Deborah & William Hillyard
Deborah & William Hillyard
Deborah & William Hillyard
Deborah & William Hillyard
Deborah & William Hillyard
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Science - Stars - Stellar Classes
Stellar Classes
Stars are divided up into a series of classes, as shown in the menu on the left, known as the Morgan-Keenan system. This classification is based on their spectral characteristics; essentially indicating the temperature of the chromosphere. There are further subdivisions within each class, indicated by a number from 0 to 9 so that G2 star, like our sun for example, is two-tenths of the way between G0 and K0.
An additional element is the luminosity which gives a reasonable indication of a star's size. This is shown by the numerals 0 through VII as shown in the table to the right. The Sun is a luminosity V star, so its full classification is type G2V. In fact, the luminosity scale is further subdivided, and you can find the complete luminosity scale here.
Just click on any "Type" in the menu to see more information about stars of that type as well as some examples.
An additional element is the luminosity which gives a reasonable indication of a star's size. This is shown by the numerals 0 through VII as shown in the table to the right. The Sun is a luminosity V star, so its full classification is type G2V. In fact, the luminosity scale is further subdivided, and you can find the complete luminosity scale here.
Just click on any "Type" in the menu to see more information about stars of that type as well as some examples.
| Class (Click for More Info) |
General Color | Surface Temperature |
| Type O | Blue | Over 25,000º K |
| Type B | Blue/ White |
Between 11,000º & 25,000º K |
| Type A | White | Between 7,500º & 11,000º K |
| Type F | Yellow/ White | Between 6,000º & 7,500º K |
| Type G | Yellow | Between 5,000º & 6,000º K |
| Type K | Orange | Between 3,500º & 5,000º K |
| Type M | Red | Between 2,000º & 3,500º K |
| Type WR | Blue | 25,000º K to over 50,000º |
| Types L,T & Y | Brown/ Magenta | Below 2,000º K |
| Others | Various | Various |
Select:
The image to the right shows a comparison of stars from each class that are on the main sequence. Click to enlarge.
| Type | Description |
| 0 | Hyper-giant |
| I | luminous supergiants |
| II | Luminous giants |
| III | Giants |
| IV | Sub-Giants |
| V | Main Sequence/Dwarf Stars |
| VI | Sub-Dwarf |
| VII | White Dwarf |
