars in quart format contain texts which are so interesting that historical research should give them more consideration. Such a text is found, e.g., in the second part of the calendar for 1611, written by Paul Nagel, astronomer and rector of the school in Torgau. Nagel informs about Galilei's discoveries with the telescope. The (Latin) text was written in August 1610. This text is presented and put into perspective in the scientific debates of the time about the telescope as a new invention with consequences to philosophy (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

3.
The first radio astronomical investigations in the Lebedev Physical Institute are described. Some details of the large radio telescopes construction in Pushchino Radio Astronomy Observatory as well as the most significant scientific results obtained with them are quoted in the paper, too. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

4.
The authors’ individual work on the inclination functions over a period of more than 30 years has led to the need for a joint paper. Intervening papers by other authors have demonstrated misunderstandings needing to be corrected, in particular concerning the key recurrence relation published by the present first author in 1971. This relation is remarkably stable, though this has not always been recognized. The real source of error with the specific functions that are involved in the recurrence relation arises from the possibilities for underflow (as well as overflow) in the computation. The problem exists even with normalized versions of the functions, and is carefully addressed. Very important, for both academic and practical reasons, is a general invariance relation that had been found earlier by the second author, for which a proof is given here for the first time. Some numerical results from our new (and highly efficient) procedure for computing the inclination functions are tabulated, and comparisons made with the results of other authors. Finally, Fortran code for an optimized implementation of this procedure is in supplementary material. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

5.
We attempt to throw light upon the poorly known astronomical dynasty of Knorre and describe its contribution to astronomy. The founder of the dynasty, Ernst Christoph Friedrich Knorre (1759–1810), was born in Germany in 1759, and since 1802 he was a Professor of Mathematics at the Tartu University, and observer at its temporary observatory. He determined the first coordinates of Tartu by stellar observations. Karl Friedrich Knorre (1801–1883) was the first director of the Naval Observatory in Nikolaev since the age of 20, provided the Black Sea navy with accurate time and charts, trained mariners in astronomical navigation, and certified navigation equipment. He compiled star maps and catalogues, and determined positions of comets and planets. He also participated in Bessel's project of the Academic Star Charts, and was responsible for Hora 4, published by the Berlin Academy of Sciences. This sheet permitted to discover two minor planets, Astraea and Flora. Viktor Knorre (1840–1919) was born in Nikolaev. In 1862 he left for Berlin to study astronomy. After defending his thesis for a doctor's degree, he went to Pulkovo as an astronomical calculator in 1867. Since 1873 Viktor worked as an observer of the Berlin Observatory Fraunhofer refractor. His main research focussed on minor planets, comets and binary stars. He discovered the minor planets Koronis, Oenone, Hypatia and Penthesilea. Viktor Knorre also worked on improving astronomical instrumentation, e.g. the Knorre & Heele equatorial telescope mounting (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

6.
A comparative study of simulated air shower longitudinal profiles is presented. An appropriate thinning level for the calculations is first determined empirically. High statistics results are then provided, over a wide energy range (1014.0–1020.5 eV), for proton and iron primaries, using four combinations of the and program frameworks, and the SIBYLL and QGSjet high energy hadronic interaction models. These results are compared to existing experimental data. The way in which the first interaction controls Xmax is investigated, as is the distribution of Xmax.  相似文献   

7.
We have searched for nearby dwarf galaxies in 27 northern groups with characteristic distances 8–15 Mpc based on the Second Palomar Sky Survey prints. In a total area of about 2000 square degrees, we have found 90 low-surface-brightness objects, more than 60% of which are absent from known catalogs and lists. We have classified most of these objects (～80%) as irregular dwarf systems. The first 21-cm line observations of the new objects with the 100-m Effelsberg radio telescope showed that the typical linear diameters (1–2 kpc), internal motions (～30 km s?1), and hydrogen masses (～2 × 107 M ⊙) of the new galaxies correspond to those expected for the dwarf population of nearby groups.  相似文献   

8.
In this paper, we determine series of horizontally critical symmetric periodic orbits of the six basic families, f,g,h,i,l,m, of the photogravitational restricted three-body problem, and computetheir vertical stability. We restrict our study in the case where only the first primary is radiating, namely q 1≠1 andq 2=1. We also compare our results with those of Hénon and Guyot (1970) so as to study the effect of radiation to this kind of orbits. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

9.
This article gives a brief overview of 400 years of research in the field of novae and related stars. Important objects, first applications of various observing techniques, and early ideas of the interpretation of phenomena are listed. Also, the historical evolution of the classification of novae and related stars (supernovae, dwarf novae), as well as their use as distance indicators is discussed (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

