Bright Spectra Research Articles

The Wavenumber-Frequency Spectra of Satellite-Measured Brightness in the Tropics

Abstract The wavenumber-frequency spectra of satellite-observed brightness have been examined for the period 1 February 1967 through 29 February 1968 for the latitude belt 20N to 20S. It was found that the quasi-stationary modes and low wavenumbers contain most of the power. The propagating wave activity was located primarily in the 5–15N latitude zone. Perturbations with periods of 12.5 days and wavenumber 5 and about 6 days and wavenumber 9 were prominent. These are consistent with Rossby waves and easterly waves. Since the propagating brightness spectra are due to propagating clouds, the results indicate a traveling heat source as being important in the generation and maintenance of those waves. There was no indication in the brightness spectra of periods and wavelengths consistent with Kelvin waves. However, a tropospheric heat source is not ruled out for those waves.

An upper limit on H2ultraviolet emissions from the Martian exosphere

A large number of Mariner 9 bright limb ultraviolet spectra have been averaged to obtain an upper limit to the ultraviolet H2 emissions from the Martian exosphere. The strongest signal would have been the υ′ = 6 → υ″ = 13 Lyman band, which had an upper limit of 1.5 R.

VY SCL, A NEW RAPID BLUE VARIABLE.

ABSTRACT Rapid variations with an underlying 500-second periodicity are reported for VY Scl, a blue star at the south galactic pole. Broad absorption lines are visible beneath the bright line spectrum. It is suggested that the star is a dwarf nova, not the R CrB-type star previously proposed. Key words: variable star - photometry - spectrum

Stridulatory organs in spiny orb‐weaver spiders

A stridulatory organ is here described for the first time in the family Argiopidae. The file is on the surface of the lungbook covers, and the scraper is on the base of the femora. Altogether seven different kinds of stridulatory organs have been distinguished in spiders according to the positions of the files and scrapers. The organ now described in the spiny orb‐weavers of the genus Micrathena was previously known only in a few genera of the family Erigonidae. In one of the species of Micrathena the ridges of the stridulatory file are sufficiently close together to give bright diffraction spectra at incidences near grazing. The primitive polygonal pattern on the surface of the cuticle of spiders is illustrated, and the mode of formation of the stridulatory file is suggested.

Interpretation of radar and radio observations of Venus

Constraints on the atmospheric conditions at the surface of Venus are determined from the radar angular scattering law, radar cross section, and microwave brightness spectrum. These constraints are satisfied by the conditions [T(surface) = 750 ± 50°K, P(surface) = 110 ± 30 atm] inferred from extrapolation of the Mariner 5 pressure and temperature profiles to the surface given by the radar radius. Refraction by such a dense atmosphere will complicate radar mapping of the surface (especially near the limbs of the planet where the distortion of the apparent surface is not negligible). A rigorous derivation, considering refraction effects, is given for the relationship between delay-Doppler coordinates and spherical coordinates on the planet's surface.

Venus: An Isothermal Lower Atmosphere?

Use of Earth-based microwave data in extrapolating the atmospheric profile of Venus below the region probed by Mariner V and Venera 4 reveals an isothermal layer at 670 degrees +/- 20 degrees K that extends to an altitude of 7 +/- 2 kilometers. This model gives a value of 6054.8 kilometers for the radius of Venus, and agreement with brightness spectrum, radar cross sections, and results of microwave interferometry.

The Binary-Star Hypothesis for the Nucleus of NGC 1514

It is well known that the central star of the planetary nebula NGC 1514 (α50 = 4h06m.1, δ50 = +30°39'; lII= 165·5, bII = −15·3) differs from the other planetary nuclei by its high brightness (relative to the nebula) and late-type spectrum. The difference B∗ – Bn = 1m.9, and especially the A0-spectral type (Chopinet, 1963) are quite atypical for central stars. For these reasons we began a complex study of this object (Kohoutek, 1967; Kohoutek and Hekela, 1967) on the basis of the following sources of observational material: (1)Palomar Sky-Survey prints (Schmidt-camera, Palomar Observatory);(2)direct photographs in UBV system with the 2-m Schmidt-camera in Tautenburg (1962);(3)photoelectric UBV photometry with the 65-cm reflector at Ondřejov (1964–65),(4)(4) spectrograms of the central star using the 122-cm reflector in Asiago (1965), and relatively infrequent observational data from the older literature.

