Cometary spectra (Council report on the progress at astronomy)
in Monthly Notices of the Royal Astronomical Society (1943), 103Detailed reference viewed: 8 (1 ULg)
Tentative identification of the Herzberg bands of O2 in the ultraviolet spectrum of the night sky.
in Astrophysical Journal (1943), 97Detailed reference viewed: 8 (0 ULg)
Cometary emission spectra in the Visual Region.
Swings, Polydore ; ;
in Astrophysical Journal (1943), 98
A list of wave lengths of the emission features occurring in the region λ > 4800 has been compiled partly on the basis of previously published data but mainly from measurements of spectrograms of the ... [more ▼]
A list of wave lengths of the emission features occurring in the region λ > 4800 has been compiled partly on the basis of previously published data but mainly from measurements of spectrograms of the recent bright comets 1940c and 1942g obtained at the McDonald, the Mount Wilson, and the Dominion Astrophysical observatories. It is indicated that certain of the more prominent features behave, with respect to the comet's heliocentric distance, as emissions from polyatomic molecules would be expected to do. Comparison of the cometary spectrum with that of an oxyammonia flame leads to the suggested identification of a number of the emission features, among them the strong "λ 6300 group," as due to a dissociation product of ammonia, probably NH2. [less ▲]Detailed reference viewed: 12 (3 ULg)
Forbidden lines of ionized nickel in the spectra of bright-line stars
in Publications of the Astronomical Society of the Pacific [=PASP] (1943), 55Detailed reference viewed: 9 (0 ULg)
Edlén's identification of the coronal lines with forbidden lines of Fe X, XI, XIII, XIV, XV; Ni XII, XIII, XV, XVI; Ca XII, XIII, XV; A X, XIV
in Astrophysical Journal (1943), 98Detailed reference viewed: 8 (0 ULg)
The spectrum of Pleione
; Swings, Polydore
in Astrophysical Journal (1943), 97
The radial velocity of Pleione shows oscillations with a range of 10 km/sec and a period of about four months. The mean velocity is +5.5 km/sec. The spectrum of the shell, first discovered by McLaughlin ... [more ▼]
The radial velocity of Pleione shows oscillations with a range of 10 km/sec and a period of about four months. The mean velocity is +5.5 km/sec. The spectrum of the shell, first discovered by McLaughlin and Mohler in 1938, has gradually become stronger and now resembles the metallic spectrum of α Cygni. Dilution effects are conspicuous in the weakness of Mg II and Si II. Among the lines of ions having metastable lower levels, Ni II and Fe II became conspicuous in 1940, Ti II in 1941, and Mn II in 1942. This order of development is not consistent with the ordinary theory of ionization, and its explanation must be sought in the conditions of excitation of the metastable levels in the shell. The central intensities of the cores of the H lines are about 10 per cent—roughly one-half or one-third of the central intensities of the corresponding lines in α Cygni. This is explained as a consequence of the reduced re-emission which is thrown back within the shell into the emerging beam of radiation from the star. The metallic lines on the violet side of the Balmer limit and between the higher members of the series are relatively much stronger than in α Cygni. This is due to the semitransparency of the shell, on the one hand, and to the absence of Stark effect wings in the shell, on the other. [less ▲]Detailed reference viewed: 21 (1 ULg)
The Spectrum of a2 Canum Venaticorum.
; Swings, Polydore
in Astrophysical Journal (1943), 98
A new list of wave lengths containing 3107 absorption lines between λ 3087.9 and λ 4740.6 has been obtained from 28 spectrograms taken at the Mount Wilson and the McDonald observatories. Of these plates ... [more ▼]
A new list of wave lengths containing 3107 absorption lines between λ 3087.9 and λ 4740.6 has been obtained from 28 spectrograms taken at the Mount Wilson and the McDonald observatories. Of these plates, 18 were obtained with a dispersion of around 3 A/mm, while the other plates, used in the ultraviolet region, had 20 A/mm. The identifications are based upon all available laboratory material and show that all singly ionized rare earths which have been measured in the laboratory and which have a sufficient number of fines in the region covered by the stellar spectrograms are present. One doubly ionized rare earth, Ce III, is almost certainly present, and others may contribute to blends. The intensities of all rare-earth lines are variable in a period of 5.5 days and follow the pattern of the Eu II lines (designated as group A). The lines of Cr II and some other elements vary in the opposite sense (group B), while certain other lines—Si II, Mg II, etc.—do not appreciably change in intensity (group C). The radial velocities as measured from the lines of different elements also fall into three groups, designated as a, b, and c, which roughly correspond to the intensity groups A, B, and C. Group a, consisting of the rare earths and some other elements predominantly of low ionization potential, shows a shallow minimum of velocity at phase 4.5 days after maximum Eu II intensity and a sharp maximum of velocity at phase 1.5 days. Group b, represented by Cr II and some other elements, shows a velocity-curve with a double wave. The highest maximum is at phase 5.0 days and the deepest minimum at phase 0.7 day. Group c, consisting of Mg II, Si II, H, and Ca II, shows no appreciable variation. [less ▲]Detailed reference viewed: 20 (2 ULg)