摘要:

AbstractThe structure of the centre of the galaxy cluster A 1795 and its surroundings, representing different cluster components, has been investigated in several wavelength ranges. A preferred orientation deviating about 10–20° from the north‐south direction has been found for all cluster components. The orientation of the central cD galaxy is in good agreement with this direction, too. There seem to exist hints for antisegregation in luminosity as well as for colour segrega

ISSN:0004-6337    

DOI:10.1002/asna.2113120302

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractA correlation between the masses of cooling flows in clusters of galaxies and the absolute magnitudes of the central parts of the brightest galaxies of the clusters is detected. This correlation is consistent with star formation in the cooling flows according to an initial mass function of stars truncated at stellar masses corresponding to absolute magnitudes in the most probable cases between +7 and +2.

ISSN:0004-6337    

DOI:10.1002/asna.2113120303

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113120304

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractMedium‐resolution spectrophotometry of 19 Seyfert‐I galaxies withMvbetween ‐20mand ‐24mis presented. Balmer line broad and narrow components are decomposed and relative narrow‐line intensities are compared with a grid of power law photoionization models. Diagrams displaying ratios of strong forbidden lines are devised which allow to read power law indices α and ionization parametersUfor individual objects. On the average, α‐values derived from [O I]/[O III]versus [N II]/[O III]are in good agreement with power‐law slope indices αuxderived from continuum measurements at 1450 Å (U) and 0.7 keV (X). However, for the same parameters, the theoretical [S II]/[O III]values appear to be 40% too large. Based on trends in current photoionization models we suggest that this discrepancy might be removed by including a black‐body component in the ionizing continuum and a high‐density component in the narrow‐line region. Mkn 1044 has been isolated as an unusual object whose strong [S II] λλ4068,4076 feature suggests that its NLR emission is dominated by a high‐d

ISSN:0004-6337    

DOI:10.1002/asna.2113120305

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe main aim of this paper is (i) to examine the available metallicity data of open clusters, (ii) to gather a large set of homogeneous estimations of the characteristics, and (iii) to check whether open cluster metallicities are related to spatial and age distribution of these objects.

ISSN:0004-6337    

DOI:10.1002/asna.2113120306

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractFor 458 stars in the Pleiades field from the catalogue of EICHHORNet al. (1970) proper motions were derived on Tautenburg and CERGA Schmidt telescope plates measured with the automated measuring machine MAMA in Paris. The catalogue positions were considered as first epoch coordinates with an epoch difference of ca. 33 years to our observations. The results show good coincidence of proper motions derived with both Schmidt telescopes within the error bars. Comparison with proper motions determined by VASILEVSKISet al. (1979) displays some significant differences but no systematic effects depending on plate coordinates or magnitudes could be found. An accuracy of 0.3″/100a for one proper motion component was estimated. According to the criterion of common proper motion 34 new cluster members were identifie

ISSN:0004-6337    

DOI:10.1002/asna.2113120307

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe shape of some asteroids may be deduced by other ground based means than rotation light curves or advanced techniques like speckle imaging or radar observations: the analysis of high precision astrometry and lunar occultation light curves. Calculations of the phenomena among the cosmogonically interesting case of a double asteroid configuration, when the objects are in contact with each other, are presented with special emphasis on the involved shadow phenomena.

ISSN:0004-6337    

DOI:10.1002/asna.2113120308

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113120309

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractThe problem of interpretation of lightcurves and pole determination is illustrated by a discussion of all observations of (51) Nemausa from 1887 to 1990. A new concept is the introduction of a fictitious convex body which can in principle be directly determined from the observations. The importance of the first and third harmonics in the lightcurves is demonstrated. Different oppositions are connected by the synodicperiod 7.h78293 and the proposed pole is: 19h45m+ 41° (1950). The rotation is probably retrograde and there are indications of a red spot

ISSN:0004-6337    

DOI:10.1002/asna.2113120310

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113120311

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY