Additional Members of the Balmer Series in the Absorption Spectrum of the Sun

1941 ◽  
Vol 53 ◽  
pp. 38
Author(s):  
Gerard F. W. Mulders
Keyword(s):  
Absorption Spectrum ◽  
The Sun ◽  
Balmer Series

scholarly journals Note on the intensity decrement in the balmer series

1919 ◽  
Vol 96 (675) ◽  
pp. 112-119 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Low Pressure ◽  
Quantitative Comparison ◽  
The Sun ◽  
Previous Knowledge ◽  
Balmer Series ◽  
Celestial Bodies ◽  
Theoretical Considerations

One of the most remarkable examples of spectrum lines which are common in celestial bodies, but which have hitherto resisted all attempts to reproduce them in the laboratory, is afforded by the higher members of the Balmer series of hydrogen. As many as 29 members of this series have been observed by Dyson and Evershed in the chromosphere of the sun, but the greatest number observed in the laboratory by Ames and by Cornu was only 13, and the last of these were of such a character that it would hardly have been possible to record them without a previous knowledge of their localisation. In many respects the failure to reproduce in the laboratory lines whose chemical origin is known, and which are so prominent in celestial spectra, is even more conspicuous than in the case of the nebular and coronal lines, which cannot yet be referred to any atom known in chemistry, and which may be due to substances which do not, or perhaps cannot, exist under terrestrial conditions. A further interest has been added to the problem by the important theoretical wrork of Bohr, whose theory of the production of the Balmer series requires that the space occupied by a hydrogen atom, in the process of emitting lines of the higher members of the Balmer series, is such that these radiations cannot be expected to be visible except under conditions of extremely low pressure. Bohr has pointed out that this view is consistent with the appearance of the lines in celestial spectra, and our inability to produce them under the conditions ordinarily obtaining in the laboratory. Liveing and Dewar have found that in a mixture of the more volatile gases of the atmosphere, consisting mainly of neon and helium and containing hydrogen, the Balmer series could be traced as far as the ninth member; and in a recent investigation we have made a quantitative comparison of the distribution of intensity in the earlier members of the series in hydrogen, and in neon containing hydrogen as an impurity. This observation of Liveing and Dewar is remarkable, but we have recently found that similar results can be obtained in helium containing hydrogen at pressures so great that, on the theoretical considerations above referred to, it would seem impossible that these radiations should be detected.

scholarly journals Subionization and decelerated-flow in the vicinity of a B-shell star

1981 ◽  
Vol 59 ◽  
pp. 539-541
Author(s):  
J. Zorec
Keyword(s):  
Absorption Spectrum ◽  
Main Sequence ◽  
Type B ◽  
Balmer Series ◽  
B Stars ◽  
Normal Absorption ◽  
Balmer Lines ◽  
Fixed Order ◽  
Shell Star ◽  
Normal Spectrum

Three types of spectra have been extensively observed among mainsequence B stars. B-normal is the classical absorption spectrum which defines a normal main-sequence B star. Be is a B-normal spectrum except : (i) some absorption lines, notably the first hydrogen Balmer series members, are replaced by emission lines; (ii) some lines from some singlyionized metals, not normally present in B stars, sometimes appear, either in emission or absorption. Be-shell is a Be spectrum with narrow and deep absorption cores in the Balmer and singly-ionized metal lines. A fourth type, B-shell, has been identified as a B-normal, absorption, spectrum except for the presence of FeII lines, and narrow, deep absorption cores in these and the hydrogen Balmer lines. Once thought to each represent a different kind of star, these spectra are now realized to simply represent different temporal phases, which one and the same star can traverse, apparently in no (as yet) fixed order. Some of the brightest stars --- eg γ Cas, 59 Cyg, Pleione --- have been observed in all of the 3 prominant phases; some stars, in only some of them; 70 % of the B stars have been observed only in the B-normal phase.

