The spectral sequence (O, B, A, F, G, etc. type stars) sorts stars according to
Group of answer choices
Rradius core temperature luminosity surface temperature.
The Correct Answer and Explanation is:
The correct answer is surface temperature.
Stars are classified according to their spectral characteristics, which primarily depend on their surface temperature. This classification system is known as the Morgan-Keenan (MK) system, and it categorizes stars into spectral types, such as O, B, A, F, G, K, and M, based on their temperature. Each spectral type represents a range of temperatures, from the hottest (O-type stars) to the coolest (M-type stars). The sequence is arranged as follows:
- O-type stars: These are the hottest stars, with surface temperatures greater than 30,000 K.
- B-type stars: These stars have surface temperatures between 10,000 and 30,000 K.
- A-type stars: Their temperatures range from 7,500 to 10,000 K.
- F-type stars: These stars are cooler, with surface temperatures between 6,000 and 7,500 K.
- G-type stars: These stars, including our Sun, have surface temperatures between 5,300 and 6,000 K.
- K-type stars: These are cooler still, with temperatures between 3,500 and 5,300 K.
- M-type stars: These are the coolest stars, with surface temperatures less than 3,500 K.
While other properties like luminosity, radius, and core temperature also vary across different types of stars, the primary criterion for this classification system is the surface temperature. Surface temperature directly influences the color and spectrum of light emitted by a star, which is why spectral types are closely tied to it.
The classification system also indirectly reflects other factors like luminosity and size (radius) because hotter stars tend to be larger and more luminous. However, the spectral sequence itself is fundamentally based on the star’s surface temperature, making it the most important characteristic for sorting stars in this context.