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This observation clearly contradicts multiple other measurements of the MW mass which is not really explained. Given quite a complex set of assumptions that wen
by sega_sai 3y ago
This observation clearly contradicts multiple other measurements of the MW mass which is not really explained. Given quite a complex set of assumptions that went into this particular derivation, I am personally quite sceptical about this measurement, but no one have identified a specific flaw of the study.
- AnimalMuppet 3y agoIf I understood this correctly, this mass was derived from the rotation curve, which was itself derived from the motions of stars. The other mass estimate was from (a rotation curve derived from?) neutral gas. So there's maybe some room for the relationship between the motion of the stars and the motion of the neutral gas to be not what we expect. Or, there's room for there to be a flaw in this study. Or for a flaw in the studies (I assume plural) that used neutral gas, but it would have to be a flaw in the assumptions, or in the techniques common to all of the studies.
- sega_sai 3y agoMost of mass estimates of the MW in the outskirts come from measuring motions of stars (just not in the disk of the MW) dwarf galaxies, globular clusters or stellar streams. These measurements have their own issues, but now many of these measurements broadly agree and this new one very is an outlier. Measurements using gas have their own issues, and also they do not go as far away from the galactic centre as the new rotation curve from the paper.