Abstract
We derive a virial theorem and an analog for King's formula in modified Newtonian dynamics (MOND; Milgrom 1983) and use these to estimate the mass-to-light ratios (M/Ls) in MOND of the dwarf spheroidal galaxies in the Local Group. We find that the low-velocity dispersion observed in the Fornax dwarf galaxy implies low values for its M/L in MOND: 0.3-1. In particular the derived value in the core of Fornax (0.3) is much lower than expected for a normal old stellar population. Conversely, the velocity-dispersion measurements in Draco and Ursa Minor appear to still require dark matter in MOND. We show that M/L must vary between the dwarf spheroidals around the Galaxy by a factor of order at least 20, even in MOND.
Original language | English (US) |
---|---|
Pages (from-to) | 38-43 |
Number of pages | 6 |
Journal | Astrophysical Journal |
Volume | 397 |
Issue number | 1 |
DOIs | |
State | Published - 1992 |
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
Keywords
- Dark matter
- Galaxies: elliptical and lenticular, cD
- Galaxies: kinematics and dynamics
- Gravitation