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1.
Pier Luigi Battistini Massimo Fracassini Laura E. Pasinetti 《Astrophysics and Space Science》1971,14(2):438-445
For the first time after Barbier and Chalonge's (1938, 1941) pioneering works, the variations of
b andD during the eclipse of a variable (RT Tau), have been observed. The observations have been performed at the Observatories of Jungfraujoch and Haute Provence with the photoelectric system in seven colors of Geneva (Golay, 1964; Hauck, 1968). The comparison between the observed curves ofD and the theoretical ones, provides the limb darkening coefficients; the same comparison between the observed
b (reddened) and theoretical ones (not reddened) together with that ofD, points out some anomalies of the variable RW Tau.
Sommario Per la prima volta, dopo i primi lavori di Barbier e Chalonge (1938, 1941), sono state osservate le variazioni di b eD durante l'eclisse di una variabile (RW Tau). Le osservazioni sono state fatte agli Osservatori della Jungfraujoch e di Haute Provence col sistema fotoelettrico in sette colori di Ginevra (Golay, 1964; Hauck, 1968). Il confronto fra le curve osservate e teoriche diD, fornisce i coefficienti di oscuramento al bordo; lo stesso confronto fra i b osservati (arrossati) e quelli teorici (non arrossati) unitamente a quello delleD mette in evidenza alcune anomalie della variabile RW Tau.相似文献
2.
Massimo Fracassini Paola Maggi Laura E. Pasinetti 《Astrophysics and Space Science》1986,128(2):363-368
The results of research on pairs of PSR which were possibly components of disrupted binaries, seem to advance further arguments in favour of the idea, suggested by some authors, that most of PSR were formed in binary systems. 相似文献
3.
The results obtained from our IUE observations of some Scuti stars and in particular 71 Tau and 69 Tau are reviewed. 71 Tau is the second brightest X-ray source of the Hyades cluster; on the contrary 69 Tau, very similar to 71 Tau in the optical range, does not show X emissions. The complex and in somewhat controversial scenario obtained from this survey is also discussed. In particular we consider the X-ray emission detected in some Scuti with respect to the chromospheric activity level as measured through the MgII line and to other stellar parameters. 相似文献
4.
M. Fracassini F. Manzolini L. E. Pasinetti M. Ruggenini 《Astrophysics and Space Science》1980,69(2):401-423
Apparent radius, visual brightness, effective temperature and absolute radius for 416 B5 v-F5 v stars of the catalogue of the Geneva Observatory (Rufener, 1976) have been determined.Twenty-eight stars, anomalous in log versus (m
v)0 diagrams, have been singled out. A good correlation for seven stars, in common with the list of Hanbury Brownet al. (1974), has been found. Similar parameters determined for 279 B5 v-F5 v stars of two preceding papers (Fracassiniet al., 1973, 1975) have allowed us to determine the averaged diagrams logq
v/q, logR/R
and logT
e versus (B-V)0 for 695 B5 v-F5 v stars.Moreover, in the present paper a good correlation logq
v/q versus logR/R
and careful relation M
v=–7.40logR/R
+3.31 for B5 v-F5 v stars have been determined. Plain correlations between logR/R
and blanketing parameterm
2 for some spectral types seem to point out that there arereal differences in the absolute radii of stars of thesame spectral type, in agreement with recent researches on the HR diagram (Houck and Fesen, 1978).Systematic differences between double (spectroscopic and visual) and single stars are found. In particular, the averaged relation m
2 versus logR/R
shows that A2 v-F5 v double stars may have a higher metallicity indexm
2 and smaller absolute radii than single stars. Finally, the diagram logv sini versus logR/R
confirms some properties of binary systems found by other researchers (Huang, 1966; Plavec, 1970; Levato, 1974; Kitamura and Kondo, 1978).Thesis for the degree in Applied Physics. 相似文献
5.
M. Fracassini L. E. Pasinetti F. Castelli E. Antonello L. Pastori 《Astrophysics and Space Science》1983,97(2):323-335
The peculiar δ Del-variable ? Puppis (F6IIp) has been analysed on nine UV high-resolution spectra in the region of Mgii h- and k-lines. This analysis has shown: (1) The Mgii emission is present during the whole pulsation period and increases with increasing luminosity. Maximum emission fluxes seem to occur at phases 0.96–0.12. (2) The phase shift between intensity maxima of Caii and Mgii chromospheric emissions is probably about 0.26. Moreover, it seems that the phase shift between ? Pup and the Cepheid β Dor is longer for the Mgii emission (~0.44) than for the Caii one (~0.27). (3) Violet-red asymmetries are present in emission components. Moreover, the violet component K1V has always an intensity higher than the red one K1R. (4) The averaged radial velocity (RV) curve obtained from three metallic lines is in agreement with that obtained in the optical region. The RV curves of red emission and absorption components are rather similar to that of the metallic lines. Near the minimum of this RV curve, the chromospheric emissions show an intensity enhancement with a negative phase shift similar to that of light curve (~?30 deg). (5) A model with an emitting extended atmosphere around the star is proposed to explain an emission like feature in the self-reversed absorption component K3 and in K1. 相似文献
6.
Livio Pastori Elio Antonello Massimo Fracassini Laura E. Pasinetti 《Astrophysics and Space Science》1982,86(1):179-184
The results of radial velocity measures of the star o And from high dispersion plates relative to the years 1964, 1966, 1975 and 1976 are given. The averaged values of the 1964 and 1966 plates confirm the existence of the minimum in the trend of the radial velocities and fit well the curve obtained in the hypothesis of periodic long-term radial velocity variations with the period of 23.5 years (Fracassiniet al., 1977). Preliminary orbital elements in the hypothesis of a long period spectroscopic binary system have been tentatively drawn. 相似文献
7.
8.
Massimo Fracassini Laura E. Pasinetti Giancarlo Pelagatti 《Astrophysics and Space Science》1975,35(2):313-320
Preceding research on 172 B5V-A5V stars (Fracassiniet al., 1973) has been extended to cover 116 A5V-F5V stars of the catalogue of Geneva Observatory (Rufener, 1971), to test the validity of the method for later type stars. Figure 2 shows a satisfactory agreement between our results and those obtained by Gaposchkin (1958) using data from 82 eclipsing binary systems. Furthermore, our results also seem to confirm that the Sun has an absolute radius larger than that averaged from F5V-G0V stars. There is also a good agreement with the apparent radii of α Aql and α C Mi determined by Hanbury Brownet al. (1967, 1974). Three other stars, which are anomalous in the log α″ vsm vdiagram have been added to those selected in the preceding paper. No systematic differences among the absolute radii of stars of the same spectral type, in the Hyades, Pleiades and Praesepe, have been found. 相似文献
9.
10.
An empirical relation which relates the 408 MHz galactic continuum background temperature (408GCBT) to dispersion measures, position and radio-luminosity of 325 pulsars is obtained by means of multple stepwise regression analysis. This relation showns that pulsars may be considered as galactic probes for the distribution of 408GCBT and interstellar electron density (IED) in interstellar medium (ISM).Peculiar pulsars (O-C±2.5) point out galactic regions where the observedT
408 are higher (or lower) andn
e
lower (or higher) than the averaged ones.Normal pulsars (–2.5T
408 andn
e
are in agreement, on, the average.Standard pulsars (O-C±0.05) show galactic regions where observed and computedT
408 andn
e
are in good agreement. Recent models of pulsar disk systems, suggested by Michel and Dessler (1981) could justify the conclusions drawn for peculiar pulsars having O-C>2.5. 相似文献