bluuebunny/crossref_metadata_2025_split huggingface dataset:
The instantaneous position and diameter of short duration bursts of solar radio emission
Authors: Högbom J. A. 
Published: July 2016

It is known that the regions responsible for solar noise storms are associated with visible sunspot groups and that the diameter of such radio sources is not less than 7 minutes of arc at a wavelength of 3.7 m. Little, however, is known of the size and location of the individual short-lived bursts (duration ~1 second). Two interferometric systems have been set up at 3.7 m to measure these quantities, and some preliminary results have been obtained:(a) The diameters of single bursts. To measure the diameters of individual bursts an interferometer of spacing 270λ was connected to three receivers. Receivers 2 and 3 gave records corresponding to total power interferometers in antiphase, while receiver 1 was arranged as a phase-switching interferometer in quadrature with the other two. From the relative sizes of an individual burst on the three records it is possible to determine the burst intensity, its angular size and position in one coordinate. Measurements carried out during a noise storm on 1958 March 21 gave an angular diameter of 6 ± 1 minutes of arc for about 25 individual bursts.(b) The location of single bursts in two dimensions. In order to determine the instantaneous position of individual bursts, two phase-switching interferometers of spacing 135λ were aligned in E-W and N-S directions. A third aerial was used with a total power receiver to measure the burst intensity. Preliminary results indicate that the positions of the individual bursts during a noise storm show a scatter of less than 3 minutes of arc.
New data on the solar supercorona
Authors: Vitkevich V. V. 
Published: July 2016

1. This paper reports on the results of the investigation of the outermost regions of the solar corona (which for brevity I shall call the supercorona) that have been obtained during recent years.Seven years ago, in 1951, a new method of observation was published in Doklady of the Academy of Sciences of the U.S.S.R. The idea of the method, which at the present time is well known, is that the radio emission of the Crab nebula is received at the time when the source is covered by the solar corona. This original eclipse takes place yearly in the middle of June.By receiving the radio waves that pass through the solar corona regions, we can estimate the effects of attenuation, scattering and refraction and reach some conclusions about the structure of the supercorona.
A luminosity discriminant in the infrared spectrum of late-type stars
Authors: Whitford A. E. 
Published: July 2016

The sensitivity of the lines of the Na1 doubletλ8183–8195 (32P− 32D) to luminosity, previously noted by Sharpless (1) has been studied on spectra of MK standard stars ranging from K0III to M3III and from K2V to M6V. The prime focus spectrograph of the 120 inch telescope gave the same dispersion used by Sharpless, 200Å/mm. The objective was to test the suitability of the lines as an indicator of the contribution of dwarf stars to the total light of galaxies. Spinrad (2) and Deutsch (3) have noted that the sodium D lines are stronger in the spectrum of massive galaxies than would be expected if the dominant contribution to the total light came from giant stars. The advantages of the infrared sodium doublet are:1. In a composite source, cool stars become a progressively more important contributor to the total radiation at longer wavelengths.
The progress of multicolour photometry
Authors: Walraven Th. 
Published: July 2016

After the introduction of photography as a tool in astronomy, the spectroscopists were the first to open a new field of exploration, i.e. the study of the physical nature of stars.They gradually split up in different groups. The coudé spectroscopists studied spectra of high resolution and with much tedious work measured the equivalent width of each line and the shape of the line profiles. This work is restricted to the brightest stars.
Desiderata in connection by the calibration of the MK-system
Authors: Schmidt-Kaler Th. 
Published: July 2016

This is only an informal remark about some difficulties I am worrying about.I have tried to recalibrate the MK system in terms of intrinsic colour (B–V)0and absolute magnitudeMv. The procedures used have been described in a review article by Voigt (Mitt. Astr. Ges.1963, p. 25–35), and the results for stars of the luminosity classes Ia-O,I and II have been given also in Blaauw's article on the calibration of luminosity criteria in vol. III (Basic Astronomical Data, p. 401) ofStars and Stellar Systems.
Broadband Structure in the Interstellar Extinction Curve
Authors: Hayes D. S. , Mavko G. E. , Radick R. R. , Rex K. H. , Greenberg J. M. 
Published: July 2016

