The quenching of resonance radiation and the breadths of absorption-lines

1926 ◽  
Vol 23 (1) ◽  
pp. 78-84 ◽  
Author(s):  
R. W. Ditchburn
Keyword(s):  
Phase Difference ◽  
The State ◽  
Spectral Lines ◽  
Emission Lines ◽  
Absorption Lines ◽  
Total Probability ◽  
Absorption And Emission ◽  
Arbitrary Phase ◽  
Independent Probability ◽  
As If

In a paper by Slater a new theory of radiation is discussed and the following explanation of the breadths of spectral lines is given: “An atom in the ith. state has a probability Pi of suffering in unit time a transition. Thus there is a probability Pi that the vibrations of each of the oscillators will simultaneously cease. But we shall assume that, in addition to this probability Pi of ceasing its oscillation altogether, each oscillator has also an independent probability Pj of suffering an interruption in which it ceases its oscillation as if it were leaving the state, but immediately begins again as if it were entering the same state” (i.e. with an arbitrary phase difference). “This term Pj is the same as the probability that an atom in the jth state will leave that state.” The total probability of interruption of vibration is thus (Pi + Pj) which is symmetrical with regard to the two end states. This makes the breadths of absorption and emission lines equal and so satisfies Kirchhoff's law.

scholarly journals The binary orbit of HD 92740

1979 ◽  
Vol 83 ◽  
pp. 291-295
Author(s):  
Virpi S. Niemelä
Keyword(s):  
Observational Data ◽  
Orbital Motion ◽  
Radial Velocities ◽  
Emission Lines ◽  
Absorption Lines ◽  
Balmer Series ◽  
Absorption And Emission ◽  
Carina Nebula ◽  
Binary Orbit

HD 92740 is a star located in the Carina nebula showing a Wolf-Rayet spectrum of type WN7. Faint absorption lines of the upper Balmer series of hydrogen, and also of the Pickering series of Hell are present in the spectrum, in addition to the WN emissions. Although absorption lines present in a Wolf-Rayet spectrum are generally assumed to arise in a companion OB star, a previous study (Niemelä 1973) of the radial velocities of HD 92740 showed that the absorption and emission lines followed the same orbital motion. Subsequent spectral observations of this star have been carried out at the Cerro Tololo Inter-American Observatory, Chile, and at the Córdoba Observatory, Argentina, during four years; the observational data are listed in Conti, Niemelä and Walborn (1978). These observations showed that the true period is 8 times longer than the initially derived period of 10 days, and that doubtlessly the absorption lines belong to the WN star.

scholarly journals HD 192641 and HD 193077: Two Single, Hydrogen-Rich Wolf-Rayets?

1980 ◽  
Vol 88 ◽  
pp. 187-191
Author(s):  
Philip Massey
Keyword(s):  
Absorption Spectrum ◽  
Mass Loss ◽  
Stellar Wind ◽  
Binary Systems ◽  
Roche Lobe ◽  
The Other ◽  
Emission Lines ◽  
Absorption Lines ◽  
Absorption And Emission ◽  
Complete Story

As recently as six years ago it was generally agreed that all Wolf-Rayet (WR) stars were the product of mass loss induced by Roche lobe over-flow (RLOF), and that thus they were all members of binary systems. In particular, the presence of absorption lines in the spectrum of a WR star was taken as a definitive indicator that the star was a binary, as it was well known that emission alone (other than the absorption present in P Cygni profiles) was a WR characteristic. However, Niemela (1973) showed that in the WN 7 binary HD 92740 that the absorption and emission lines move in phase, proving that in at least one case the absorption spectrum originates in the WR star itself. Conti (1976) has meanwhile suggested that WR stars could form by mass loss due to a stellar wind rather than RLOF. Obviously it is well worth examining the belief that all (or even most) WR stars are binaries. The currently popular feeling is that the late WN stars (WN 7, 8, and 9) are the only possible exceptions to the traditional picture, while the members of the other subclasses are all hydrogen-poor and probably members of binaries. I hope to convince you today that this is not the complete story.

BLUESHIFTS IN ABSORPTION LINES OF QUASI-STELLAR OBJECTS?

2001 ◽  
Vol 10 (04) ◽  
pp. 443-464 ◽  
Author(s):  
D. BASU
Keyword(s):  
Emission Spectrum ◽  
Spectral Lines ◽  
Emission Lines ◽  
Absorption Lines ◽  
Absorption System ◽  
Stellar Objects ◽  
Quasi Stellar Objects ◽  
Ejection Mechanism

Possibility of misidentification of emission lines of QSOs and thereby missing detection of blueshifts have been suggested and demonstrated in literature. It is shown here that absorption lines observed in the spectra of QSOs may also have been misidentified. Plenty search lines are available at higher wavelengths (red/IR regions) for identification with observed absorption lines, although lines from lower wavelengths (UV/blue regions) are always considered for identification. Re-examination of the published spectra of ten QSOs shows that the observed absorption lines can be interpreted as blueshifted, with same or better accuracy and sometimes more convincingly than redshifts. Objects on the sight line are identified with same emission blueshift as the blueshift of the absorption system of the QSO, the emission spectrum of the QSO itself being of course interpreted as blueshifted as well. It is proposed that the absorbers are probably linked with the QSO either physically or tidally/gravitationally as a result of some ejection mechanism. The observed blueshifts of spectral lines in emission and absorption can be explained in a model comprising of multiple expanding universes.

