Fitting orbits to tidal streams with proper motions
arXiv:0908.2081 · doi:10.1111/j.1745-3933.2009.00744.x
Abstract
The Galaxy's stellar halo seems to be a tangle of disrupted systems that have been tidally stretched out into streams. Each stream approximately delineates an orbit in the Galactic force-field. In the first paper in this series we showed that all six phase-space coordinates of each point on an orbit can be reconstructed from the orbit's path across the sky and measurements of the line-of-sight velocity along the orbit. In this paper we complement this finding by showing that the orbit can also be reconstructed if we know proper motions along the orbit rather than the radial velocities. We also show that accurate proper motions of stream stars would enable distances to be determined to points on the stream that are independent of any assumption about the Galaxy's gravitational potential. Such "Galactic parallaxes" would be as fundamental as conventional trigonometric parallaxes, but measureable to distances ~70 times further.
5 pages, 2 figures, submitted to MNRAS Letters
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Cited by in corpus (22)
- Galactic Searches for Dark Matter
- Globular Cluster Streams as Galactic High-Precision Scales - The Poster Child Palomar 5
- More on the structure of tidal tails
- The mass of our Milky Way
- Stream-orbit misalignment I: The dangers of orbit-fitting
- Stellar Streams and Clouds in the Galactic Halo
- The mechanics of tidal streams
- Stellar Streams as Probes of Dark Halo Mass and Morphology: A Bayesian Reconstruction
- Stellar distances from spectroscopic observations: a new technique
- Stream-orbit misalignment II: A new algorithm to constrain the Galactic potential
- Proper Motions of Stellar Streams Discovered in the Dark Energy Survey
- Kinematics and simulations of the stellar stream in the halo of the Umbrella Galaxy
- Inferring the gravitational potential of the Milky Way with a few precisely measured stars
- Constraining the Milky Way Halo Shape Using Thin Streams
- Probabilistic model for constraining the Galactic potential using tidal streams
- Another Look at the EBS: A Stellar Debris Stream and a Possible Progenitor
- Dynamics for Galactic Archaeology
- A statistical method for measuring the Galactic potential and testing gravity with cold tidal streams
- At a Crossroads: Stellar Streams in the South Galactic Cap
- Charting Galactic Accelerations with Stellar Streams and Machine Learning
- Characterization and dynamics of the peculiar stream Jhelum, A tentative role for the Sagittarius dwarf galaxy
- An application of Galactic parallax: the distance to the tidal stream GD-1