10.
Numerical simulations are made within the framework of the plane restricted three-body problem, in order to find out if stable orbits for planets around one of the two components in double stars can exist. For any given set of initial parameters (the mass ratio of the two stars and the eccentricity of their orbit around each other), the phase-space of initial positions and velocities is systematically explored.In previous works, systematic exploration of the circular model as well as studies of more realistic (elliptic) cases such as Sun-Jupiter and the nearby Centauri and Sirius systems, large stable planetary orbits were found to exist around both components of the binary, up to distances from each star of the order or more than half the binary's periastron separation.The first results presented here for the Coronae Borealis system confirm the previous studies.  相似文献   

11.
As galaxy surveys become larger and more complex, keeping track of the completeness, magnitude limit and other survey parameters as a function of direction on the sky becomes an increasingly challenging computational task. For example, typical angular masks of the Sloan Digital Sky Survey contain about   N = 300 000  distinct spherical polygons. Managing masks with such large numbers of polygons becomes intractably slow, particularly for tasks that run in time     with a naive algorithm, such as finding which polygons overlap each other. Here we present a 'divide-and-conquer' solution to this challenge: we first split the angular mask into pre-defined regions called 'pixels', such that each polygon is in only one pixel, and then perform further computations, such as checking for overlap, on the polygons within each pixel separately. This reduces     tasks to     , and also reduces the important task of determining in which polygon(s) a point on the sky lies from     to     , resulting in significant computational speedup. Additionally, we present a method to efficiently convert any angular mask to and from the popular healpix format. This method can be generically applied to convert to and from any desired spherical pixelization. We have implemented these techniques in a new version of the mangle software package, which is freely available at http://space.mit.edu/home/tegmark/mangle/ , along with complete documentation and example applications. These new methods should prove quite useful to the astronomical community, and since mangle is a generic tool for managing angular masks on a sphere, it has the potential to benefit terrestrial mapmaking applications as well.  相似文献   

12.
Clusters of galaxies offer a robust test bed for probing the nature of dark matter that is insensitive to the assumption of the gravity theories. Both Modified Newtonian Dynamics (MOND) and General Relativity (GR) would require similar amounts of non-baryonic matter in clusters as MOND boosts the gravity only mildly on cluster scales. Gravitational lensing allows us to estimate the enclosed mass in clusters on small (∼20–50 kpc) and large (∼several 100 kpc) scales independent of the assumptions of equilibrium. Here, we show for the first time that a combination of strong and weak gravitational lensing effects can set interesting limits on the phase-space density of dark matter in the centres of clusters. The phase-space densities derived from lensing observations are inconsistent with neutrino masses ranging from 2–7 eV, and hence do not support the 2 eV-range particles required by MOND. To survive, the most plausible modification for MOND may be an additional degree of dynamical freedom in a covariant incarnation.  相似文献   

13.
Hoyt & Schatten (1998) claim that Simon Marius would have observed the sun from 1617 Jun 7 to 1618 Dec 31 (Gregorian calendar) all days, except three short gaps in 1618, but would never have detected a sunspot – based on a quotation from Marius in Wolf (1857), but mis‐interpreted by Hoyt & Schatten. Marius himself specified in early 1619 that for one and a half year... rather few or more often no spots could be detected... which was never observed before (Marius 1619). The generic statement by Marius can be interpreted such that the active day fraction was below 0.5 (but not zero) from fall 1617 to spring 1619 and that it was 1 before fall 1617 (since August 1611). Hoyt & Schatten cite Zinner (1952), who referred to Zinner (1942), where observing dates by Marius since 1611 are given but which were not used by Hoyt & Schatten. We present all relevant texts from Marius where he clearly stated that he observed many spots in different form on and since 1611 Aug 3 (Julian) = Aug 13 (Greg.) (on the first day together with Ahasverus Schmidnerus); 14 spots on 1612 May 30 (Julian) = Jun 9 (Greg.), which is consistent with drawings by Galilei and Jungius for that day, the latter is shown here for the first time; at least one spot on 1611 Oct 3 and/or 11 (Julian), i.e. Oct 13 and/or 21 (Greg.), when he changed his sunspot observing technique; he also mentioned that he has drawn sunspots for 1611 Nov 17 (Julian) = Nov 27 (Greg.); in addition to those clearly datable detections, there is evidence in the texts for regular observations. For all the information that can be compared to other observers, the data from Marius could be confirmed, so that his texts are highly credible. We also correct several shortcomings or apparent errors in the database by Hoyt & Schatten (1998) regarding 1612 (Harriot), 1615 (Saxonius, Tard´e), 1616 (Tard´e), 1617–1619 (Marius, Riccioli/Argoli), and Malapert (for 1618, 1620, and 1621). Furthermore, Schmidnerus, Cysat, David & Johann Fabricius, Tanner, Perovius, Argoli, and Wely are not mentioned as observers for 1611, 1612, 1618, 1620, and 1621 in Hoyt & Schatten. Marius and Schmidnerus are among the earliest datable telescopic sunspot observers (1611 Aug 3, Julian), namely after Harriot, the two Fabricius (father and son), Scheiner, and Cysat. Sunspots records by Malapert from 1618 to 1621 show that the last low‐latitude spot was seen in Dec 1620, while the first high‐latitude spots were noticed in June and Oct 1620, so that the Schwabe cycle turnover (minimum) took place around that time, which is also consistent with the sunspot trend mentioned by Marius and with naked‐eye spots and likely true aurorae. We consider discrepancies in the Hoyt & Schatten (1998) systematics, we compile the active day fractions for the 1610s, and we critically discuss very recent publications on Marius which include the following Maunder Minimum. Our work should be seen as a call to go back to the historical sources. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

