Strömgren Sphere Fitter

Joachim Köppen Kiel May 2016

This script computes the properties of photoionized nebulae and their central stars, given the observational data and supplementary assumptions shown in the light green input fields. Hit the Enter key or the compute button to recompute with the new values.

One of the four parameters at the top: observed line flux, angular diameter, electron density, and distance can be selected as being computed from the others. Click on the small button to the right to select a parameter, which is indicated by a light blue background of its field.

For example, if one wants to determine the distance to a nebula, select the distance as output, fill in all the data of the green fields, and hit the Enter key... This also gives tha mass and the radius of the nebula. A guess of the stellar temperature gives its luminosity, and if you enter the expansion velocity, you'll get its expansion age.

Angular diameter [arcsec]
Electron density [1/cm³]
Distance [kpc]

Extinction c(Hβ)
Electron temperature [K]
Volume filling factor

Ionizing photons/sec
Stellar temperature [K]
Stellar luminosity [Lsun]
Stellar radius [Rsun]

Mass [Msun]
Radius [pc]
Expansion velocity [km/s]
Expansion age [Myr]

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