The Orion Nebula on Starry Night

[joshig1983]

The directions are easy enough to find from Hubble photos(where in the photos they appear) but how are they getting the distances? Can they really get the distances down to a few AU or do they just know the disks are in M42 and just artistically pick a distance for the 3D model?

[Neueregel]

@joshig1983 You can know a star's distance from either from Parallax (in arcseconds) and proper motion or though Sprectral Analysis and then construct a 3D model.

[IARRCSim]

@Neueregel Do you think they used absorption of light from the nebula's gas to determine where it was in the nebula? Maybe the different amounts of light filtering could place different stars at fairly reliable depths into the nebula. The estimation of the nebula's distance has a 40ly confidence interval so it is unlikely that the stars are plotted by distance estimations relative to our position.

[Neueregel]

@IARRCSim Of course. Orion Nebula is a diffuse and reflection nebula which means it creates light emissions that we detect through it's Spectrum which is slightly polarized. Most stars in that nebula are probably young, hot and blue stars because the dense interstellar clouds and dust inside the nebula assists stellar formation like it happens in globular clusters. The confidence interval for Orion nebula is estimated through it's receding velocity (derived from it's Redshift)