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See detailThe Spectra of Comets 1950b (Minkowski) and 1951a (Pajdusakova).
Swings, Polydore ULg; Page, Thornton

in Astrophysical Journal (1952), 115

The spectrum of Comet 1950b at heliocentric distance 2.65 A.U. shows a strong solar continuum concentrated in the nucleus and CN emission over a coma forty times larger. Comet 1951a at heliocentric ... [more ▼]

The spectrum of Comet 1950b at heliocentric distance 2.65 A.U. shows a strong solar continuum concentrated in the nucleus and CN emission over a coma forty times larger. Comet 1951a at heliocentric distance 0.91 A.U. is very unusual in showing a strong nuclear continuum and extremely weak CN emission over a coma only eight times larger than the nucleus. The former seems normal for a comet distance from the sun; the latter is probably a "fresh" comet, newly arrived near the sun from the swarm of cometary material postulated by Oort at the outer confines of the solar system. [less ▲]

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See detailThe Spectrum of Comet Bester (1947k).
Swings, Polydore ULg; Page, Thornton

in Astrophysical Journal (1950), 111

An extensive program of observations, planned in advance, was carried out during the predicted return of Comet Bester in March and April, 1948, as the comet receded from heliocentric distance 0.8 A.U. to ... [more ▼]

An extensive program of observations, planned in advance, was carried out during the predicted return of Comet Bester in March and April, 1948, as the comet receded from heliocentric distance 0.8 A.U. to 1.55 A.U. The eighteen spectra obtained extend over various parts of the observable region from λ 3070 to λ 8760, most of them from λ 3500 to λ 6800 on grating dispersion. These, together with seventeen direct photographs, provide virtually a continuous record of changes in the comet during the observing period. Since the slit of the spectrograph was oriented along the tail, extending about 4.5 minutes of arc from the nucleus, our spectrograms record the extent of the various molecular bands away from the nucleus. Based on this material and on observations of other comets, the following topics are discussed: a) Variations with heliocentric distance, r.-In Comet Bester the ratios CN/C2, λ 4050/CH, λ 4050/CN, λ 4050/C2 and probably OH/NH all increase regularly with increasing r. No flares or sudden changes in spectrum were observed. b) Extent of bands from the nucleus.-CO+, N2+, λλ 3378, 3509, and 3674 are found exclusively in the tail; CN, C2, NH, OH, λ 4050, and NH2 follow in order of decreasing extent from the nucleus. c) The far ultraviolet region.-The ratio OH/NH varies from comet to comet, being somewhat less than unity for Comet Bester, greater than unity for Comet 1941d, and much less for 1947n and 1941c, which are in other respects comparable. In Comet Bester the OH bands have a peculiar rotational distribution, probably due to the fluorescence mechanism. d) The photographic regions.-Twenty lines in the "λ 4050 group" behave in Comet Bester as if they originate from one molecular species. e) The red and infrared regions.-The existence of bands (tentatively identified with the "red system" of CN) at λ 7906 is confirmed, and other bands of the "red system" at shorter wave lengths tentatively identified. A number of other faint maxima between λ 7000 and λ 8700 are noted. f) The spectrum of the tail.-Nine bands of the CO+ "comet-tail system" are recorded, the (3, 0) band being abnormally strong. Four bands of the "Baldet-Johnson system" of CO+ are observed. Tentative identifications of the "β system" of NO and the "Schumann-Runge system" of O2 are noted. The strong emissions at λλ 3378, 3509, and 3674 are identified with CO2+, the third ionized molecule to be identified in comet tails. A summary of identifications and conclusions is given at the end of the paper. [less ▲]

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See detailThe Spectrum of Comet 1947n.
Swings, Polydore ULg; Page, Thornton

in Astrophysical Journal (1948), 108

The spectrum of Comet 1947n has been observed from heliocentric distance r = 0.504 to r = 1.135 between λ 3000 and λ 8900. The OH band is unusually weak relative to NH. The (0, 0) band of CN reveals a ... [more ▼]

The spectrum of Comet 1947n has been observed from heliocentric distance r = 0.504 to r = 1.135 between λ 3000 and λ 8900. The OH band is unusually weak relative to NH. The (0, 0) band of CN reveals a complex rotational structure due to fluorescence, similar to that observed in previous comets. Features appearing within the Swan bands are described and discussed. The red region is mainly due to NH2. Two intense infrared emissions have been found for the first time at λ 7906 and λ 8106. A detailed discussion seems to indicate that they may be attributed to the red system of CN. This CN emission in the infrared does not result from fluorescence but probably from the photodissociation of a parent-molecule. No atomic lines have been found other than the D lines of Na. The two components of the nucleus reveal exactly the same spectrum. [less ▲]

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