scholarly journals ABSORPTION OF SUNLIGHT BY ATMOSPHERIC SODIUM

1957 ◽  
Vol 35 (8) ◽  
pp. 918-927 ◽  
Author(s):  
J. A. Scrimger ◽  
D. M. Hunten
Keyword(s):  
Spectral Region ◽  
Scattered Light ◽  
Stray Light ◽  
Low Density ◽  
The Sun ◽  
Sodium Vapor ◽  
Sodium Layer ◽  
Residual Intensity ◽  
Narrow Spectral Region ◽  
The Continuum

A photometer has been built which is sensitive to light only in a very narrow spectral region near the sodium D-lines. The light is scattered by sodium vapor at low density and the scattered light recorded by a photoelectric spectrometer. The latter resolves the two lines and allows the effect of stray light to be eliminated. With sunlight as the source, the radiation detected is at the bottom of the Fraunhofer lines and the residual intensity there may be measured. It is found that this intensity decreases slightly (relative to the continuum) as the sun approaches the horizon. This effect is attributed to atmospheric sodium; the amount found by this method agrees well with that deduced from twilight measurements. The thickness of the sodium layer in atoms/cm.2 varies between 3 and 9 × 109 in winter and is about 1 × 109 in April. The measurements also give the residual intensities of the Fraunhofer lines in the incident sunlight, averaged over the whole of the sun's disk. These are (5.90 ± 0.46)% for D1 and (5.06 ± 0.24)% for D2.

scholarly journals Lithium Observations in the Sun

1968 ◽  
Vol 1 ◽  
pp. 243-246
Author(s):  
Edith A. Müller
Keyword(s):  
Unknown Origin ◽  
Absorption Feature ◽  
The Sun ◽  
Degree Of Ionization ◽  
Lithium Abundance ◽  
Resonance Doublet ◽  
Lower Temperature ◽  
Central Depth ◽  
The Continuum

The determination of the lithium abundance in the solar atmosphere is essentially based on the LiI resonance doublet at λ 6707·761 and 6707·912 Å. These two lines form a very faint absorption feature, the central depth of the stronger component being of the order of 1% of the continuum. The violet component, which is also the stronger of the two, occurs near the red wing of a faint solar line of unknown origin, and the lines appear to be blended with other faint lines including possibly the doublet of the Li6 isotope (the isotopic shift being 0·160 Å). No other line of LiI has been detected in the Fraunhofer spectum of the undisturbed solar disk. This is nothing surprising, because practically all lithium is expected to be ionized in the photosphere on account of its low ionization potential (Xion = 5·37 e.v.). In sunspot spectra the lower temperature reduces the degree of ionization of lithium and causes a strengthening of the LiI lines. In fact, the LiI resonance lines which appear as a very faint absorption feature on disk spectra are about 50 times stronger in spot spectra. Furthermore, the very weak feature at λ 6103·6 Å was identified by Dubov (1964) and by Schmahl and Schröter (1965) as due to the 2s 2S–3d 2D transition of LiI. Both the resonance doublet and the faint feature at 6103·6 Å have been used by the above-mentioned authors to derive the lithium abundance in spots.

scholarly journals Investigation of the influence of plasma source power on the properties of magnetron sputtered Ta2O5 thin films

2021 ◽  
Vol 255 ◽  
pp. 03005
Author(s):  
Manuel Bärtschi ◽  
Daniel Schachtler ◽  
Silvia Schwyn-Thöny ◽  
Thomas Südmeyer ◽  
Roelene Botha
Keyword(s):  
Thin Films ◽  
Scattered Light ◽  
Plasma Source ◽  
Stray Light ◽  
Optical Losses ◽  
Coating Materials ◽  
Source Power ◽  
Light Losses ◽  
Interference Coating ◽  
Deposition Processes

To enable the production of sophisticated optical interference coating designs, coatings with very low absorption and stray light losses and excellent layer thickness deposition accuracy are required. The selection and optimization of suitable coating materials and deposition processes are consequently essential. This study investigated the influence of the plasma source power on the optical properties, layer uniformity and stress, scattered light behavior and optical losses of magnetron sputtered Ta2O5 thin films.

scholarly journals Interferometric Observation of the F-Corona Radial Velocities Field Between 3 and 7 R⊚

1985 ◽  
Vol 85 ◽  
pp. 77-80
Author(s):  
P.V. Shcheglov ◽  
L.I. Shestakova ◽  
A.K. Ajmanov
Keyword(s):  
Scattered Light ◽  
Interplanetary Dust ◽  
Radial Velocities ◽  
The Sun ◽  
Continuous Component ◽  
The North ◽  
The Earth ◽  
Fabry Perot ◽  
Interferometric Observation ◽  
Sky Brightness

