A Galactic Bar to Beyond the Solar Circle and its Relevance for Microlensing
نویسنده
چکیده
The Galactic kinematics of Mira variables have been studied using infrared photometry, radial velocities, and Hipparcos parallaxes and proper motions. For Miras in the period range 145 to 200 days (probably corresponding to [Fe/H] in the range –0.8 to –1.3) the major axes of the stellar orbits are concentrated in the first quadrant of Galactic longitude. This is interpreted as a continuation of the bar-like structure of the Galactic Bulge out to the solar circle and beyond.
منابع مشابه
The effect of variation of stellar dispersion velocities by the galactic latitude in interpreting gravitational microlensing observations
Our galaxy is a spiral galaxy and its stars are mostly in a thin disk and rotate around the galactic center. The vertical component of the dispersion velocity of stars is a function of the galactic latitude and decreases with increasing it. In the galactic Besancon model, this dependence is ignored and they just consider the dependence of dispersion velocity on the stellar age. Becanson model i...
متن کامل3D self-consistent N-body barred models of the Milky Way I. Stellar dynamics
Many 3DN -body barred models of the Galaxy extending beyond the Solar circle are realised by selfconsistent evolution of various bar unstable axisymmetric models. The COBE/DIRBE K-band map, corrected for extinction, is used to constrain the location of the observer in these models, assuming a constant mass-to-light ratio. The resulting view points in the best matching models suggest that the in...
متن کاملCuspy Dark - Matter Halos and the Galaxy
The microlensing optical depth to Baade's Window constrains the minimum total mass in baryonic matter within the Solar circle to be greater than ∼ 3.9×10 10 M ⊙ , assuming the inner Galaxy is barred with viewing angle ∼ 20 •. From the kinematics of solar neighbourhood stars, the local surface density of dark matter is ∼ 30 ± 15 M ⊙ pc −2. We construct cuspy haloes normalised to the local dark m...
متن کاملThe Galactic Kinematics of Mira Variables
The galactic kinematics of Mira variables derived from radial velocities, Hipparcos proper motions and an infrared period-luminosity relation are reviewed. Local Miras in the 145-200day period range show a large asymmetric drift and a high net outward motion in the Galaxy. Interpretations of this phenomenon are considered and (following Feast and Whitelock 2000) it is suggested that they are ou...
متن کاملAre the Ogle Microlenses in the Galactic Bar?
The analysis of the first two years of OGLE data revealed 9 microlensing events of the galactic bulge stars, with the characteristic time scales in the range 8.6 < t0 < 62 days, where t0 = RE/V . The optical depth to microlensing is larger than (3.3 ± 1.2) × 10, in excess of current theoretical estimates, indicating a much higher efficiency for microlensing by either bulge or disk lenses. We ar...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2000