scholarly journals THE SENSIBILITY OF THE SUN-FISH, LEPOMIS, TO MONOCHROMATIC RADIATION OF LOW INTENSITIES

1932 ◽  
Vol 15 (3) ◽  
pp. 307-328 ◽  
Author(s):  
Harry Grundfest
Keyword(s):  
Absorption Spectrum ◽  
Orienting Response ◽  
Monochromatic Radiation ◽  
New Method ◽  
The Sun ◽  
Visibility Function ◽  
Visual Orienting ◽  
Photosensitive Substance

1. A test is proposed of the hypothesis that visual purple is the photosensitive substance concerned in dim vision. It is based on the fact that fish visual purple is different from that of other vertebrates. If the hypothesis is correct, the fish dim-visibility function should be different from that of other vertebrates and should be determined by the absorption spectrum of its visual purple. 2. A new method is described for obtaining the visibility function of fish, in quantitative terms. It depends on the measurement of the least amounts of various spectral energies which will produce a visual orienting response to the displacement of a constant background. 3. Data are presented on thirteen animals. It is shown that the maximum of the visibility function is identical with the maximum of the absorption spectrum of fish visual purple. The shapes of the visibility curves obtained are, however, variable and different from that of the absorption spectrum. 4. The possibility that Lepomis visual purple is different from that of other fish is ruled out by a series of measurements which confirm the results of Koettgen and Abelsdorff on other fish. 5. Reasons are given for the conclusion that there are present in Lepomis special conditions which distort the visibility curve out of true agreement with that predictable from the absorption spectrum of its visual purple. The suggestion is made that the presence of light absorbing, but not light sensitive, pigments is responsible for this distortion. One of these pigments may perhaps be carotin while the second is unspecified.

scholarly journals Absorption bands of HCN in the photographic infra-red

1934 ◽  
Vol 147 (862) ◽  
pp. 434-442 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Line Width ◽  
Vibrational Energy ◽  
Pressure Effect ◽  
The Sun ◽  
Absorption Bands ◽  
Infra Red ◽  
Tungsten Lamp

The infra-red absorption spectrum of HCN has previously been investigated photographically by Badger and Binder. Since their publication, plates have been available which are sensitive much further into the infra-red. The most recent Agfa plates have their maximum of sensitivity at 10600 A and have been used by us as far as 12300 A with a tungsten lamp or even 12900 A with the sun. We have now used these plates to investigate the infra-red absorption spectrum of HCN up to 12300 A. While Badger and Binder found only two very weak bands at 7912 and 8563 A we have found two rather strong bands at 10385 A and 11645 A which could be accurately measured and analysed. In adition we have found an interesting pressure effect on the line width. The whole infra-red spectrum of this molecule and the vibrational energy scheme has recently been discussed by Adel and Barker who have also measured several new bands in the far infra-red.

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

A Search for Dyson Spheres around Late-Type Stars in the Solar Neighborhood II

1997 ◽  
Vol 161 ◽  
pp. 707-709 ◽  
Author(s):  
Jun Jugaku ◽  
Shiro Nishimura
Keyword(s):  
Solar Neighborhood ◽  
The Sun ◽  
Late Type ◽  
Solar Type

AbstractWe continued our search for partial (incomplete) Dyson spheres associated with 50 solar-type stars (spectral classes F, G, and K) within 25 pc of the Sun. No candidate objects were found.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

Polar Magnetic Field Reversals of the Sun in Maunder Minimum

2000 ◽  
Vol 179 ◽  
pp. 193-196
Author(s):  
V. I. Makarov ◽  
A. G. Tlatov
Keyword(s):  
Magnetic Field ◽  
Maunder Minimum ◽  
The Sun ◽  
Annual Rings ◽  
Field Reversal ◽  
Polar Magnetic Field ◽  
Pine Trees ◽  
Using Data ◽  
Magnetic Field Reversal

AbstractA possible scenario of polar magnetic field reversal of the Sun during the Maunder Minimum (1645–1715) is discussed using data of magnetic field reversals of the Sun for 1880–1991 and the14Ccontent variations in the bi-annual rings of the pine-trees in 1600–1730 yrs.

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