Can two stars have the same apparent but different absolute magnitudes

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Discussion Overview

The discussion centers on the relationship between apparent and absolute magnitudes of stars, exploring whether two stars can have the same apparent magnitudes but different absolute magnitudes, and vice versa. The scope includes conceptual clarifications and technical explanations related to stellar luminosity and distance effects.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants assert that two stars can have the same apparent magnitudes but different absolute magnitudes due to their varying distances from Earth.
  • Others explain that a bright star far away can appear fainter than a less bright star that is closer, illustrating the dependence of apparent magnitude on distance.
  • It is noted that for two stars with the same absolute magnitude, one must be farther away than the other to have different apparent magnitudes.
  • One participant mentions that extinction affects apparent magnitude, making a star appear dimmer due to absorption or scattering of light.
  • There are inquiries about the absolute intensity scale and its reference point, with some participants stating that absolute magnitude is defined as the apparent magnitude a star would have at a distance of 10 parsecs.

Areas of Agreement / Disagreement

Participants generally agree on the definitions and relationships between apparent and absolute magnitudes, but there are multiple inquiries and clarifications regarding the absolute intensity scale, indicating some uncertainty in that area.

Contextual Notes

Some participants express confusion regarding the absolute intensity scale and its baseline reference point, which remains unresolved in the discussion.

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Can two stars have the same apparent magnitudes but different absolute magnitudes?

what about if two stars have the same absolute magnitudes but different apparent magnitudes?
 
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Yes to both. Absolute magnitude is independent of distance (how far the star is from us), while apparent magnitude does depend on distance. A bright star very far from us will appear fainter than a less bright star very close to us.

For two stars with different absolute magnitudes to have the same apparent magnitude, the fainter star could be nearer to us and the brighter star could be farther from us.

For two stars with the same absolutely magnitude but different apparent magnitude, one star could be farther than the other.

Extinction (the absorption or scattering of light) also affects apparent magnitude by making a star appear dimmer.
 
Yes the two can have same absolute intensity and different relative magnitudes and vice versa.

As the light travels it spreads, and hence the intensity of light reaching the Earth lessens.
For a star near to us this spreading would be less and for a distant one would be more.So the star far away would seem to be fainter even if it has the same absolute intensity.
 
Apparent magnitude is the luminosity of any given star viewed from earth. Absolute magnitude is the comparative luminosity of stars viewed from the same distance.
 
Question

Could you please elaborate on the absolute intensity scale.
What is chosen as its base line or reference point??
 
anonymoussome said:
Could you please elaborate on the absolute intensity scale.
What is chosen as its base line or reference point??

Absolute magnitude is the visual magnitude the star would have at a distance of 10 parsecs(32.616 lightyears)
 
anonymoussome said:
Could you please elaborate on the absolute intensity scale.
What is chosen as its base line or reference point??

The absolute magnitude of a star is the apparent magnitude that the star would have if it were at a distance of 10 parsecs from the Earth, i.e., for stars at 10 parsecs,

absolute magnitude = apparaent magnitude.

[edit]Somehow (went some time without refreshing), I missed the reply by Janus[/edit]
 

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