What does it mean the number after the stellar class? Magnitude?

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Discussion Overview

The discussion centers on the meaning of the number and letters following the stellar class designation, specifically in the context of stellar classification systems. Participants explore the implications of these designations, including subclass and luminosity class, as well as their relevance to the characteristics of stars.

Discussion Character

  • Technical explanation, Conceptual clarification

Main Points Raised

  • One participant notes that the number after the stellar class, such as in G2 for the Sun, indicates a subclass, suggesting that lower digits correspond to cooler stars.
  • Another participant explains that the Roman numeral following the spectral class represents the luminosity class, providing a detailed list of classifications from hyper giants to white dwarfs, and confirms that the Sun is classified as a G2 V star.
  • Subclasses of the luminosity class are mentioned, with labels such as a, ab, and b, indicating further distinctions within the main categories.

Areas of Agreement / Disagreement

Participants generally agree on the definitions and classifications related to stellar classes and luminosity, but the discussion does not delve into any disagreements or alternative interpretations.

Contextual Notes

None noted.

Who May Find This Useful

Individuals interested in astrophysics, stellar classification, or astronomy may find this discussion relevant.

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What does it mean the number after the stellar class? Magnitude?
 
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Like in G2 for Sun? Subclass. The lower the digit, the colder the star.
 
If instead, you mean the roman numeral sometimes placed after the spectral class, this is the luminosity class as follows:

0 Hyper giant
I Super giant
II Bright giant
III Normal giant
IV Sub giant
V Main sequence (dwarf)
VI Sub dwarf
VII White dwarf

Thus the Sun is a G2 V star.

Sub classes of the luminosity class are labled a,ab & b
 
Great.
 

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