We have analysed observations of the interstellar extinction in the range 3400 Å–l 1000 Å. The observations have high photometric accuracy and wavelength resolution, and allow a detailed examination of broadband structure as well as the general shape of the wavelength dependence of the extinction curve. The broadband structure has a characteristic size of several hundred ångströms, and may be as important as the diffuse bands in indicating the physical nature of the grains.We describe our preliminary theoretical interpretation of this broadband structure, and the new observation which it predicts.
What Do We Know About Algol?
Authors: Söderhjelm S. 
Published: July 2016

A comprehensive analysis of previously published observations of Algol has been submitted to Astronomy&Astrophysics under the title “Geometry and Dynamics of the Algol System”. The main results can be summarized as follows:The masses of the three components are mA = 3.6±0.1, mB=0.79±0.01, mC=1.6±0.1 solar masses.The orbit of Algol C is co-planar with the AB-orbit within some 3°, but polarimetry of the eclipsing pair indicates that the senses of revolution are opposite.The close orbit is circular, thus the 32 year period in the times of minima can not be explained by apsidal motion.
Evidence for a 6 Year Periodicity in X Persei
Authors: Dorren J. D. , Guinan E. F. 
Published: July 2016

Intermediate and narrow-band photoelectric observations obtained at Biruni and Villanova Observatories from 1977 to the present, when combined with previous data, strongly suggest that light increases of about 0.5 mag occur at 6 year intervals. Possible explanations are considered.The X-ray pulsator X Persei (4U 0352+30) is an intriguing object at both X-ray and optical wavelengths. From the X-ray data a period of 13.9 minutes now appears well-established, but early suggestions of a 22.4 hour periodicity remain unconfirmed (White et al.,1976, Becker et al., 1979). The nature of the X-ray emission is unusual; the source is about 3 orders of magnitude weaker than other X-ray binary pulsars, and the spectrum contains a strong high-energy X-ray component (Mushotzky et al., 1977). Long known as an irregular variable, X Per has been classified as a Be star with an 09.5 (III-IV)e spectral type and showing broad hydrogen emission and absorption features (Brucato and Kristian 1972, Hutchings et al., 1975). A 581-day period is indicated by the radial velocity study of Hutchings et al., (1975). This has been variously interpreted as an orbital period (about a black hole) or an apsidal period, the models having in common accretion on to a neutron star as the source of the pulsed X-rays. In 1977 an increase in brightness of the star was observed by Kalv (1977) and Guinan et al., (1978), and by April 1979 we had accumulated sufficient evidence to suggest that X Per undergoes periodic (≃ 6-year) outbursts (Dorren et al., 1979a).
The Symbiotic Binary System AG Pegasi
Authors: Keyes Charles D. , Plavec Mirek J. 
Published: July 2016

A complete coverage of the spectrum of AG Peg has been obtained between wavelengths 1200 − 7000 A by us, and can be supplemented by IR photometric observations by others. Our IUE observations yield a lower value of E(B-V), about 0.12. The two stellar components are easily recognized, but their characteristics are still rather uncertain.The cool component may be a normal M1.7 III giant, but the temperature and luminosity of the hot star remain largely indeterminate. Firstly, there are no good models for a hot subdwarf, and secondly, it is difficult to determine the relative contribution of the star itself and the surrounding hydrogen cloud.The emission lines observed in the UV have double or triple structure, indicating two or three distinct emitting regions.
Recent Observations of Energetic Electrons in Solar Flares
Authors: Kane S. R. 
Published: July 2016

