If a star is floating alone in space....?

Question

I observe a star that is freely floating in space and is not part of any star cluster. This star is a K type red giant, and when I observe its spectrum, its chemical composition is similar to the stars in a globular cluster.

Do you think this star is older or younger than the Sun? How do you know it?

What do you think is the origin of this star, that is, what type of system was it a part of when it formed?

Answer 1

A red giant would be older than our sun, which is still on the main sequence.  How do I know?  From the H-R diagram.  Main sequence stars like our sun are still fusing hydrogen at their core.  Red Giant stars have exhausted (used up all of) the hydrogen at their core, and thus the process moves further out in the stars shell, causing it to expand and cool.  

As for the origin, most stars are born (form) in clusters as protostellar clouds collapse and material clumps together.  

Also, most stars are found in binary or multiple systems.  Single stars like our sun are the exception, not the rule.  However, even our sun formed with a group of stars, it has just slowly drifted away from them.

Answer 2

Sun is G.  Expected to spend a total of 10 billion years on main sequence before going "red giant" on us. Sun still has 5 billion years to go.

K star is less massive than Sun.  Therefore expected to have a longer life on the main sequence.  If it is already red giant, then it has to have started off at least 5 billion years before the Sun, probably even more.  Therefore it is much older than the Sun.

Globular cluster stars are usually poor in "metals" (what astronomers call any element heavier than helium).  That is because they were created before the heavier elements were made.  

Therefore, this is another sign that your K star was born before our Sun.  Our solar system obviously contained lots of heavier elements because that is what our Earth is made from (the "dust" that was in the giant cloud that collapsed to form our solar system).  This makes our Sun one of the young kids in the universe.

Answer 3

Younger, cause I feel that there's not many "things" out there that are older than our sun.  Aren't "red giant's" the end results of a star finally blinking out---how were you able to see this star, cause I thought that red giants are really faint.  And that the "red giant" phase of a star is really short (in human terms), of course in intrastellar terms the phase is very long like several million years!

Answer 4

When two galaxy are merging some of the stars will get rejected out of the newly form galaxy.. It think that was happened to that lone star..