Sur la brillance de la lune eclipsee

Sommaire L'excès de luminosité de la Lune eclipsée est attribué à l'impact de la poussière cosmique magnétique environnant la Lune, concentrée et guidée par la queue géomagnétique. Ce mécanisme rend compte de la lenteur du refroidissement du sol lunaire durant les éclipses. La règle de Danjon est attribuée à l'extension variable de cette queue en fonction de l'activité solaire, celle-ci n'atteignant plus la Lune à l'époque des minimums d'activité.     

Theorie analytique programmee de la libration physique de la lune

Résumé La rotation de la Lune autour de son centre de gravité est traitée par une méthode analytique, en tenant compte de son mouvement orbital. On développe une théorie Hamiltonienne en utilisant les variables d'Andoyer et l'on démontre que les écarts, purement périodiques, à trois relations de résonances similaires aux lois de Cassini, sont les variables canoniques du problème. Le potentiel est exprimé dans ces nouvelles coordonnées et l'Hamiltonien est développé jusqu'au deuxième degré en les petites variables. Un système d'équations donne le vrai centre de libration qu'on trouve proche du centre défini par les lois de Cassini. Un second système, résolu par un processus d'iterations, donne les séries de la libration, analytiques par rapport aux constantes du potentiel de la Lune et trigonométriques en les arguments de Delaunay. La question de convergence est brièvement abordée, mais sans démonstration.

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The rotation of the Moon about its center of mass, taking into account the orbital motion, is treated analytically. A Hamiltonian theory is developed in terms of the Andoyer variables. The periodic parts of departures from three resonances, equivalent to Cassini's laws, are found to be the canonical variables of the problem. The potential is expressed as a function of these new coordinates and the whole Hamiltonian is developed to the second degree in these small variables. One system of equations gives the real center of libration which is found to be near the center defined by Cassini's laws. A second system solved by iterations, gives the libration as analytical series in the constants of the Moon's potential, and trigonometric series in Delaunay arguments. The question of convergence is briefly exposed without any demonstration.

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Ce travail a été soutenu par une bourse du Centre National d'Etudes Spatiales.     

Étude de la position de la lune sur champ stellaire

In order to improve our knowledge of the astronomical constants, great interest must be paid to accurate positions of major planets and their satellites. Likewise, accurate astrometry of the Moon on stellar background is essential to determine the ephemeris time. Both programs are pursued by Bordeaux Observatory.     

Analyse photométrique de la pénombre pendant les Éclipses de lune

Sommaire L'analyse photométrique de la pénombre pendant 21 éclipses de 1921 à 1968 sur la base d'un matériau homogène d'observations revèle des anomalies explicables par la luminescence du sol lunaire excitée par les radiations UV-X solaires dont les sources se situent dans la basse couronne et au-dessus des plages K-3. L'influence de la haute atmosphère terrestre se manifeste au bord de l'ombre.

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Photometric analysis of the penumbra during 21 eclipses between 1921 and 1968 based upon the homogeneous observational material reveals some anomalies which may be explained by the lunar luminescence excited by UV-X solar radiations whose sources are located in the low corona and above the K-3 plages. The influence of the terrestrial upper atmosphere is detectable on the border of the umbra.

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Ex-astronome à l'Observatoire de Bordeaux.

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En congé de l'Institut Astronomique de l'Académie des Sciences, Prague.     

Détermination de la position du cratère mösting a À partir de plaques photographiques de la lune sur fond d'étoiles

The reduction of 126 photographic plates from the Moon on stellar background, gives a new determination from the Mösting A coordinates with respect to the Lunar inertial system. This determination is based on: the Eckhardt theory for the physical libration, and the ephemeride (j = 2) derived from Brown's theory. The S.A.O. star catalog for the star positions, is used for this reduction.     

Relation entre l'equation de szebehely du probleme inverse de la mecanique et la theorie de hamilton-Jacobi

For any family of orbits having the same energy constant and orthogonal to a surface, we show the equivalence of Szebehely's equation of the inverse problem and the major result of Jacobi's theorem i.e. there exists a velocity potential.      

