I Redshift Along Galactic Plane: Study & Research

[Ennio]

How do the redshift change along the galactic plane or ortoganal to the galactic plane? If we measure a redshift of a star on the backgorund of other side of our galactic plane (where most stars are concentrated) are the redshifts avaraged higher? Is there a study or research discussing this topic? Thank you

 

[mfb]

Within our galaxy red- and blueshift just comes from the overall rotation of the galaxy plus a bit of random motion. What exactly you measure depends on where you look plus a bit of random chance. There is no redshift from the expansion of the universe as that doesn't have an effect within our galaxy.

of other side of our galactic plane (where most stars are concentrated)

Huh?

 

[Ennio]

Within our galaxy red- and blueshift just comes from the overall rotation of the galaxy plus a bit of random motion. What exactly you measure depends on where you look plus a bit of random chance. There is no redshift from the expansion of the universe as that doesn't have an effect within our galaxy.Huh?

"There is no redshift from the expansion of the universe as that doesn't have an effect within our Galaxy"
But we measure the cosmological redshift from Earth and the light, coming from the Background stars, goes through the milky way.. Do we measure higher redshifts along the galactic plane or not? You mean the distribution of the redshifts is the the same all over the sky..

 

[davenn]

But we measure the cosmological redshift from Earth and the light, coming from the Background stars, goes through the milky way.. Do we measure higher redshifts along the galactic plane or not? You mean the distribution of the redshifts is the the same all over the sky..

again HUH!

what background stars. We can only see around 1/3 to 1/2 of the stars in our galaxy (the Milky Way) ... the rest are hidden from us behind the core and other arms.

what background stars ??

There won't be any cosmological red shift seen from stars within our galaxy because they are all gravitationally bound

 

[mfb]

"There is no redshift from the expansion of the universe as that doesn't have an effect within our Galaxy"
But we measure the cosmological redshift from Earth and the light, coming from the Background stars, goes through the milky way.. Do we measure higher redshifts along the galactic plane or not? You mean the distribution of the redshifts is the the same all over the sky..

Are you asking about the integrated Sachs-Wolfe effect? Our galaxy contributes a bit to it, but the contribution is tiny.

 

[stefan r]

Dust causes a reddening effect called extinction. That is not the same as a red shift.

Suppose you build a few huge stoplights out in space. Dust in Milky Way will make the green light dimmer when compared to the red light. That is the same as the Sunset/Sunrise. The Sun's light has not changed but you see more of a part of that light.

If you launch the stoplight away at relativistic speeds the stop light will have a yellow-orange-infrared cycle instead of green-yellow-red. If you approach a stoplight at relativistic speeds you would see a blue-green-orange cycle. The shifts do not effect the intensity of the lights.

The Milky Way has a lot of dust and does cause extinction. Part of the disk is rotating away from us and the other part is rotating toward us. That causes a slight Doppler red-shift. The stars on the opposite side of the galaxy are not visible because they are completely blocked by dust. If they were visible there would be on average no measurable red-shift because they are not moving toward or away from us. The far side has perpendicular motion. Individual stars could be coming or going same as nearby stars.