The Galactic Spur

New observations have been made of the radio emission from the galactic spur at lII = 30° at 237 Mc/s to investigate the detailed structure of the sharp edges and the distribution of emission over the declination range observable from Jodrell Bank. The weak radio emission at 1415 Mc/s was measured at three sections of the northern edge of the spur, and the results were also compared with the 38 Mc/s survey of the region obtained by Costain and Smith (1960). This data allows a rediscussion of the nature of the spur. The spur has a characteristic sharp outer edge which in places falls to half intensity in 0°.5. Also it has structure parallel to the edge which indicates that the source is a multiple shell like the Cygnus Loop which it resembles in brightness temperature, spectrum and structure. If its radius is taken as 20 pc its centre lies at a distance of 30 pc and is composed of shells each with a thickness of about 2 pc. The observed emission from both the Cygnus Loop and the galactic spur is rather more than expected from background cosmic ray electrons alone, emitting in the enhanced magnetic field of the expanding envelope, and suggests that some of the emission comes from cosmic rays generated within the shell sources. The polarization of the main ridge of the spur confirms that it is close to the Sun and also that it radiates by the synchrotron process. It is concluded that the galactic spur, like the Cygnus Loop, is a supernova remnant.

Luminescence studies of rare earth complexes: Benzoylacetonate and dibenzoylmethide chelates

Systematic studies of the luminescence of the trisbenzoylacetonates and trisdibenzoylmethides of the trivalent rare earth ions (except promethium and cerium) are reported. Molecular fluorescence and phosphorescence spectra of both series of chelates are presented. The chelates have been arranged according to total luminescence and phosphorescence yields, and the variations in yields are interpreted in terms of internal radiationless processes. The role of intramolecular energy transfer in these systems as a quenching mechanism is discussed. Photographs of bright line spectra of coordinated Eu 3+, Tb 3+, Dy 3+, and Sm 3+ are included and the possibility of employing these compounds as optical masers is pointed out.

The Emission Line Spectrum of the Eclipsing Variable AR Pavonis

The bright line spectrum of AR Pav is described. During eclipse the intensity of the H lines weakens relative to the nebular lines; He I weakens more, while He II 4686 nearly disappears. Stratification as in a planetary nebula is suggested. In the P Cyg structure of the Balmer lines the red component is always stronger than the violet, but equality is approached for over 100 days following eclipse. The separation of the components narrows during eclipse by an amount which varies in different cycles. Outside eclipse the mean separation obeys Struve's relation |$V^3\propto P^{-1}$| for gaseous rings. A model of a thick ring subject to differential rotation is considered and profiles computed geometrically for various types of eclipse. The observed narrowing of components is not reproduced in this model. As an alternative an expanding ring is considered briefly, and this model predicts symmetrical narrowing during eclipse.

Discussion

In the period following the papers on instability among the hot stars of low luminosity, Dr L. Gratton presented a brief account of work in progress on η Carinae by Dr Platseck, Miss Ringuelet, and himself at Córdoba and La Plata. The bright line spectrum of η Carinae is being studied in detail; one interesting observation is that the emission lines of Ti 11 are quite weak as compared to their intensities in novae of comparable excitation. The Balmer lines are also faint. The hydrogen emission lines consist of fairly wide structures upon which are superimposed narrow emission cores, as well as absorption features. The La Plata workers find that the narrow emission lines originate in the nuclear star, while the bright lines that arise from the nebulosity in the immediate vicinity are very wide, their breadths corresponding to a velocity range of 500 to 1000 km./sec. The radial velocities vary greatly from one part of the nebula to another. Gratton and his colleagues believe that η Carinae is actually a member of the Carina O-association upon which it is seen superimposed. The corrected distance modulus of this complex is 12.3 magnitudes, with an uncertainty of less than half a magnitude. It follows that η Carinae at its maximum in 1843 had an absolute magnitude almost certainly exceeding −13, and even now is a fairly luminous object of M = −5 or −6. The La Plata astronomers believe it to be improbable, therefore, that η Carinae is a nova-like variable or a super-nova, but think rather that the object is to be regarded as similar to S Doradus or Hubble's variables in extragalactic nebulae. They comment on the probable membership of both S Doradus and η Carinae in O-associations, and suspect that this connexion may be of great evolutionary significance.