Analyse photometrique de l'eclipse de lune du 16 Septembre 1978

Sommaire La discussion de l'éclipse du 16.IX.1978 basée sur la comparaison des mesures photométriques de l'ombre avec la théorie basée sur l'atmosphère terrestre (pure). Les différences de la densité observée et de la densité calculée sont partiellement dues à l'absorption dans la couche d'ozone, mais le reste doit être attribué à l'absorption dans le milieu situé au-dessus de la couche d'ozone.

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The discussion of the eclipse 1978.IX.16 based on the comparison of the photometrical measurements of the shadow with the theory based on pure terrestrial atmosphere, is presented. The differences between the observed and computed density of the shadow are partly due to the absorption in the ozone layer, and the remainder can be attributed to the absorbing medium above the ozone layer.

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Décédé subitement le 2 décembre, 1979.     

Analyse de l'Ombre extérieure pendant les Éclipses de lune

Sommaire L'analyse photométrique de l'ombre extérieure pendant 20 éclipses de 1921 à 1968 sur la base d'un matériau homogène d'observations révèle l'existence de la luminescence du sol lunaire excitée par les radiations corpusculaires solaires. L'influence de la haute atmosphère terrestre vers 25 km d'altitude se manifeste au bord de l'ombre.

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Photometric analysis of the peripheric umbra during 20 eclipses between 1921 and 1968 based upon the homogeneous observational material reveals the existence of the lunar luminescence excited by solar corpuscular radiations. The influence of the terrestrial upper atmosphere at about 25 km height is detectable on the border of the umbra.

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En congé de l'Institut Astronomique de l'Académie des Sciences, Prague.     

Etoile centrale et condition d'ionisation de l'enveloppe de la nova Delphini 1967

After correcting the observed flux of the forbidden lines for the supplementary reddening (due to the circumstellar envelope), we have recalculated the electron density and temperature of the envelope of the Nova. We have determined the temperature and radius of the Nova and obtained values of 1.03×10⁵ K, 1.15×10⁵ K and 1.21×10⁵ K for the temperature and values of 8.49×10¹⁰ cm, 4.32×10¹⁰ cm and 1.18×10¹⁰ cm for the radius of the Nova for 1968, 1969 and 1970, respectively. Using the temperature and radius of the Nova the electron density and temperature of the envelope and the degree of ionization, we have determined the optical depth of the envelope in the Lyman continuum, and found that it is of the order of 10 during the nebular stage.Considering the stratification of the envelope in different regions of ionization, we have determined the radius of the inner and outer edge and the electron temperature of every region. We found that the electron temperature of the inner part of the envelope is at least three times greater than that of the outer part. The variation of electron temperature as a function of the radius of the ionization region considered shows an abrupt increase of theT _e whenR/R _out(env) is between 0.44 and 0.54.     

Irradiation et pré-irradiations de la brèche 14307

Sample 14307,30, a gas-rich breccia (Group 1 of Warner, 1972) has been studied by coupling track method and light noble gas isotopic analysis. The breccia is made of a glassy dark matrix with embedded millimeter to sub-millimeter sized angular ligth xenoliths. These ones are breccia fragments of higher grade metamorphic facies (Group ? 2). A lighter strata (～ 0.5 cm thick) intersects the dark matrix. Noble gas analysis have shown the dark matrix (³⁶Ar = 5.4 × 10^?4 cc STP/g) to be enriched in solar type gases with respect to the light fractions (³⁶Ar ? 2.2 × 10^?4 cc STP/g). Themean value of the bulk ‘exposure age’ for different samplings is 180 ± 20 × 10⁶ yr, as calculated from spallogenic³He,²¹Ne and¹²⁶Xe contents, using our data and those of Bogard and Nyquist (1972). After appropriate correction for radiogenic⁴⁰Ar, the ratio⁴⁰Ar_exc/³⁶Ar_tr is about 5. A total of 390 crystals coming from 11 locations either in the dark matrix, the lighter strata or a light xenolith (0.25 cm diam), have been studied by track analysis using optical and scanning electron microscopy. 181 crystals were thoroughly investigated by means of the latter technique. The following results were obtained:

