As part of the activities of the German Astrophysical Virtual Observatory we have created relational databases to store the detailed assembly histories both of all the haloes and subhaloes resolved by the simulation, and of all the galaxies that form within these structures for two independent models of the galaxy formation physics.
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This allows easy access to many properties of the galaxies and halos, as well as to the spatial and temporal relations between them. Information is output in table format compatible with standard Virtual Observatory tools. They can then request accounts to run similar queries on the databases for the full simulations.
In a second simulation was completed with the same cosmology, the same output structure and the same number of particles as the Millennium Simulation, but in a 5 times smaller box and thus with times better mass resolution.
Halo data were publicly released in with the submission of the paper describing this Millennium-II Simulationand joint galaxy catalogues for both simulations and also for their smaller, openly accessible versions were released in with the acceptance of the paper Guo et al. The combination of multiple simulations of differing mass resolution with improved treatments of many of the underlying astrophysical processes allows this second generation model to represent observed galaxy populations with high fidelity over a substantially broader range of galaxy mass and redshift than the first generation models.
By the specific cosmological parameters used for the two Millennium Simulations based on an analysis of the first-year data from the WMAP satellite in conjunction with the 2dF Galaxy Redshift Survey were no longer consistent with improved parameter estimates based on more recent data. Guo et al reimplemented the model of Guo et al. The parameters of the model were tuned to fit the same observational data as in Guo et al.
Fall Sky The figure below shows the location of the earth relative to the sun on the first day of fall. At local midnight an observer for instance, you!
The equatorial coordinate system is centered on the earth, so the RA and Dec of the earth have no meaning. The Earth The Revolving Earth and the Changing Sky Since the earth revolves around the sun, at the same time each night, a different RA will be on the meridian at different times of the year.
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For instance at midnight for the following dates, the RA's on the meridian are: The Earth The Rotating Earth and the Changing Sky As the earth rotates on its axis, the stars move through the sky over the course of a night.
Like the sun, planets, and the moon, the stars rise in the east and set in the west due to the earth's rotation. Consider the case illustrated below.
As the earth turns, the observer moves.
The graphic illustrates the location of the observer at 4: On the first day of fall Sep. Six months later on the first day of sping Mar.
Summary Changing Sky The figure below gives an overview of the different parts of the sky you can view different times of the year. All observers people are shown at local midnight, except for the fall where observers are shown at midnight, 4: Movement of the Sky Your general knowledge tells you that objects sun, moon, stars, etc.
Due to the revolution of the earth about the sun, these events happen earlier each successive night. Thus Each night a given object will pass over the meridian 4 minutes earlier. This corresponds to 2 hours earlier each month, or 24 hours in one year.
Objects rise and set earlier each day. At a given time, the RA crossing the meridian increases by 4 min.