How Can We Measure Redshift Using the Spectrum of a Star?

Click For Summary

Discussion Overview

The discussion revolves around the measurement of redshift using the spectrum of a star, focusing on the identification of elements through absorption lines and the implications of spectral patterns for determining redshift or blueshift. The scope includes conceptual understanding and technical reasoning related to spectroscopy in astrophysics.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant questions whether the observed position of absorption lines could indicate the presence of different elements rather than redshift or blueshift.
  • Another participant suggests that the relative strengths and spacing of spectral features can help identify elements and determine redshift by matching patterns with known stars.
  • A participant acknowledges that analyzing the entire spectral pattern is crucial for determining redshift, noting that relying on a single absorption line would complicate this determination.
  • It is mentioned that intensity distribution in the spectrum can provide additional clues, even in the absence of clear lines, and that having more spectral detail aids in confirming the identification of redshift or blueshift.

Areas of Agreement / Disagreement

Participants express differing views on the reliability of identifying elements based solely on absorption lines, with some emphasizing the importance of the entire spectral pattern while others raise concerns about potential misidentification. The discussion remains unresolved regarding the implications of these observations for redshift measurement.

Contextual Notes

There are limitations regarding assumptions about the uniqueness of spectral lines for specific elements and the potential for misinterpretation when only a single line is available. The discussion does not resolve these uncertainties.

Phys12
Messages
351
Reaction score
42
As far as I know, when we use the spectrum of a star, we see where the absorption lines are and using this, we can detect the elements that are present in the star. We also measure whether those absorption lines are supposed to be for a particular element. But why is it not possible that the star contains a different element altogether because the absorption lines are in a different place instead of the spectrum being redshifted/blueshifted?

Thanks!
 
Astronomy news on Phys.org
The relative strengths and the relative spacing of spectral features provide a lot of information which can be used to help identify them. You can match the patterns with other known stars to work out the redshift.
 
Jonathan Scott said:
The relative strengths and the relative spacing of spectral features provide a lot of information which can be used to help identify them. You can match the patterns with other known stars to work out the redshift.
Oh, so it's because we look at the entire pattern, got it. So, if it were the case, that we looked at just one absorption line (because that's all that we'd have), then we couldn't determine the redshift/blueshift, right?
 
Phys12 said:
Oh, so it's because we look at the entire pattern, got it. So, if it were the case, that we looked at just one absorption line (because that's all that we'd have), then we couldn't determine the redshift/blueshift, right?
We also have clues from the intensity distribution of the spectrum even where there are no clear lines, and if there was only one line it might well be the strongest expected one for that type of object, but certainly the more detail the easier it is to be sure.
 
  • Like
Likes   Reactions: Phys12

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 11 ·
Replies
11
Views
5K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 26 ·
Replies
26
Views
6K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K