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dynamics-of-stellar-systems / dynamite

dynamics, age and metallicity indicators tracing evolution
MIT License
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Distance Conversions #228

Open adriano-poci opened 2 years ago

adriano-poci commented 2 years ago

Currently the internal code converts the distance, given in parameters.in in [Mpc], using a simple geometric angular conversion

conversion_factor = distance*1.0e6_dp*tan(pi_d/(648d3))*parsec_km

Compared to a proper cosmological conversion, the discrepancy is >100pc for z > 0.1

Any solution would necessarily need to either assume a cosmology, or allow for user-specified cosmological parameters. I'm guessing the latter would be preferred, but would entail modifications.

Happy for discussion on the best way forward.

maindlt commented 1 year ago

I came across this article "Distance measures in cosmology" that may help in implementing a proper cosmological conversion.

As a note: the conversion happens in multiple places in the code (VisibleComponent.get_M_stars_tot(), Plotter.orbit_plot(), Decomposition.create_orbital_component_files_giu()), perhaps a system parameter would be in order...

dist_ref.pdf