SummaryIt has been apparent for the last few years that a large fraction of the total energy released during a solar flare appears initially in the form of energetic electrons accelerated during the impulsive phase. An estimate of the energy of these electrons is based on the observed hard x-ray spectra as well as the assumed form (thermal or non-thermal) of the electron distribution. Even after the basic form of the electron distribution is assumed, additional assumptions, such as the low energy cut-off in the case of the power law energy spectrum or existence of a multi-thermal source in the case of the thermal spectrum, are usually required. In order to test these assumptions, measurements of the hard x-ray spectrum with spatial resolution and covering a wide range of x-ray energy are essential. In absence of good spatial resolution, as is the case with most of the presently available hard x-ray observations, the impulsive x-ray emission at energies hv ≲ 10 keV is often unobservable because of the presence of a large background of relatively intense gradual emission associated with most flares. Observations made in the past suffered either because of the lack of a clearly identifiable impulsive x-ray emission at low energies (Peterson et al, 1973) or an adequate spectral resolution (Kahler, 1973). Thus so far it has not been possible to measure unambiguously the spectrum of impulsive x-rays ≲ 10 keV and hence to deduce a possible low energy cut-off in the energetic electron spectrum. Here we report briefly such an observation made with the ISEE-3 x-ray spectrometer experiment and its implications with regard to the characteristics of energetic electrons in solar flares.
Que pourra-t-on deduire des mesures de distance terre-lune par laser?
Authors: Kovalevsky J. 
Published: July 2016

Although several lunar laser ranging stations exist, only one is now fully operational: the McDonald station with internal observational errors of less than 15 cm. The interpretation of the data involves a great number of parameters relative to the Earth and the Moon which are listed.The lunar laser is particularly fit for those parameters that pertain to the Moon, and with future lasers accurate to 2 or 3 cm, it may be expected that this accuracy will be projected into these parameters. The probable determination of the semi-major axis to 1 cm accuracy for a few months mean would imply a new means of determining the non conservative part of the motion of the Moon. A similar precision is to be expected for the rotation of the Moon. The situation for the Earth parameters (Earth rotation and polar motion) is not so good, because of a rather weak geometry of the problem and the monthly one week gap in the observations. Nevertheless, it will give a very useful external check on other competing methods (radio-interferometry, laser or radio-satellites).
On Inconsistencies Found in Long-Term Parallax Series
Authors: Heintz W. D. 
Published: July 2016

Two recent papers (Hershey; Gatewood and Eichhorn; Astron. J., 1973) pointed out that:(1) A proper motion irregularity interpreted as orbital motion was found duplicated in another field.(2) The discontinuity found at one telescope failed to be confirmed by others, and might be ascribed to mere instrumental errors.After the duplication was discovered two years ago, further measurements have revealed an identical pattern in at least seven parallax stars. Yet the cause of the effect, and the reason for its absence in other cases, have not been located. Colour effects and filter problems appear to be ruled out. Indications for discontinuities occurring at other epochs were found. Thus, the question cannot yet be safely answered whether the small variations (one or two micron) of proper motions reported in some cases are spurious; in any case, great caution should be exercised in interpreting one-micron effects unless confirmation from another instrument is obtained.
Can the Solar System be Quantized?
Authors: Barnothy J. M. 
Published: July 2016

It is suggested that the general form of the constant of quantization, K in Schrödinger's equation, is not h/2π, but K=2sα-k, with s being the spin of the orbiting object, α the fine structure constant (1/137.0361), and k a small positive integer, or zero. For atoms k = 0; for planets and satellites k = 2, 3 or 4; for the solar system as a whole, revolving around the center of the Galaxy, k = 6. The probability that 16 objects of the solar system would follow this quantum rule by chance alone is 1 in 1016, suggestive that quantum mechanics, as we know it today, can be seen as a special case of a more general quantum mechanics of the future; it also supports the view expressed by Dirac, that h is probably not a fundamental constant.Section 1 contains the basic idea which induced me to undertake an investigation of a relationship between rotational and orbital angular momenta of planets; Sections 2–7 contain the experimental data, the application of the new quantum rule and the statistical evaluation whether the relationship proposed in Section 1, could have occurred by chance alone. The results obtained in Sections 2–7 are noteworthy in themselves, independently whether the basic idea is accepted or not.
Classification of New Spectral Lines of Fe XVII Observed in Solar Active Regions
Authors: Hutcheon R. J. 
Published: July 2016