Physiological sensation curves of an equal brightness spectrum.

The physiological sensation curves for an equal brightness spectrum and an equal energy spectrum were studied by means of the electro-stimulation method at the retinal fovea. 1. The equal brightness spectrum was obtained by adjusting the intensities of spectral lights so as to give the equal CFF value (10 cps.). 2. The physiological sensation curves for the equal brightness spectrum and the equal energy spectrum were compared with each other. The main difference consists in that the “blue” sensation curve is greatest for the equal brightness spectrum, while the “green” sensation curve was greatest for the equal energy spectrum. 3. It was found that two kinds of thresholds were obtained for one wavelength in a certain range of wavelengths, and the question arose which of them should be used for the sensation curves. The mechanism of the double thresholds was studied by the seeing frequency method, and the experimental basis for the construction of the sensation curves was provided.

Some Quantitative Aspects of an Opponent-Colors Theory I Chromatic Responses and Spectral Saturation

Saturation discrimination is assumed to be dependent on the ratio of chromatic to achromatic components in the sensory response to a given wavelength. The usual methods of measurement do not, however, permit independent control of the chromatic and achromatic variables. On the basis of an opponent-colors theory of vision, a method is described for measuring directly and separately the spectral distributions of the chromatic components. A series of experiments is reported in which this method was used to obtain measures of the paired chromatic responses associated with the four primary spectral hues. Results are reported for two observers, 1° foveal test field, for an equal brightness spectrum (10 mL), and a neutral state of adaptation (10 mL). The measured chromatic responses, together with achromatic (luminosity) functions measured earlier for the same observers, are used to predict the form of the spectral saturation discrimination function.

On emission lines at high kinetic temperature.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On emission lines at high kinetic temperature. Thomas, R. N. Abstract If one admits the existence of a general outer stellar atmosphere whose kinetic temperature exceeds the radiation temperature of the star, some other mode of energy transfer than radiation is implied. There exists thus the possibility of increasing the emission in certain spectral regions without requiring a diminution in others. The conditions for a net chromospheric emission under conditions of high kinetic temperature and non-thermodynamic equilibrium are presented, with results in general considerably different from the earlier conclusions of Menzel. The most pressing refinement needed for the general case over the type calculations already made for the solar chromosphere, where Lyman emission and Balmer absorption were found, lies in the consideration of collisional excitation from the n = 2 level. The inclusion of such a term may force the earlier Balmer members into emission under conditions of sufficiently large electron density and kinetic temperature. It is suggested that the phenomenon may find application in the transitory bright line spectrum observed by Struve in RR Lyrae. Institute of Advanced Study, Princeton University, Princeton, N. J. Publication: The Astronomical Journal Pub Date: April 1949 DOI: 10.1086/106229 Bibcode: 1949AJ.....54..137T full text sources ADS |

A New Method for Oblique Microscopical Illumination

The purpose of the method is to facilitate the resolution of extremely fine regularly-repeated markings on microscopical objects. Resolution is obtained by using the objective as an eyepiece to observe the direction and degree of obliquity of the light; these are controlled by movements of the mirror. To enable the objective to be used in this way, the condenser is raised above the position required for so-called ‘critical’ illumination. The diffraction-spectrum formed by the markings on the object is clearly seen while the mirror movements are being made, and it is easy to produce a bright and complete spectrum.

