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October 1, 1989The Astrophysical Journal139 citations

Velocities of stars in remote Galactic satellites and the mass of the Galaxy

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DZDennis ZaritskyEOEdward W. OlszewskiRSR. A. Schommer

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Abstract

We present observations of stars in four distant satellites of our Galaxy, Eridanus, Palomar 14, Leo 1, and Leo II. From these data we derive, using a technique of wavelength calibration which utilizes an etalon, the heliocentric systemic velocities of these systems, -21 +/- 4, 72 +/- 4, 285 +/- 3, and 70 +/- 4 km s^-1^, respectively. The value of the velocity for Leo I is in significant disagreement with previously published values. These systems are added to the remote satellite data base from which we estimate the mass of the Galaxy using a statistical method as well as timing arguments. The mass derived using the statistical techniques is 9. 3^+4. 1^₁. 2_ x 10 Mₛun_ assuming radial satellite orbits, and 12. 5^+8. 4^₃. 2_ x 10¹1^ Mₛun_ assuming isotropic satellite orbits. A lower mass limit, 13 x 10¹1^ Mₛun_, was derived from timing arguments, for an age of the universe of 1. 4 x 10¹0^ yr and for the accepted Galactocentric distance of Leo I, and can change by at most 25% for reasonable changes to the input parameters. These values are valid only if Leo I is gravitationally bound to the Galaxy, and we present arguments which support this assumption. We also use the data to acquire preliminary values of the internal velocity dispersions and mass-to-light ratios in Leo I and II.

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Cite This Study

Zaritsky et al. (1989) studied this question.

synapsesocial.com/papers/69dcc47989c4deb67d359ab7https://doi.org/10.1086/167947
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