SummaryThis summary reports new emission lines of Fe XVII observed in two coronal active regions (McMath regions 12624, 12628). The lines were recorded by a Bragg plane crystal spectrometer collimated to 3′ FWHM, with a gypsum crystal scanning the wavelength range 8–14 Å. This spectrometer, part of a three spectrometer package previously used by Parkinson (1972, 1973), was mounted aboard a Skylark rocket (SL 1206) launched from Woomera at 0535 UT on 26th November 1973. One of the active regions studied (12624) was observed about 60 minutes after the peak of an importance – N class CO flare.
Measurements of A Gamma-Ray Burst above 1 MeV
Authors: Koga R. , Simnett G. M. , White R. S. 
Published: July 2016

SummaryObservations of a burst of gamma radiation, starting at 201247 UT, 1972, May 14 are reported. The measurements were made with a 0.5 m2 actively shielded scintillator which was the front element of a double Compton telescope, during a balloon flight at an altitude of 5 mb from Palestine, Texas. The maximum intensity of the burst was 0.10±0.02 cm-2 s-1 above 1 MeV, and the duration was 3.5±0.4 min. The burst intensity during the first 2 min is constant to within 10%. No known electronic or detector malfunction could have produced this effect, and we believe it is a real event.
Detection of Submillimeter Lines of CO (0.65 mm) and H2O (0.79 mm)
Authors: Phillips T. G. , Kwan John , Huggins P. J. 
Published: July 2016

AbstractThe 91.5 cm telescope of NASA's Kuiper Airborne Observatory has been used, in conjunction with an InSb heterodyne receiver, to detect the J = 4-3 submillimeter transition of CO (461 GHz) and the 414−321 transition of H2O (380 GHz). The water emission was detected from the Orion “plateau” region.
Correlations between the λ2200 Feature, the Diffuse λ4430 Band and EB-V
Authors: Danks A. C. 
Published: July 2016

The λ2200 extinction feature has been measured from ANS observations of 30 stars. For each star, the depth of the λ2200 feature is compared to EB-V and the equivalent width of the diffuse band λ4430.A good correlation appears out to EB-V = 1.13. The various mechanisms for producing the diffuse and λ2200 features are discussed, and a discriminatory test is put forward based on observations of the Magellanic Clouds.
A New Approach to the Analytic Evaluation of Thermonuclear Reaction Rates
Authors: Haubold H. J. , John R. W. 
Published: July 2016

In our paper (Haubold and John 1978) we succeeded in a closed-form evaluation of the reaction rate by means of a special function, known as Meijer's G-function
This representation of the rate is appropriate to perform analytical operations (e.g. for the computation of energy generation in a fusion plasma).
High Energy Gamma Rays from Accretion Disc
Authors: Giovannelli F. , Karakula S. , Tkaczyk W. 
Published: July 2016

In the case of spherical symmetric accretion into a black hole, the matter may be heated up to the temperature KT = 0.1 mpc2 (Kolykhalov and Sunyaev, 1979). In such a hot plasma inelastic collisions of protons may produce Π° which is the gamma quantum source.In this work we determined γ-rays production spectrum in the comoving plasma reference frame, expected γ-rays spectrum for the case of spherica symmetric accretion of matter into a black hole and the upper limit to the number of black holes in Galaxy is evaluated.
On 3-He Rich Solar Particle Events
Authors: Möbius E. , Hovestadt D. 
Published: July 2016

Extensive measurements of the composition of energetic solar flare particles have revealed the frequent occurrence of solar flares with large enrichments of 3He and heavy ions compared to the composition of the solar atmosphere. The basic characteristics of these events can be summarized as follows:
–3He/4He-ratios up to more than 1 are observed–the 3He/4He-ratio increases with energy–no comparable enhancement of 2H or 3H is found–there is a strong correlation of 3He and heavy ion enrichment.
The Radio Lobes of Virgo A
Authors: Rottmann H. , Mack K.-H. , Klein U. , Wielebinski R. , Kassim N. , Perley R. 
Published: July 2016

In the framework of our multi-frequency study of Virgo A we have performed observations of Vir A at 10.55 GHz with the Effelsberg 100-m telescope. Using our improved CLEAN procedure for single dish data we have increased the dynamic range to some 40 dB.By applying our newly developed polarization CLEANing technique we are able to diminish instrumental polarization effects. Since Faraday rotation is negligible at λ2.8 cm the measured linear polarization is a direct trace of the projected magnetic field in Vir A. In combination with low-frequency data obtained with the VLA it is possible to determine parameters like spectral indices, break frequencies, and spectral ages.
New Results from Complete Samples of Faint Radio Galaxies and Quasars
Authors: Blundell K.M. , Rawlings S. , Eales S.A. , Lacy M. 
Published: July 2016

In any flux-limited sample a tight correlation of luminosity (P) and redshift (z) is inevitable. It is therefore necessary to obtain complete samples at lower and lower flux-limits in order to have adequate coverage of the P–z plane, essential if we are to decouple the trends in epoch from trends in luminosity. This we have done for a number of flux-limits — giving coverage of the P–z plane seen in Fig. 1. Our redshift information is spectroscopic; the results of Eales et al (in prep.), namely the increased scatter in theK-z plot for samples lower in luminosity than 3C, strongly warn us against using redshifts estimated from K-magnitudes.
Eclipse mapping and related techniques
Authors: Rutten René G. M. 
Published: July 2016

Eclipse mapping is a technique to deduce spatial structure on very small angular scales in eclipsing cataclysmic variable stars (CVs). By analysing the eclipse light curve, information is obtained on the brightness structure of the accretion disk and of the compact mass-accreting object in these systems. This information would otherwise be well beyond the resolving power of any optical telescope. Since the development of the eclipse mapping technique by K. Horne, about one decade ago, it has now become an important tool in the study of CVs. Originally eclipse mapping was employed to construct brightness maps of accretion disks in broad spectral bands. Recently, maps of much higher spectral resolution have become available from which optical and UV spectra have been reconstructed in spatial detail across accretion disks. Such information is very important for our understanding of the physics of the accretion process.In this paper I will describe the eclipse mapping technique and review recent results. In conjunction, I will briefly highlight other techniques related to the mapping of surface structure in CVs.
Observing stellar surface structure with the ESO-VLT interferometer
Authors: Von Der Lühe O. , Solanki S. , Reinheimer Th. 
Published: July 2016

The ESO Very Large Telescope (VLT) has the capability to coherently combine the light from four 8m telescopes and from smaller Auxiliary telescopes with baselines 4m and 200m (VLT Interferometer or VLTI). The resulting resolution approaches 0.5 milli-arcsec at visible wavelengths and 1 milli-arcsec in the near infra-red. We estimate that about 2000 nearby bright stars can be resolved with these baselines. The surface of about 400 stars, mainly K and M giants, can be mapped with a resolution of a dozen pixels or better across the stellar surface. This resolution permits detailed studies of the structure of stellar atmospheres, their hydrodynamics and magneto-hydrodynamics. VLTI can easily resolve starspots and very likely also convection cells on an active K-type giant at 10pc distance. A marginal detection of the largest starspots on a very active solar-type star at the same distance may be possible, but it appears very unlikely that the surface structure on an inactive solar-type star can be imaged.We present computer simulations of stellar surfaces to study in detail the response of the interferometer to an extended, complex source. First results which simulate the end-to-end process in a simplified manner indicate that useful maps can be produced provided that a sufficient number of baselines are combined in Earth-rotation synthesis mode. We also give arguments that high spectral resolution will prove essential to constrain reconstructed maps.