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941.
942.
We present high-precision photometric observations of the transiting exoplanets HAT-P-40 b and HAT-P-51 b by the Rozhen 2-m telescope.The newly-observed transit of HAT-P-40 b is the first one with a complete curve.The orbital periods of the two targets were improved.We modeled the observed transits and found bigger stellar radii than those derived from the stellar models.The planet radii of HATP-40 b and HAT-P-51 b obtained from our transit solutions are bigger than the values calculated by the empirical relations for Jupiter-mass and Saturn-mass planets respectively.Their values reveal the highlyinflated nature of the two targets,especially that of HAT-P-51 b.We established that the best transit solutions correspond to a quadratic limb-darkening law.The fitted limb-darkening coefficients of HAT-P-40 are close to the theoretical ones while those of HAT-P-51 are a little different.The precise astrometric Gaia distances of the two targets are smaller by 6%–7%than the calculated values from the stellar models.We propose the Gaia distances to be used for improvement of the stellar models as well as for more reliable calculation of the parameters of the known exoplanets. 相似文献
943.
The short-periodic spectroscopic and photometric variations and the frequency ratio of 1:2 suggest the existence of a triple system for ET And, though some serious difficulties continue to exist in explaining all observational facts. Assuming a triple, the observable star is the primary of a very close, ellipsoidal binary system. Under this assumption the star cannot be a main-sequence B9 star as usually assumed. It should be a star located in the domain of the horizontal branch stars in the HR diagram possessing a thin and expanding envelope. Spektroskopische und photometrische Beobachtungen des variablen Sterns ET And wurden in den Jahren 1981/82 ausgeführt. Zusätzlich zu der bekannten periodischen Variation der Radialgeschwindigkeit von 48.308 Tagen, hervorgerufen durch einen Begleiter und der wahrscheinlich von der Rotation des Sterns herrührenden photometrischen Periode von 1.61883 Tagen, existieren weitere periodische Variationen. So variieren die Radialgeschwindigkeiten mit einer Periode von 0.1989 Tagen und die photometrischen Werte mit der Hälfte dieses Wertes, d. h. mit 0.0994 Tagen. Die Minima der Helligkeit koinzidieren mit den Extrema der Radialgeschwindigkeiten. Die Radialgeschwindigkeitskurve weicht etwas von der Harmonischen ab; die Werte steigen rascher an, als sie abfallen. Das gleiche Verhalten liegt auch für den entsprechenden Teil der Lichtkurve vor. Die kurzperiodischen spektroskopischen und photometrischen Variationen und das Frequenzverhältnis 1:2 legen die Existenz eines Dreifachsystems für ET And nahe, obwohl für die Erklärung aller Beobachtungswerte einige ernste Schwierigkeiten fortbestehen. Vorausgesetzt der Stern sei ein Dreifachsystem, dann ist der beobachtete Stern die Hauptkomponente eines sehr engen ellipsoidalen Systems und kann nicht ein Hauptsequenz-B9-Stern sein, wie allgemein angenommen wird. Vermutlich handelt es sich bei ET And um einen Vertreter der Gruppe der Horizontalsterne im HR-Diagramm, welcher noch eine dünne, expandierende Hülle besitzt. 相似文献
944.
945.
946.
P. Wagner 《International Journal of Earth Sciences》1925,16(4):321-321
Ohne Zusammenfassung 相似文献
947.
948.
Some recent finds from two working pits in the outwash sands of the Cheshire Plain are recorded. The opportunity is taken to discuss the dating and ecology of the fauna in relation to past and present theories of environment in the late Pleistocene, and their relationship to the fauna of the Macclesfield New Cemetery Beds. 相似文献
949.
H.P. Laubscher 《Tectonophysics》1977,37(4):337-362
The term “folding” encompasses a wide range of processes, most of which are poorly understood. Jura folds, though comparatively simple, have developed by a superposition of different types of instabilities both in space and time. They are never periodic and sinusoidal and are more realistically approximated by kink bands with rounded hinges. Thrusting and kinking instabilities had closely similar thresholds, with kinks usually following and deforming thrusts. An analysis of embryonic folds shows that instabilities in the sedimentary cover were initiated primarily at inherited flaws of the basal décollement layer. They thence spread upward, often following stratigraphically higher incompetent layers in secondary décollement and there nucleating secondary instabilities before reaching the surface (disharmonic folding). Embryonic folds thus are usually narrow, emanating from secondary décollement layers that are connected with the basal décollement zone by thrusts nucleated at inherited obstacles. These are eventually overcome, permitting basal décollement to coalesce with kinking instabilities that grow downward from nuclei in higher décollement intervals. In this way folds centered in the basal décollement layer, and consequently of normal width, may be superposed on the narrow embryonic folds. The sequence and importance of the different elements may vary from place to place to result in a vast catalog of fold shapes. 相似文献
950.
The northern limits of glacial lake Algonquin in upper Michigan 总被引:1,自引:0,他引:1
Richard P. Futyma 《Quaternary Research》1981,15(3):291-310
A number of ancient shorelines formed by late-Pleistocene proglacial lakes have been found in eastern upper Michigan. These shorelines delimit several water planes, the uppermost of which is correlated with the Main Lake Algonquin stage. This correlation is based on the continuity of the highest water plane with Main Algonquin shorelines in Wisconsin and Ontario, the strength of the shoreline features, its altitudinal relationship with lower water planes, and a reinterpretation of radiocarbon dates from the Sault Ste. Maria area. The isobases of this water plane have a bearing of S75°E. At the time of the maximum extent of Lake Algonquin, ca. 10,600 yr B.P., its northern, ice-limited border lay along the Munising moraine, the northernmost of the two main morainic systems of eastern upper Michigan. This interpretation lends support to the idea of a period of slow deglaciation from ca. 11,000 to 10,000 yr B.P. An ice lobe occupied the central Lake Superior basin until early Holocene time. Radiocarbon dates on wood found beneath till or outwash at several sites indicate a minor ice readvance from the central Lake Superior basin ca. 10,000 yr B.P. If true, this would have prevented the development of the post-Duluth series of glacial lakes in the western Lake Superior basin until ca. 9900 yr B.P., well after the end of the main Lake Algonquin stage. 相似文献