1. 72 crystals (70-300µm diam) from one location (No. 12) in the matrix show aminimum track density distribution spreading over 3 orders of magnitude (from 2 × 10⁶ up to 2 × 10⁹ cm^?2). The spectrum has at its lower edge a well defined peak (～ 50% of total crystal number) around 3 × 10⁶ cm^?2). Grains with track density variations over a factor of 3 have a low abundance as compared to average lunar soils. Moreover the mineralogy of this location is peculiar due to its large abundance in orthopyroxenes. Considering the lower edge of the track density distribution amaximum surface residence time of 5 × 10⁶ yr can be set for rock 14307 in itspresent shape;
2. 11 feldspars (1-15µm diam) and 22 clinopyroxenes (70-130µm) have been studied in the light xenolith. All crystals have minimum track densities larger than 10⁸ cm^?2. No spatial variation of track-densities (2.5 ± 0.5 × 10⁹ cm^?2) were found in feldspars inside a millimeter-sized polished section. Clearly these tracks were not acquired by an irradiation of the xenolith as an individual entity, but survived its own formation as a breccia of Group 2. Therefore, solar energetic iron particle tracks have not been erased despite a complex mechanical and thermal history involved by two subsequent brecciation processes;
3. in the 10 other locations, crystals (70-200µm diam) either from the dark matrix or the lighter strata show a significant departure from the pattern observed in lunar soils; namely:

1. the minimum track density distribution is strongly peaked at high values (～ 1-4 × 10⁹ cm^?2) for ～ 95% of the crystals, the remaining ～ 5% having low-values (0.2-1 × 10⁷ cm^?2);
2. the abundance (2%) of crystals with track density variation over a factor of 3 is about one order of magnitude less than in average lunar soils;
3. the magnitude of track density gradients within single crystals is small. In fact, thelargest track density variation versus depth found can be described by the relation? α D^?0.5, in contrast with soil grains which generally exhibit a variation of the form? α D^?1.1±0.4.

The above observations imply that the peculiar irradiation characteristics of these fossilized soils are more likely to be attributed to some wide scale process rather than to some accidental or local phenomena. Attempts to account for these findings by present solar VH particle flux and energy distribution (as determined by Crozaz and Walker, 1971; Fleischeret al., 1971b; Priceet al., 1971), current estimates of lunar fine scale erosion, accumulation and turn-over rates, have proven essentially negative. The bulk ‘exposure age’ of the breccia, rather low by lunar soil standards, makes things even worse. For lack of any better explanation, the above observations could be more easily understood by postulating a higher flux (by factors from ～ 10 up to 200) and a harder energy spectrum (at least for particles with rigidity less than 0.3 GV) for the solar cosmic rays at the time the constituents of the breccia were part as loose grains of the lunar regolith.     

Analyse photométrique de l'ombre intérieure pendant les Éclipses de lune

Sommaire On explique les sursauts de lumière observés à plusieurs reprises dans l'ombre intérieure par l'effet de la luminescence lunaire. On prend la position vis-à-vis de récents examens au laboratoire des échantillons lunaires en ce qui concerne la luminescence.

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The surge of light observed sometimes in the central parts of the umbra is explained by the lunar luminescence. The position is takenvis-à-vis of recent examinations in the laboratory of lunar samples in the relation with the lunar luminescence.

     

Evolution du spectre de la Nova Delphini 1967 en 1971 et 1972

Continued spectroscopic observations of Nova Del 67 during 1971 and 1972 show a general decrease of the nebular and coronal emission with respect to the local continuum. The continuous spectrum exhibits a strong Balmer emission (figure 1). Equivalent widths of Hi, Hei, Heii, Oi, [Oi], Oii, [Oii], Oiii, [Oiii], Niii, [Sii], [Aiii], [Neiii], [Nev], [Fevi], [Fevii], [Fex], [Fexi], [Fexiv], [Nixvi], [Nixv] are listed in tables 1 and 2.Figures 5 to 10 show several line profiles, which can be interpreted in terms of a model proposed by Hutchings (1972). Kinematical properties of the nova envelope do not seem to have changed in the 1968–1972 time interval. However, a study of the [Oiii] (4959 Å) line indicates that the physical conditions in the polar blobs in 1972 (T _e=10 660 K,N _e=5,5×10⁵ cm^–3) are different from those prevailing in equatorial rings (T _e=9×100 K,N _e=7×10⁵ cm^–3).

