Recent observations of the rotation curve of M31 show a rise of the outer part that cannot be understood in terms of standard dark matter models or perturbations of the galactic disk by M31?s satellites. Here, we propose an explanation of this dynamical feature based on the in?uence of the magnetic ?eld within the thin disk. We have considered standard mass models for the luminous mass distribution, a Navarro?Frenk?White model to describe the dark halo, and we have added up the contribution to the rotation curve of a magnetic ?eld in the disk, which is described by an axisymmetric pattern. Our conclusion is that a signi?cant improvement of the ?t in the outer part is obtained when magnetic effects are considered. The best-?t solution requires an amplitude of ?4 ?G with a weak radial dependence between 10 and 38 kpc.
Advertised on
References
(2010) The Astrophysical Journal Letters, Volume 723, Issue 1, pp. L44-L48
It may interest you
-
The Necklace nebula is a bipolar, post-common-envelope planetary nebula, the central star of which has been shown to have a dwarf carbon star companion. We aim to understand the origins of the Necklace and its dwarf carbon central star. We study the carbon abundance of the nebula through far-ultraviolet spectroscopy obtained with the Hubble Space Telescope. Furthermore, through simultaneous modelling of multi-band light and velocity curves, we attempt to constrain the parameters of the central star system. Puzzlingly, we find that the region of the inner nebula observed with the Hubble SpaceAdvertised on -
The most massive stars in the universe are often born and evolve in binary and multiple systems — that is, in pairs or groups bound by their mutual gravity. Understanding how they interact with each other is key to explaining everything from their formation to the impact they have on the galaxies they inhabit. The MONOS project (Multiplicity Of Northern O-type Spectroscopic systems) aims to study these systems in the northern sky, combining spectroscopic observations (which analyze light split into its component colors to measure stellar velocities and physical properties) with photometryAdvertised on -
Research on the formation, origin, and evolution of the dichotomy between the thin and thick disk components of the Milky Way has been a major topic of study, as it is key to understanding how our Galaxy formed. However, this is not an easy task, since populations defined by their morphology or kinematics show a mixture of chemically distinct stellar populations. Age therefore becomes a fundamental parameter for understanding the evolution of the Galactic disk. Our goal is to derive the age and metallicity distributions of the thin and thick disks defined kinematically, in order to revealAdvertised on