What event marks the main-sequence turnoff point on an H-R diagram for a cluster?
Answer
Stars beginning to evolve off the main sequence after exhausting core hydrogen
The main-sequence turnoff point identifies the most massive stars that have consumed all the hydrogen in their cores and have started evolving toward the red giant phase, signaling the cluster's age.
Frequently Asked Questions
What fundamental property dictates a star's fuel consumption rate and lifespan?What relationship is plotted on the Hertzsprung-Russell (H-R) diagram to aid in stellar aging?Why are star clusters considered reliable natural laboratories for determining stellar age?What event marks the main-sequence turnoff point on an H-R diagram for a cluster?If the turnoff point in a cluster corresponds to stars five times the mass of the Sun, what does this imply about the cluster's age?What major factor introduces greater uncertainty when dating a single, isolated star compared to a cluster?What type of 'clock' dictates the aging process for a planet like Earth, contrasting with stellar dating?How does a star lose angular momentum over time in the process known as gyrochronology?What physical phenomenon does asteroseismology analyze to determine a star's interior structure?What specific internal feature provides a direct age signature when using asteroseismology on a hydrogen-fusing star?