Redshift data on stars the same distance from earth

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Discussion Overview

The discussion centers on the inquiry regarding the existence of detectable redshift differences in stars that are equidistant from Earth but located in various directions. This topic relates to the broader question of whether the universe exhibits a preferred direction of expansion, and participants seek hard research data to support or refute this idea.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant requests hard research data demonstrating that there is no detectable redshift difference in stars at the same distance from Earth, suggesting a link to the universe's expansion direction.
  • Another participant notes that individual stars are typically bound within galaxies and do not exhibit expansion, indicating that redshift in nearby galaxies is primarily influenced by local motions rather than cosmological effects.
  • A suggestion is made to consult the SIMBAD database for hard data on galactic redshifts, with an emphasis on measuring averages for entire galaxies rather than individual stars.
  • Links to additional resources are provided to assist in finding relevant data on redshift measurements.

Areas of Agreement / Disagreement

Participants express differing views on the nature of redshift in stars and galaxies, with some emphasizing local motions and others seeking data to clarify the relationship between redshift and cosmic expansion. The discussion remains unresolved regarding the specific question posed about detectable redshift differences.

Contextual Notes

The discussion highlights limitations in available data and the challenges of measuring redshift in individual stars versus galaxies, as well as the dependence on definitions of redshift in different contexts.

Jim Hasty
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Can anyone in the cosmology community direct me to hard research data that specifically demonstrates: there is no detectable redshift difference in stars that are the same distance from the Earth but in all different directions. This is of course related to 'does the universe have a preferred direction of expansion', the literature of which I find on google does not provide data, just brief conclusions. Thanks.
 
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Individual stars tend to be visible within our galaxy but there is no expansion of such bound objects. Nearby galaxies have the majority of their red- or blue-shift determined by local motions. It's only when you get to more distant galaxies that cosmological redshift starts to dominate, and by then you cannot make out individual stars. Again their motion would be principally that within the galaxy, what you need to do is measure the average for the whole galaxy.

For hard data on galactic redshifts, I would suggest you start with the SIMBAD database but there are others. Once you know what details you want, you can get more specific advice on search criteria.
 
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GeorgeDishman said:
Individual stars tend to be visible within our galaxy but there is no expansion of such bound objects. Nearby galaxies have the majority of their red- or blue-shift determined by local motions. It's only when you get to more distant galaxies that cosmological redshift starts to dominate, and by then you cannot make out individual stars. Again their motion would be principally that within the galaxy, what you need to do is measure the average for the whole galaxy.

For hard data on galactic redshifts, I would suggest you start with the SIMBAD database but there are others. Once you know what details you want, you can get more specific advice on search criteria.
Thank you so much, George. This is incredible and helpful.
 

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