AbstractDuring the July 31, 1981 solar eclipse, F-corona interferograms near MgI λ 5184 Å were obtained using a Fabry-Perot etalon (FPE) with an FWHM of 0.5 Å (corresponding to 30 km/sec) and an image tube. Radial velocities Vr of the interplanetary dust (i.d.) were measured in different directions.Both prograde and retrograde motions of i.d. in the ecliptic region is discovered. Most of velocity values do not exceed 50 km/sec. A negative velocity component appears after averaging all Vr for all directions. Its average increases to − 20 km/sec toward the Sun. Some ejections are observed. The strongest (+ 130 km/sec) is located at the north ecliptic pole at a distance of 6 to 7 R⊙.From the lack of unshifted Fraunhofer lines in the scattered sky light, we conclude that the sky brightness continuous component is predominant and its source is K-corona scattered light in the Earth’ s atmosphere.

scholarly journals Heating of the Interstellar Medium by Supernova Remnants

1983 ◽  
Vol 101 ◽  
pp. 385-392
Author(s):  
Donald P. Cox
Keyword(s):  
Interstellar Medium ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Low Density ◽  
The Sun ◽  
X Ray ◽  
Interstellar Material ◽  
X Ray Background

We observe the heating of interstellar material in young supernova remnants (SNR). In addition, when analyzing the soft X-ray background we find evidence for large isolated regions of apparently hot, low density material. These, we infer, may have been heated by supernovae. One such region seems to surround the Sun. This has been modeled as a supernova remnant viewed from within. The most reasonable parameters are ambient density no ~ 0.004 cm−3, radius of about 100 pc, age just over 105 years (Cox and Anderson 1982).

scholarly journals 2. A Comparison of the Composition of New and Evolved Comets

1977 ◽  
Vol 39 ◽  
pp. 15-23 ◽  
Author(s):  
B. Donn
Keyword(s):  
Intensity Ratio ◽  
Age Groups ◽  
Apparent Difference ◽  
The Sun ◽  
Age Group ◽  
Significant Difference ◽  
Second Category ◽  
Emission Intensity Ratio ◽  
Perihelion Passage ◽  
The Continuum

The intensity ratio of the continuum to the molecular emissions was estimated in the spectra of eight-five comets. These consisted of 34 new, 1/a (orig) < 100 x 10-6 AU-1, 31 more evolved with 102 < 1/a < 104, and 20 periodic comets, P < 103 years. In each age group the comets were divided into two distance intervals, the first observed at less than 1 AU from the sun and the second category observed at more than 1 AU. No significant difference among the patterns of relative intensity distribution among four age groups was found. No general evidence for a difference between pre- and post-perihelion observations was found although in a few cases a pronounced effect occurs. Four conclusions are drawn. (1) There is no readily apparent difference in continuum to emission intensity ratio between new and more evolved comets. (2) An intrinsic distribution of this characteristic does occur. (3) Periodic comets with weak continua derived from new comets with the same property. (4) No weakening of the continuum in general occurs following perihelion passage. The infrared evidence for Comet Encke suggests that the faintness of its continuum may be caused by a size distribution containing only particles larger than about 10 μm.

Why can’t the sun bloom roses in Spanish?

2011 ◽  
Vol 11 (2) ◽  
pp. 241-258 ◽  
Author(s):  
Guillermo Rodríguez
Keyword(s):  
Locus Of Control ◽  
Necessary Conditions ◽  
Binary Classification ◽  
External Factors ◽  
The Sun ◽  
Change Of State ◽  
Syntactic Behavior ◽  
Work Done ◽  
The Continuum

Levin and Rappaport (1995) have proposed a binary classification for change of state verbs that revolves around the locus of cause for these changes: whether the cause is internal or external to the entity undergoing change. They claim this distinction is crosslinguistically viable and explains the syntactic behavior of these predicates. Based on work done by Smith (1970) and Wright (2001), this paper argues for an extension of Levin and Rappaport’s binary classification. Instead, I propose a continuum resulting from the analysis of corpora in English and Spanish for verbs that would enter the binary categories advanced by Levin and Rappaport. One of the problematic pairs of verbs for their classification when applied to Spanish, florecer ‘to bloom’ and marchitar(se) ‘to wilt’ is analyzed in detail. The continuum proposed here extends Levin and Rappaport’s categories and takes into account the locus of control of the change and whether external factors may be necessary conditions for the change to occur. In particular, this new focus can account for the presence or absence of the clitic se with some of the predicates in Spanish.

scholarly journals Physical Observations of the Short-Period Comet 1969 IV

1972 ◽  
Vol 45 ◽  
pp. 27-34
Author(s):  
K. I. Churyumov ◽  
S. I. Gerasimenko
Keyword(s):  
Spectral Region ◽  
Sunspot Area ◽  
Radius Vector ◽  
Short Period Comet ◽  
Short Period ◽  
Single Emission ◽  
The Continuum ◽  
Period Comet

