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The Dark Massive Halo in the Elliptical Galaxy NGC 5266

Published online by Cambridge University Press:  07 August 2017

A. Pizzella
Affiliation:
Istituto Astronomico, Roma, Italy
R. Morganti
Affiliation:
ATNF, Australia & Istituto di Radioastronomia, Bologna, Italy
M.E. Sadler
Affiliation:
School of Physics, University of Sydney, Australia
F. Bertola
Affiliation:
Dipartimento di Astronomia, Padova, Italy

Extract

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Recent observations with the Australia Telescope reveal that the elliptical galaxy NGC 5266 has a disk like structure of neutral hydrogen extending as far as almost 10 Re which approximatively lies along the galaxy's major axis, at 65° apart from the inner minor–axis dust lane (Varnas et al 1987). From the present data is not clear whether the HI structure and the dust lane are two distinct disks or a single warped structure. The regularity of the velocity field of the HI structure allow us to use it as a probe of the potential of NGC 5266. The velocity curve along the major axis is flat till the last measured point (rmax ~ 10′) at Vrot = 200km/s. Assuming that the gas in moving in circular orbits, we can derive the mass of the galaxy inside to this radius. The mass–to–light ratio M/LB rises from about 3 in the central regions to 12 at 9 Re (D = 57.6 Mpc), thus indicating that NGC 5266 is embedded in a dark massive halo. Moreover the representative point (cumulative M/LB within the last measured point) of NGC 5266 in the diagram log(M/LB) – log(Re) falls well within the region characteristic of spiral galaxies (Figure 2, Bertola et al. 1993), as do ellipticals previously studied in HI, thus reinforcing the suggestion (Bertola et al. 1993) of a parallel behaviour of the dark matter in elliptical and spiral galaxies.

Type
Poster Papers
Copyright
Copyright © Kluwer 1995 

References

Bertola, F., Pizzella, A., Persic, M., Salucci, P., 1993, ApJ Letters 416, L45.CrossRefGoogle Scholar
Varnas, S. R., Bertola, F., Galetta, G., Freeman, K. C., Carter, D., 1987, ApJ 313, 69.CrossRefGoogle Scholar