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Le matérial d'observation utilisé pour cette étude a été obtenu à l'aide de téléscopes de 120 cm, 152 cm et 193 cm de l'Observatoire de Haute-Provence (CNRS).     

Gradient de densité et température dans la basse couronne

Résumé On considère souvent que le milieu coronal est en équilibre hydrostatique si bien que l'étude de la distribution verticale de la matière est censée donner une bonne estimation de la température coronale (Billings, 1966). De fait, le gradient vertical de densité observé dans la basse couronne (altitudes inférieures à 300 000 km) où l'effet du vent solaire est peu important conduit à une température hydrostatique de 1 500 000 K en moyenne, en assez bon accord avec les déterminations fondées sur l'étude du rayonnement radioélectrique et sur celle de l'ionisation. Il semblerait néanmoins souhaitable de chercher à préciser cette concordance moyenne en comparant dans le détail les variations de la température coronale et celles du gradient vertical de densité pour voir si l'hypothèse de l'équilibre hydrostatique est partout vérifiée.Cette comparaison ne peut être tentée qu'à partir d'un jeu d'observations suffisamment variées pour que l'on puisse déterminer de façon indépendante la densité et la température dans une même région de la couronne: un tel matériel est disponible grâce aux observations coronales effectuées entre 1967 et 1969 à l'Observatoire du Pic du Midi, qui comportent notamment, pour 81 journées d'observations, (a) la mesure de l'intensité des raies 5303 Å et 6374 Å, à 1 du bord, tous les 5° autour du Soleil (b) la mesure de la brillance de la couronne K pour les mêmes angles de position, à 15 et à 5 du bord. Sans discuter ici des caractéristiques propres à ces deux catégories d'observations, qui ont déjà été décrites dans d'autres publications, nous allons chercher dans ce travail à les utiliser pour mettre à l'épreuve la validité de l'hypothèse de l'équilibre hydrostatique dans la basse couronne.

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The observations performed at the Pic du Midi Observatory with a K-coronameter at different altitudes above the solar limb allow us to compute the vertical density gradient of the corona, therefore giving the value of the hydrostatic temperature T _h computed under the assumption of hydrostatic equilibrium in the lower corona. We compare T _h with the ratio r = I ₅₃₀₃/I ₆₃₇₄ of the intensities of the green and the red coronal lines observed at the same position angle and on the same day: r is expected to yield the proportion of cold regions and hot regions along the line of sight under study. As a matter of fact no relation appears between individual values of T _h and r nor between averaged values of T _h and r (Figure 1). In a second step we compute the 5303 Å emission which should be observed, for selected position angles where 6374 Å emissions are faint, making use of the electron density values which can be deduced from the K corona observations. The ratio q = (I ₅₃₀₃) obs/(I ₅₃₀₃) calc of observed to computed 5303 Å intensities should depend upon the corona temperature according to the ionization theory. But again, we do not find the expected relation since Figure 2 displays only a large scatter of points. We conclude that large deviations to hydrostatic equilibrium probably occur in the corona but it is still possible that the presence of arch structures in the lower corona makes it unrealistic to interpret a ratio of intensities integrated along different lines of sight in term of a regular density gradient, although this procedure has been universally used up to now.

     

Theorie generale planetaire etendue au cas de la resonance et application au systeme des satellites galileens de Jupiter

We consider a system of planets defined by a given distribution of mean mean motions and masses: we represent the osculating elliptic elements of their heliocentric orbits by quasi-periodic functions of time, through a method adapted to the commensurability case; these functions are the sum of the general solution of a critical system, expressed in long-period terms, and of a particular solution. As in the B. Brown's method (applied to the galilean satellites), the critical system contains the secular terms, the longperiod terms (great inequalities), and the resonant terms; the particular solution consists of short-period terms only, whose amplitude is an explicit function of the solution of the critical system.If all the long-period terms in the critical system are harmonic of one fundamental term, we can perform a simple change of variables which transforms the critical system in an autonomous one, and thus we reduce the resolution to an eigenvalue problem. Applying that to the galilean satellites of Jupiter and neglecting the solar perturbations, we obtain a differential system with constant coefficients, whose linear part concerns all the variables (including the major-axes and the mean longitudes) and gives, as a first approximation, the great inequalities, the free oscillations and the libration; nevertheless this solution agrees already with known results, but should be improved by taking into account the non-linear parts and the solar terms in a new approximation.

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Proceedings of the Conference on Analytical Methods and Ephemerides: Theory and Observations of the Moon and Planets. Facultés universitaires Notre Dame de la Paix, Namur, Belgium, 28–31 July, 1980     

Raies nébulaires et coronales dans le spectre infrarouge de la Nova Delphini

Nova Delphini 1967 has been observed in the red and photographic infrared at the Haute-Provence Observatory from September 7 to November 12, 1968. Dispersions range from 230 Å/mm to 4 Å/mm. The slope of the continuous spectrum in the region 1.3–1.7 ^–1 leads to a gradient of 3.06, which did not appear to vary during the observing period. This gradient is, however, very different from the value 1.71 measured on plates secured in August 1968. Lines ofHi, Hei, Heii, Feii,Oi,Cii and forbidden transitions due toOi,Oii, Fevii, Fex, Fexi,Siii,Aiii,Av,Axi and Nixv have been identified. Their intensities at various dates are given in Table II. Line profiles could be measured for a few lines taken on a 39 Å/mm spectrogram on October 3. Hei 6678 and 7065 are displayed on Figures 2 and 3. Figure 4 gives the [Oii] doublet at 7319–7330, while the H profile, obtained on October 4 can be seen on Figure 5. The line extends over more than 45 Å and narrow absorptions are seen at 6551.05; 6555.75; 6563.15; 6571.49; 6574.45. Due to the absence of published data on radial velocities of absorption lines in the visible spectrum at that time, it is not possible to give a clear identification for these features. Some of them may belong to H, while others are probably due to metals.     

Sur l'effet d'une correction de la constante de la précession

Sans résuméPresented at IAU Colloquium No. 9, The IAU System of Astronomical Constants, Heidelberg, Germany, August 12–14, 1970.     

Etude de la collision triple

Résumé Ce sont principalement les investigations de Cartan, Madame Losco et Mac Gehee qui ont inspiré le travail qui suit. Un changement de variables simple et spécialement adapté au problème de la collision triple conduit de façon naturelle à une étude directe et intuitive du phénomène.

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This work paper has been mainly inspired by the investigations of Cartan, Madame Losco and McGehee. A simple change of variables that is especially adapted to the problem of triple collision leads in a natural way to a direct and intuitive study of the phenomenon.

     

La lune mange-t-elle les couleurs?

The hydrogen radicals play an important role in the photochemistry of the troposphere of the Earth. The chemistry of OH, HO₂ and H₂O₂ is linked directly to the photodissociation of O₃ through the production of O(¹D). Gaseous H₂O₂ (hydrogen peroxide may be removed by heterogeneous reactions involving aerosols and liquid water. During the day and the night the solubility of ambient H₂O₂ in water is estimated and the oxidant capacity of H₂O₂ may explain the bleaching properties of the dew used in the past. This phenomenon may also explain some old maxims concerning the properties of the Moon's light to corrupt colors.     

Photometrie photographique de la couronne solaire

Solar Physics - A series of plates of the solar corona were obtained during the total solar eclipse of July 10th, 1972 near Anadyr (U.S.S.R.) using a standard eclipse coronagraph of Ø = 20 cm...