The new short-period comet Churyumov-Gerasimenko, discovered by the authors on plates taken by the Kiev University cometary expedition to Alma-Ata in September 1969, was systematically photographed with fast telescopes at Byurakan and Alma-Ata until March 1970. Measurements were made of the photographic magnitude of the photometric nucleus, as well as of the photographic and photovisual integral magnitudes. The variations in nuclear magnitude were found to be well correlated with changes in the total sunspot area. The integral photometric parameters are Hy = 11.91±0m.54 and n=4.0±0.8 (in the photographic spectral region). Deviations of the tail axis from the prolonged radius vector were considerable. A spectrogram shows the continuum and emission of CN, C2 and C3 in the head, the continuum and a single emission (perhaps CO+) in the tail.

scholarly journals Dust Measurements in the Outer Solar System

1994 ◽  
Vol 160 ◽  
pp. 367-380
Author(s):  
Eberhard Grün
Keyword(s):  
Solar System ◽  
Interstellar Dust ◽  
Thermal Emission ◽  
Scattered Light ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Spatial Density ◽  
Outer Solar System ◽  
The Sun

In-situ measurements of micrometeoroids provide information on the spatial distribution of interplanetary dust and its dynamical properties. Pioneers 10 and 11, Galileo and Ulysses spaceprobes took measurements of interplanetary dust from 0.7 to 18 AU distance from the sun. Distinctly different populations of dust particles exist in the inner and outer solar system. In the inner solar system, out to about 3 AU, zodiacal dust particles are recognized by their scattered light, their thermal emission and by in-situ detection from spaceprobes. These particles orbit the sun on low inclination (i ≤ 30°) and moderate eccentricity (e ≤ 0.6) orbits. Their spatial density falls off with approximately the inverse of the solar distance. Dust particles on high inclination or even retrograde trajectories dominate the dust population outside about 3 AU. The dust detector on board the Ulysses spaceprobe identified interstellar dust sweeping through the outer solar system on hyperbolic trajectories. Within about 2 AU from Jupiter Ulysses discovered periodic streams of dust particles originating from within the jovian system.

scholarly journals Low Density Drivers of Strong Interplanetary Shocks

1996 ◽  
Vol 154 ◽  
pp. 5-13
Author(s):  
A. Hewish
Keyword(s):  
High Speed ◽  
Solar Maximum ◽  
Coronal Holes ◽  
Strong Shock ◽  
Low Density ◽  
The Sun ◽  
Interplanetary Shocks ◽  
Fast Solar Wind ◽  
Proton Temperature ◽  
High Speed Flows

AbstractThe theory that most, if not all, interplanetary shocks are caused by coronal mass ejections (CMEs) faces serious problems in accounting for the strongest shocks. The difficulties include (i) a remarkable absence of very strong shocks during solar maximum 1980 when CMEs were prolific, (ii) unrealistic initial speeds near the Sun for impulsive models, (iii) the absence of rarefaction zones behind the shocks and (iv) sustained high speed flows following shocks which are not easily explained as consequences of CME eruptions. Observations of the proton temperature near 1 AU indicate that strong shock drivers have properties similar to high speed streams emitted by coronal holes. Eruptions of fast solar wind from coronal holes influenced by solar activity can explain the occurrence of the strongest interplanetary shocks.

scholarly journals Observations of Solar Continuum Emission at Decameter Wavelengths

1990 ◽  
Vol 142 ◽  
pp. 513-514
Author(s):  
Ch. V. Sastry
Keyword(s):  
Electron Temperature ◽  
Brightness Temperature ◽  
Large Scale ◽  
Continuum Emission ◽  
The Sun ◽  
Temperature Variations ◽  
One Dimensional ◽  
Wave Radio ◽  
Grating Interferometer ◽  
The Continuum

We observed the continuum emission from the radio sun when there is no burst activity at λ = 8.7 m with the large decameter wave radio telescope at Gauribidanur (Latitude 13° 36‘ 12“ N and 77° 27‘ 07“ E) with a resolution of 26'/40'. A compound grating interferometer with one dimensional resolution of 3' is also used. These observations are made during August 1983 and June 1986. The brightness temperature at the center of the sun varied from 0.2 106 K to 0.8 106 K during these periods on time scales of several hours to a day. Since the sun is absolutely quiet during these periods we believe that the radiation is purely thermal in nature. In this case the observed brightness temperature variations imply large scale density variations by more than a factor of three if the corona is optically thin at these wavelengths. Alternatively if the corona is optically thick the observations imply real electron temperature variations with or without accompanying density variations.

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