Publications by James Binney
Accretion by galaxies
ASTR SOC P 197 (2000) 107-114
Both theory and observation indicate that galaxies like the Milky Way accrete matter at the rate of a few M. per year.
A dynamical model of the inner galaxy
Monthly Notices of the Royal Astronomical Society 314 (2000) 433-452
An extension of Schwarzschild's galaxy-building technique is presented that enables one to build Schwarzschild models with known distribution functions (DFs). The new extension makes it possible to combine a DF that depends only on classical integrals with orbits that respect non-classical integrals. With such a combination, Schwarzschild's orbits are used only to represent the difference between the true galaxy DF and an approximating classical DF. The new method is used to construct a dynamical model of the inner Galaxy. The model is based on an orbit library that contains 22 168 regular orbits. The model aims to reproduce the three-dimensional mass density of Binney, Gerhard & Spergel, which was obtained through deprojection of the COBE surface photometry, and to reproduce the observed kinematics in three windows - namely Baade's Window with (l, b) = (10, -40) and two off-axis fields at (80, 70) and (120, 30). The viewing angle is assumed to be 200 the long axis of the bar and the pattern speed is taken to be 60km s-1 kpc-1. The model fits essentially all the available data within the innermost 3 kpc. The axial ratio and the morphology of the projected density contours of the COBE bar are recovered to excellent accuracy within corotation. The kinematic quantities - the line-of-sight streaming velocity and velocity dispersion, as well as the proper motions when available - are recovered, not merely for the fitted fields at (10, -40) and (80, 70), but also for three new fields at (80.4, -60), (10.21, -10.67) and (-10.14, 10.81). The dynamical model deviates most from the input density close to the Galactic plane just outside corotation, where the deprojection of the surface photometry is suspect. The dynamical model does not reproduce the kinematics at the most distant window, (120, 30), where disc contamination of the data may be severe. Maps of microlensing optical depth are presented both for randomly chosen stars and for stars that belong to individual components within the model. While the optical depth to a randomly chosen star in Baade's Window is half what measurements imply, the optical depth to stars in a particular component can be as high as the measured values. The contributions to the optical depth towards randomly chosen stars from lenses in different components are also given.
Dynamics of the solar neighborhood
ASTR SOC P 182 (1999) 285-296
The Hipparcos mission has prompted a thorough reanalysis of the kinematics of the Solar neighborhood. Reliable proper motions are now available for a photometrically complete sample of similar to 10(6) stars, but the largest complete sample of stars with good parallaxes contains only similar to 10(4) stars. The latter sample yields precise values for the first and second moments of near main-sequence stars as a function of color. The effects of the secular increase in velocity dispersion are very evident. From these moments one can redetermine the velocity of the LSR and the age of the Solar neighborhood rather precisely. One can also determine how the density of stars in velocity space varies in the neighborhood of the LSR. This density distribution proves to be significantly more complex than the Schwarzschild distribution and may be affected by the Galactic bar. The larger sample for which only proper motions can be obtained allows one to probe gradients in the large-scale streaming motions that the Oort constants aim to describe. Here again the data imply a significantly more complex situation than has been considered previously. It is probable that these complexities are in part caused by spiral arms and/or the central Galactic bar.
The persistence of warps in massive halos
GALACTIC HALOS: A UC SANTA CRUZ WORKSHOP 136 (1998) 379-381
The persistence of warps in spiral galaxies with massive haloes
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 297 (1998) 1237-1244
The LMC microlensing events: Evidence for a warped and flaring Milky Way disk?
ASTROPHYSICAL JOURNAL 501 (1998) L45-L49
Galactic astronomy
Princeton Univ Pr, 1998
GALACTIC ASTRONOMY introduces all astronomical concepts necessary to understand the properties of galaxies, including coordinate systems, magnitudes and colors, ...
The outer rotation curve of the Milky Way
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 287 (1997) L5-L7
The microlensing optical depth of the COBE bulge
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 289 (1997) 651-659
Summary of the RAS Discussion Meeting on HIPPARCOS and the H-R Diagram
OBSERVATORY 117 (1997) 201-204
The photometric structure of the inner Galaxy
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 288 (1997) 365-374
The kinematics of main-sequence stars from Hipparcos data
ESA SP PUBL 402 (1997) 473-477
We analyze a kinematically unbiased sample of 5610 stars around the south celestial pole that (i) have MK spectral types in the Michigan catalogues with luminosity class V and (ii) had photometric parallaxes that placed them within 80 pc of the Sun. We bin the stars by B - V and determine for each bin the solar motion from proper motions alone. As expected, the U and W components of the derived solar motions do not vary significantly from bin to bin, while the V component varies systematically. As the classic Stromberg relation predicts, V is a linear function of the variance S-2 within each bin around the solar motion. Extrapolating V (S-2) to S = 0 we determine the solar motion with respect to the LSR, obtaining a significantly smaller value of V than is usually employed. Parenago's discontinuity in the dependence of S-2 on spectral type emerges with exceptional clarity.
