This is a vocabulary word in textbook Astronomy Essentials by Michele M. Montgomery, Ph.D that contains Part 1 - Background and Basics on Apple Books: books.apple.com/us/book/id1590873139, Part 2 - Solar and Exosolar Systems on on Apple Books: books.apple.com/us/book/id1590877272, Part 3 - Sun, Space Weather, and Formation on Apple Books: books.apple.com/us/book/id1590879246, Part 4 - Stars and Stellar Evolution on Apple Books: books.apple.com/us/book/id1590881365, Part 5 - End Products and Binary Star Evolution on Apple Books: books.apple.com/us/book/id1590884825, Part 6 - Galaxies on Apple Books: books.apple.com/us/book/id1590887070
I would like to ask is that if the H-R diagram of a cluster has hotter and more luminous star in main sequence than one has less hotter and luminous , is that mean the cluster is younger ?
Since you are asking about younger or older and you mention the main sequence of the H-R Diagram, your question is about age of stars on the Main Sequence. The answer is that the higher up on the main sequence, the shorter the star's life. So yes, the cluster is younger the higher it is on the main sequence.
This is a vocabulary word in textbook Astronomy Essentials by Michele M. Montgomery, Ph.D that contains
Part 1 - Background and Basics on Apple Books: books.apple.com/us/book/id1590873139,
Part 2 - Solar and Exosolar Systems on on Apple Books: books.apple.com/us/book/id1590877272,
Part 3 - Sun, Space Weather, and Formation on Apple Books: books.apple.com/us/book/id1590879246,
Part 4 - Stars and Stellar Evolution on Apple Books: books.apple.com/us/book/id1590881365,
Part 5 - End Products and Binary Star Evolution on Apple Books: books.apple.com/us/book/id1590884825,
Part 6 - Galaxies on Apple Books: books.apple.com/us/book/id1590887070
I would like to ask is that if the H-R diagram of a cluster has hotter and more luminous star in main sequence than one has less hotter and luminous , is that mean the cluster is younger ?
Since you are asking about younger or older and you mention the main sequence of the H-R Diagram, your question is about age of stars on the Main Sequence. The answer is that the higher up on the main sequence, the shorter the star's life. So yes, the cluster is younger the higher it is on the main sequence.