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The mass and light distribution of the galaxy: a three-component model

Published online by Cambridge University Press:  14 August 2015

J. P. Ostriker  and
J. A. R. Caldwell
J. P. Ostriker
Affiliation:
Princeton University Observatory
J. A. R. Caldwell
Affiliation:
Princeton University Observatory

Abstract

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The galaxy is represented schematically by a three-component model: a disc having the form of a modified exponential distribution, a spheroidal (bulge + nucleus) component and a dark halo component which, following the nomenclature of Einasto, we call the corona. The shapes of these components, chosen on the basis of observations of other galaxies, are consistent with imperfect knowledge of the Galaxy; values of the adjustable parameters are chosen by a least square minimization technique to best fit the most accurate kinematical and dynamical galactic observations. The local radius, circular velocity and escape velocity are found to be (R⊙, V⊙, Vesc) = (9.05 ± 0.33 kpc, 247 ± 13 km/s, 550 ± 24) quite close to the values determined from observations directly. The masses in the three components are (MD, MSp, MC) = (0.78 ± 0.13, 0.81 ± 0.09, 20.3) × 1011 M⊙ for a model with coronal radius of 335 kpc. If the quite uncertain coronal radius is reduced to 100 kpc the model is essentially unchanged except that then MC = 6.65 × 1011 M⊙. The disc and spheroidal components have in either case luminosities (in the visual band of (LD, LSp) = (2.0, 0.2) × 1010 L⊙. The galaxy is a normal giant spiral of type Sb-Sc similar to NGC 4565.

Type
VIII. THE SPHEROIDAL COMPONENT
Information
Symposium - International Astronomical Union , Volume 84: The Large-Scale Characteristics of the Galaxy , 1979 , pp. 441 - 450
Copyright
Copyright © Reidel 1979 

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