The Determination of the Sign and the Energy Spectrum of Primary Cosmic Radiation

An experiment is reported in this paper for the measurement of the complete azimuthal effect. This experiment was performed in Mexico City (geomagnetic latitude 29\ifmmode^\circ\else\textdegree\fi{}, altitude 2242 m above sea level) for constant zenith angles 20\ifmmode^\circ\else\textdegree\fi{}, 40\ifmmode^\circ\else\textdegree\fi{}, and 60\ifmmode^\circ\else\textdegree\fi{}. A characteristic feature is that the length of the atmospheric path is constant, hence the assumption is made that the number of secondaries detected by the cosmic-ray telescope is a measure of the number of primaries. The analysis yields an energy spectrum of the primary radiation of the form $\frac{K}{{E}^{1.45}}$ ($E$=energy, $K$=constant). There is no evidence of negative primary particles. The results are subject to revision because the penumbra bands at this latitude are only imperfectly known, and also because of the resolving power of our present apparatus. The possibility of a bright line spectrum, or of such a spectrum superimposed on a continuous distribution, is not ruled out. The possibility of negative primaries is excluded within the limits of experimental error. The spectrum obtained from our experimental data agrees completely with that determined from the experiment of Gill, carried out at Lahore, Punjab, India. The result is valid in the energy range from about 350 to 600 millist\"ormers, or 6 to 21 Bev if the primaries are protons.

Forbidden Lines of Fe VII in the Spectrum of Nova RR Pictoris (1925)

THE bright line spectrum of Nova RR Pictoris (1925) is characterized in the later stages by a group of lines in the visible region, of which the most prominent, 5723 and 6087, form with H+ and 4686 of He II the dominating lines of the spectrum1. These lines have not been found in any other spectrum and no adequate explanation of them has been given so far.

On Anchoring the Mercury Pool Cathode Spot

Certain metals projecting through a mercury surface are known to have the property of ``anchoring'' the cathode spot. A variety of metals have been examined for this ability and it has been found to exist for all of them tried, Fe, Pd, Zr, Pt, Cr, Cb, Ir, Mo, Ta, W. The property depends upon wetting of the metal by the mercury, and this in turn depends upon having a clean metallic surface. The spot lengthens into a fine bright cathode line (C.L.) at the meniscus edge. These metals differ in the ease of cleaning and of maintaining cleanliness. Electrolysis, hydrogen firing, vacuum firing and ion bombardment were used in different cases. The first five show attack by the cathode spot, the Mo shows slight disintegration. Besides the bright line spectrum, the C.L. has also a strong, continuous spectrum from red into ultraviolet which is quite different from hot body radiation. The C.L. consists of a multitude of small emitting areas which are in constant rapid and chaotic motion. The details as shown by moving film photographs differed with the anchor. Cb showed the most clear-cut phenomena. Its individual spots passed 0.22 amp. each and they moved with a predominant velocity of 46 cm/sec. They oscillated in intensity with a period of the order of 10−4 sec. Their current density was ∼9000 amp./cm2. The behavior of the C.L. under different kinds of varying current has been observed, and the change in C.L. length with current plotted. Increasing the arc current while maintaining the length of C.L. fixed resulted in a lowering of the C.L. even to below the pool level and to the formation of a trough in the liquid outside the C.L. This helps explain the mechanism of spot freeing at large current densities and gave the upper limit for a circular anchored spot at about 40 amp./cm.

Trichromic Vision

THE trichromics, that is those who see three colours in a bright spectrum, red, green and violet, are confused by many with the anomalous trichromatics, whereas they are quite distinct. The anomalous trichromatics, as defined by the late Lord Rayleigh, make an anomalous equation and do not agree with the normal equation, and they may not be colourblind. The trichromics are invariably dangerously colour-blind, and though they may make an anomalous equation they may also agree with the normal equation.

On the Axial Rotation and Spectra of Stars

Struve's remarkable relation between high observed axial rotations of stars and their bright line spectra is considered theoretically. It is shown that the two phenomena are closely related to the same electromagnetic effects that account for the anomalous solar rotation. High electromagnetic winds, resulting from crossed electric and magnetic fields, account for the high apparent rotational velocity and transfer sufficient momentum to the star in the course of stellar time to account for the high true rotations necessary to produce fission. The large electromagnetic wind velocities require the presence of comparatively large radial electric fields and it is shown that these can add sufficient additional excitation energy to the atmospheric ions to produce bright line spectra. Thus, high apparent axial rotations, high true rotations and bright line spectra in stars are intimately related and the existence of one, usually demands the presence of the others. An approximate expression is derived for the time rate of increase of angular momentum in a star.