Click here if you are having trouble logging into the forums
Privacy Policy |
Please read our Terms
of Service | Signup and
Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User
**DONOTDELETE**
|
|
Besides measuring the radioactive decay of certain elements in stars, is there another way to determine, or guestimate, the age of stars? I was volunteering in the Grand Canyon and telling people the globular clusters are some of the oldest stars of our galaxy as I have read in more than one source. Someone asked me how we know how old stars and my answer was much more simple than I wanted. Thanks for any feedback.
|
rboe
Numbfinger
Reged: 03/16/02
Posts: 39479
Loc: Phx, AZ
|
|
Glad you didn't ask a real hard question like how do we know how far away they are (Rand McNally)!
I would recommend Scientic American for past articles. They are relativly easy to read without the need for a physics degree. For some stars there a simple answers, for others it gets a bit more complicated. I'm way out on thin ice myself so hopefully someone a little closer to the subject in time and place will voluntee an answer.
Ron
--------------------
Ron
NS11GPS
Pronto
16" dob
15X70 Obies
|
Anonymous
Unregistered
|
|
Stellar Lifetime:
Luminosity is the total power output of a star. Power is the rate of producing energy or the rate of using energy. The source of energy in a star is the conversion of mass into energy. Using Einstein’s equation, E=MC Squared.
Therefore, luminosity is proportional to the mass divided by the lifetime. Using units of solar luminosity and solar mass, and the lifetime of our sun (10 billion years): T=10x(M/L) in billions of years. The mass-luminosity relation shows that luminosity is proportional to the mass raised to the 3.5 power. Lifetime then is proportional to one over mass raised to the 2.5 power. T=10/M 2.5 pwr. in billions of years (M in units of solar mass)
The Hertsprung-Russel diagrams can be useful for a general overview if precise age is not required. Put simply, the more massive the star, the faster it burns fuel, and the faster it moves off the main sequence.
I'm a little rusty at this stuff. I used to study it quite a bit when I was younger. A very good book which I'm sure is out of print by now, "The Life and Death of Stars" is an intermediate to advanced intermediate astrophysics book
that explains in detail just what the title says. You don't have to be Einstein to understand it either.
I'm at work right now, but if you are interested I can post the ISBN number for you if you wish to search for a copy or check your local library. Fascinating reading.
|
**DONOTDELETE**
|
|
Thank you both for your responses. When I take my time with what your wrote  It makes a lot of sense. On another thread (space.com ask an astronomer) the answer discussed cross sectional study of stars in various stages of life...such as observing human beings in various stages of life. Your answers and that put together help quite a bit.
|
rboe
Numbfinger
Reged: 03/16/02
Posts: 39479
Loc: Phx, AZ
|
|
Moby;
I got to the online Scientific American to do a quick search and found you have to subscribe at $35.00 a year to access that - from what I could tell. A bit of a bummer.
I'll see if I can search the last year or so from my hard copies for relevant articles. I have read several good ones recently. While "No APO" Schultze did a very nice job with his description, he didn't have any pictures. 
What good is that?  From the magazine you get nice pictures, even if they don't help. 
In the mean time; I have had good luck on university sites for similar problems (e.g. galaxy formation,mechanics of). University of Arizona would be a good site to start with.
Ron
--------------------
Ron
NS11GPS
Pronto
16" dob
15X70 Obies
|
Anonymous
Unregistered
|
|
"The Life and Death of Stars", Donald A. Cooke, 1985 Crown Publishers. ISBN 0-517-55268-X
This book is not in print but is available from Amazon.com as a used volume. There are several available in good to collector condition. I didn't see any over $20. Well worth it if you're into this stuff like I am.
The Life and Death of Stars
|
|
1 registered and 2 anonymous users are browsing this forum.
Moderator: matt, Olivier Biot
Print Thread
|
Forum Permissions
You cannot start new topics
You cannot reply to topics
HTML is disabled
UBBCode is enabled
|
Thread views: 661
|
|
|
|
|
|
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