Constantine as a ‘Bishop’

1947 ◽  
Vol 37 (1-2) ◽  
pp. 127-131 ◽  
Author(s):  
W. Seston
Keyword(s):  
Sixteenth Century ◽  
The State ◽  
Obiter Dictum ◽  
The Church ◽  
As If

The author of the Vita Constantini (traditionally and persistently identified with Eusebius, despite the silence of St. Jerome), tells us that Constantine ‘at a banquet he was giving to the bishops declared that he too was a bishop. He added these words which I heard with my own ears: ἀλλ᾽ ὑμεῖϛ μὲν τῶν εἴσω τῆϛ ἐκτὸϛ ὑπὸ θεοῦ καθεσταμένοϛ ἐπίσκοπϛ ἂν εἴην ’.In attempts to define the relations between the first Christian emperor and the Church, no phrase is more frequently quoted than this obiter dictum. In the sixteenth century the French scholar Henri de Valois rendered τῶν ἐκτόϛ as if it were the genitive of τὰ ἐκτόϛ, and since then it has been the practice to regard Constantine as an ‘évèque du dehors’: the Emperor either exercised episcopal functions though not consecrated, or supervised mundane affairs (that is, the State), after the fashion of a bishop, or else held from God a temporal commission for ecclesiastical government, the bishops retaining control of dogma, ethics and discipline. Each of these three distinct interpretations is equally admissible.

‘Hebrew Tarzans’ from Arthur Koestler's Thieves in the Night to Netflix and Fauda

2021 ◽  
Vol 20 (1) ◽  
pp. 45-61
Author(s):  
Jeremy Salt
Keyword(s):  
The State ◽  
Central Elements ◽  
Four Books ◽  
Letting Go ◽  
Core Elements ◽  
Occupied Territories ◽  
As If

Core elements of Zionist propaganda justifying the colonisation of Palestine are exploited again in the four books critiqued in this article ( Thieves in the Night; Promise and Fulfilment. Palestine 1917–1949; Exodus; and The Haj). For propaganda to be viable, however, it has to be adapted to changing circumstances. Recent Israeli television dramas such as Fauda (Chaos) have realigned images without letting go of the central elements in the propaganda war. In Fauda, Israeli killings in the occupied territories are virtually advertised, as if the state wants viewers to see what it is capable of doing in the name of combatting ‘terrorism’.

Playing through the Apocalypse: Preparing Children for Mass Disasters in Japan and Chile

2021 ◽  
Vol 33 (2) ◽  
pp. 239-259
Author(s):  
Chika Watanabe
Keyword(s):  
Disaster Preparedness ◽  
Nonprofit Organization ◽  
The State ◽  
Ethnographic Research ◽  
Government Officials ◽  
State Actors ◽  
Mass Disasters ◽  
As If

Abstract There is a growing trend to prepare children for future disasters. A Japanese nonprofit organization has developed an event called Iza! Kaeru Caravan, which includes games that teach children and their families how to survive disasters, from earthquakes to floods. Many disaster experts and government officials from other countries have now implemented the Caravan in their own contexts. Based on ethnographic research in Japan and Chile, this article shows how playful methods in disaster preparedness orient children, and by proxy their families, to accept an apocalyptic future, helping the neoliberal state buy time. Advocates of disaster preparedness in Japan and Chile accept that state actors will not come immediately to the rescue. Playful methods mobilize children and their families to take responsibility for their own survival through the subjunctive work of the “as if.” Ambiguously positioned between fun and education, playful methods of preparedness command attention from children and adults—what I call “attentive play”—as they frame and reframe the games to figure out, “Is this play?” Ultimately, the article shows that attentive play buys time for the state to temporarily defer its responsibilities to citizens, but the ambiguity of play can also exceed its ideological effects.

scholarly journals Spectrophotometry of Supernovae

1974 ◽  
Vol 3 ◽  
pp. 533-544
Author(s):  
R. P. Kirshner
Keyword(s):  
Emission Lines ◽  
Absorption Lines ◽  
Spectral Energy ◽  
Line Profiles ◽  
Energy Distributions ◽  
Maximum Light ◽  
Balmer Lines ◽  
B Lines ◽  
Infrared Triplet ◽  
The Continuum

AbstractAbsolute spectral energy distributions for supernovae of both types I and II have been obtained. These observations demonstrate three facets of supernova spectra. First, both SN I’s and SN II’s have a continuum that varies slowly and uniformly with time, and which carries the bulk of the radiated flux at early epochs. Second, some lines in both SN I’s and SN II’s have P Cygni profiles: broad emissions flanked on their violet edges by broad absorptions. Third, some lines are common to SN I’s and SN II’s and persist throughout the evolution of the spectrum. The continuum temperatures for both SN I’s and SN II’s are about 10000 K at the earliest times of observation and drop in one month’s time to about 6000 K for SN II’s and about 7000 K for SN I’s. After several months, the continuum may cease to carry the bulk of the flux, which might be in emission lines, but continues to exist, as shown by the presence of absorption lines. The P Cygni line profiles indicate expansion velocities of 15000 km s-1 in SN II’s and 20000 km s-11 in the SN I 1972e in NGC 5253. Line identifications for SN II’s include Hα, Hβ, H and K of Ca II, the Ca II infrared triplet at λ8600, the Na I D-lines, the Mg I b-lines at λ5174, and perhaps Fe II. The [O I] lines λλ6300, 6363 and [Ca II] lines λλ7291, 7323 appear after eight months. For SN I’s, the lines identified are H and K of Ca II, the infrared Ca II lines, the Na I D-lines, and the Mg I b-lines. There is some evidence that Balmer lines are present two weeks after maximum. The strong and puzzling λ4600 features drifts with time from λ4600 near maximum light to λ4750 after 400 days.

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