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Observations of the dynamics of eight early-type galaxies
Measurements of the velocity dispersion profiles and rotation curves ofone lenticular and seven elliptical galaxies are presented. Long-slitspectra along the major axes of the eight early-type galaxies covering arange of ellipticities were obtained in the range 5000 to 6000 A, andcalibrated for small-scale sensitivity variations, sky brightness andwavelength and intensity; velocities and velocity dispersions weremeasured using direct and Fourier techniques. Estimates of the velocitydispersion and rotation velocities made by the two methods are shown tobe in good agreement, and the low rotation velocities found by otherauthors are confirmed. All the galaxies are observed to exhibitdecreasing or constant values of the velocity dispersion with increasingradius. Examination of the velocity dispersion profiles of the galaxiesreveals those galaxies with dispersion profiles falling more steeplythan predicted by isotropic models to be dominated by radial motions atlarge radii, and those with flat dispersion profiles to be easilyinterpreted in terms of increasing mass-to-light ratio with radius.Detailed descriptions of the dynamical properties of individual galaxiesare also presented.
| Spectroscopic observations of three elliptical galaxies
Spectroscopic observations of NGC 4472, NGC 5813, and IC 4296 arereported. Rotation curves, velocity dispersion profiles, and linestrength profiles were obtained by a Fourier quotient method and a crosscorrelation method. NGC 4472 and NGC 5813 are found to rotate slowly,which provides additional support for the hypothesis that the shapes ofelliptical galaxies are due to velocity anisotropies rather than torotation. IC 4296 rotates quite rapidly, which is consistent withisotropic oblate models.
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Osservazione e dati astrometrici
| Costellazione: | Idra |
| Ascensione retta: | 09h16m42.85s |
| Declinazione: | -06°42'56.8" |
| Magnitudine apparente: | 8.369 |
| Distanza: | 952.381 parsec |
| Moto proprio RA: | -15.6 |
| Moto proprio Dec: | -26.7 |
| B-T magnitude: | 9.994 |
| V-T magnitude: | 8.504 |
Cataloghi e designazioni:
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