14.
We present an inventory ofthe Carte du Ciel (CdC) plates stored in the Astrophysical Institute Potsdam. The Potsdam CdC zone (+32° to +39°) was divided into 1232 areas and about 2200 plates from the first and second epochs were obtained within the framework of the CdC project. At present, only 977 plates (45% of all) are stored in AIP, the others got lost during the Second World War. The plates for the first epoch measurements had been obtained during the period 1893 May– 1900 February. The plates for the second epoch (1913 August–1924 February) can be separated into two time intervals according to the observer and the observing method used: from 1913 August till 1914 July, and from 1916 February to 1924 February. The present work aims to provide online access to the plate information, given in the plate catalogue and is the first step to online access to the plate images digitized with flatbed scanners.  相似文献   

15.
We have recently digitized and partially reanalyzed the historic bolide infrasonic database. These 10 events were originally detected by the U.S. Air Force Technical Applications Center (AFTAC) from ∼1960 to 1974. In this paper we present the first preliminary reanalysis results for two of the 10 bolide events, namely the Revelstoke bolide of 3/31/1965 as well as the Prince Edward Islands (P.E.I). S. African bolide of 8/03/1963, which were among the largest bolides detected during this time period. These bolides have been investigated initially since they are most likely to have had a significant effect on the computed global influx rate of ReVelle (Global Infrasonic Monitoring of Large Bolides, pp 483–490, 2001) as indicated in Brown et al. (Nature, 420:314–316, 2002). We are in the process of recomputing all relevant infrasonic propagation quantities such as plane wave back azimuth, signal velocities, power spectra, spectrograms, as well as energy estimates using multiple techniques. In a future paper we will present a complete digital reanalysis of the AFTAC bolide infrasonic data and its final resulting global bolide influx implications.  相似文献   

16.
Despite the fact that microbial cells are unlikely to be found in the Martian soil in the near future, this paper is written on the assumption that some of the seasonally varying concentration of Martian methane is due to ongoing methanogenesis. It is first pointed out that life might have arisen on Mars first and been transported to Earth later. A case is made that an icy origin of life is more likely than a hot origin, especially if biomolecules take advantage of the high encounter rates and stability against hydrolysis, and that microorganisms feed on the ions that comprise eutectic solutions in ice. Although certain difficulties are avoided if RNA and DNA grow while adsorbed on clay grains, double strand-breaks of microbial DNA due to alpha radioactivity are a far greater threat to microbial survival on clay or other rock types than in ice. Developing a relation between the rate of microbial metabolism in ice and the experimentally determined rate of production of trapped gases of microbial origin, one can estimate the concentration of methanogens that could account for the methane production rate as a function of temperature of their habitat. The result, of order 1 cell cm−3 in the Martian subsurface, seems an attainable goal provided samples are taken from at least 1 or 2 m below the hostile surface of Mars. Instruments on NASA’s 2011 Mars Science Lab will measure stable isotopes for methane, water, and carbon dioxide, which on Earth served to distinguish abiotic, thermogenic, and microbial origins. Future measurements of chirality of biomolecules might also provide evidence for Martian life.  相似文献   

17.
This paper presents a comparison of the predictions for the two- and three-point correlation functions of density fluctuations, ξ and ζ , in gravitational perturbation theory (PT) against large cold dark matter (CDM) simulations. This comparison is made possible for the first time on large weakly non-linear scales (>10  h −1 Mpc) thanks to the development of a new algorithm for estimating correlation functions for millions of points in only a few minutes. Previous studies in the literature comparing the PT predictions of the three-point statistics with simulations have focused mostly on Fourier space, angular space or smoothed fields. Results in configuration space, such as those presented here, were limited to small scales where leading-order PT gives a poor approximation. Here we also propose and apply a method for separating the first-order and subsequent contributions to PT by combining different output times from the evolved simulations. We find that in all cases there is a regime where simulations do reproduce the leading-order (tree-level) predictions of PT for the reduced three-point function   Q 3∼ ζ / ξ 2  . For steeply decreasing correlations (such as the standard CDM model) deviations from the tree-level results are important even at relatively large scales, ≃20 Mpc  h −1. On larger scales ξ goes to zero and the results are dominated by sampling errors. In more realistic models (such as the ΛCDM cosmology) deviations from the leading-order PT become important at smaller scales   r ≃10 Mpc  h -1  , although this depends on the particular three-point configuration. We characterize the range of validity of this agreement and show the behaviour of the next-order (one-loop) corrections.  相似文献   

18.
使用像管摄谱仪和Reticon探测器获得了食双星AA UMa的高色散和高时间分辨率的光谱,并用交叉相关函数法测得其视向速度。从光谱特征来看,AA UMa是一对W UMa型食双星。本文首次给出了AA UMa的分光轨道解。在圆周运动的假设下,轨道根数测定为:P=0.468171天;T_0(相应于测光主极小时刻)=HJD2,446,520.4448;K_1=124.0公里/秒;K_2=227.7公里/秒。像其他一些使用本方法获得分光轨道解的食双星一样,AA UMa系统的质心速度没有能够唯一地确定,但是V_0=-34.8公里/秒可能是一个较好的估值。根据分光轨道根数,本文给出了新的测光历元公式:HJD Min I=2,446,520,4448(8)+0.468171(48)·E。AA UMa两子星的光谱型十分相似,与变星总表(GCVS)所列的GoV相一致。两子星的质量比为0.54,星等差为0.36(～B)  相似文献   

19.
Ejecta from Saturn's moon Hyperion are subject to powerful perturbations from nearby Titan, which control their ultimate fate. We have performed numerical integrations to simulate a simplified system consisting of Saturn (including optical flattening as well as dynamical oblateness), its main ring system (treated as a massless flat annulus), the moons Tethys, Dione, Titan, Hyperion, and Iapetus, and the Sun (treated simply as a massive satellite). At several different points in Hyperion's orbit, 1050 massless particles, more or less evenly distributed over latitude and longitude, were ejected radially outward from 1 km above Hyperion's mean radius at speeds 10% faster than escape speed from Hyperion. Most of these particles were removed within the first few thousand years, but ∼3% of them survived the entire 100,000-year duration of the simulations. Ejecta from Hyperion are much more widely scattered than previously thought, and can cross the orbits of all of Saturn's satellites. About 9% of all the particles escaped from the saturnian system, but Titan accreted ∼78% of the total, while Hyperion reaccreted only ∼5%. This low efficiency of reaccretion may help to account for Hyperion's small size and rugged shape. Only ∼1% of all the particles hit other satellites, and another ∼1% impacted Saturn itself, while ∼3% of them struck its main rings. The high proportion of impacts into Saturn's rings is surprising; these collisions show a broad decline in impact speed with time, suggesting that Hyperion ejecta gradually spread inwards. Additional simulations were used to investigate the dependence of ejecta evolution on launch speed, the mass of Hyperion, and the presence of the Sun. In general, the wide distribution of ejecta from Hyperion suggests that it does contribute to “Population II” craters on the inner satellites of Saturn. Ejecta which escape from a satellite into temporary orbit about its planet, but later reimpact into the same moon or another one produce “poltorary” impacts, intermediate in character between primary and secondary impacts. It may be possible to distinguish poltorary craters from primary and secondary craters on the basis of morphology.  相似文献   

20.
Summary. The maximum mass of neutron stars plays an important role in determining the end point of the evolution of massive stars. As the number of stellar mass black holes in binary x-ray sources grows, and as the mass spectrum of the black holes emerges, the value of the maximum mass of neutron stars has acquired great significance. Although it is now more than sixty years since the first attempt by Oppenheimer and Volkoff, no definitive answer can be given. This review will attempt to outline the main difficulties, both conceptual as well as technical, that stand in the way of a reliable estimate of the maximum mass. We shall also highlight how laboratory experiments, as well as astronomical observations, may help to clarify the true nature of the interior of neutron stars. Received 26 November 2001 / Published online 22 April 2002  相似文献   

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