K-type Stars

Definition

K-type stars, also known as orange dwarfs, are a class of main-sequence stars that are slightly cooler and less massive than our Sun. They have a surface temperature range of 3,700 to 5,200 Kelvin and are characterized by their distinctive orange hue, which is a result of their relatively low surface temperatures compared to other stellar classes.

5 Must Know Facts For Your Next Test

1. K-type stars are less massive and cooler than the Sun, with a surface temperature range of 3,700 to 5,200 Kelvin.
2. K-type stars are the second-most common type of star in the Milky Way, making up about 12% of the total stellar population.
3. These stars are known for their distinctive orange hue, which is a result of their relatively low surface temperatures.
4. K-type stars have a longer main-sequence lifetime than the Sun, ranging from 15 to 30 billion years.
5. K-type stars are less luminous than the Sun, with an absolute magnitude range of 5.5 to 8.5.

Review Questions

• Explain the key characteristics of K-type stars that distinguish them from other stellar classes.
  • K-type stars are characterized by their relatively low surface temperatures, ranging from 3,700 to 5,200 Kelvin, which gives them a distinctive orange hue. They are less massive and less luminous than the Sun, with an absolute magnitude range of 5.5 to 8.5. K-type stars have a longer main-sequence lifetime, ranging from 15 to 30 billion years, compared to the Sun's estimated 10 billion-year lifespan. These characteristics set K-type stars apart from other stellar classes, such as hotter, more massive, and shorter-lived stars like O, B, and A-type stars, as well as cooler, less massive M-type stars.
• Describe how the spectral characteristics of K-type stars are used to determine their physical properties and composition.
  • The spectral lines observed in the spectra of K-type stars provide important information about their physical properties and chemical composition. The presence and strength of specific absorption lines in the star's spectrum correspond to the elements and their relative abundances within the star's atmosphere. By analyzing the spectral lines, astronomers can determine the surface temperature, luminosity, and even the age of a K-type star. For example, the presence of strong absorption lines from elements like calcium, iron, and titanium oxide in the spectra of K-type stars indicates their relatively cool surface temperatures and the abundance of these elements in their atmospheres. This spectral information is crucial for understanding the nature and evolution of K-type stars.
• Evaluate the significance of K-type stars within the context of the Hertzsprung-Russell diagram and their role in the overall stellar population of the Milky Way galaxy.
  • K-type stars occupy a specific region on the Hertzsprung-Russell (H-R) diagram, which is a graphical representation of the relationship between a star's luminosity and surface temperature. The placement of K-type stars on the H-R diagram, with their relatively low luminosity and surface temperature, helps astronomers understand their position in the overall stellar hierarchy and their role in the evolution of the Milky Way galaxy. As the second-most common type of star in the Milky Way, comprising about 12% of the total stellar population, K-type stars play a significant role in the galaxy's stellar composition and energy output. Their long main-sequence lifetimes also make them important contributors to the galaxy's ongoing stellar activity and the chemical enrichment of the interstellar medium over cosmic timescales.

Related terms

Main Sequence: The main sequence is the band where most stars spend the majority of their lives, fusing hydrogen into helium in their cores.

Stellar Classification: The system used to categorize stars based on their spectral characteristics, which are determined by their surface temperature and chemical composition.

Spectral Lines: Absorption lines in a star's spectrum that correspond to specific elements and provide information about the star's composition and physical properties.