tha very last 3 dot points in this module... (1 Viewer)

[cko]

1) present information by plotting H-R diagrams for: nearby or brightest stars, stars in a young cluster, stars in a globular cluster.

2) analyse information from a H-R diagram and use available evidence to determin the characteristics of a star and its ecolutionary stage.

3) present information by plotting on a H-H diagram the pathways of stars of 1, 5 and 10 stellar masses during their lifecycle.

i got som info from school but i don't quite understand them coz they're just notes and i need someone to explain...

 

[mcstump]

1) stars in younger clusters tend to be mostly on the main sequence, with the more massive stars branching off to the right ie red/supergiants the age of the cluster can also be determined by the age of the highest star remaining on the main sequence.

2) characteristics of different stars can be determined by their original mass at the point where they entre the main sequence. (ZAMS)

3)~1 solar mass stars live longest on the main sequence but arent hot enough to eqperience helium flash. they go straight to white dwarf
~5 mass stars will be hot enough (after initial colapse) to burn helium. they go to red giants and continue to burn helium then go to white dwarf after the planetary nebula (have to get below that blokes limit [1.4 approx])
~10 solar mass stars will go thru proton-proton cycle, helium flas as a red giant, colapse gain heat and go thru CNO cycle, if large enough after that the colapse, gain heat and burn succesive elements up to iron. once they reach that there is no energy gain in tha core, core collapses, outer star colapses and as core rebounds and bounces out it creates supernove (hot enough to meke higher elements [gold, uranium]) if the mass is < 3solar masses at this stage it has high enough grav to form neutron star (gravity puls electrons and protons together). if it is > 3 solar masses, gravity overcomes neutrons to form black hole.

hope this helps

 

[helper]

3 1 solar mass stars like the sun are expected to reachthe red giant phase and do experience a helium flash.
However lower mass stars don't and drop to white dwarf.

The two websites are good simulations of the paths of stars. The first lets you select star mass and observe its motion across the HR diagram. Sadly it doesn't do the exact ones in the syllabus
http://instruct1.cit.cornell.edu/courses/astro101/java/evolve/evolve.htm

The second by selecting a few hundred stars and evolving them shows the evolution up to the red giant phase. The original plot is what is called the zero age main sequence. Similar to what you see in an open cluster.
As it evolves you can see how the turn off point from the main sequence drops. From the location of this turn off point the age can be determined. Also you can note over time the more massive stars dissapear first. So from the distribution of the stars you can approximate an age.

 

[jang]

helper bro, srsly ur the most astrogenius i ever seen...
do u hav notes? i have notes.... but u think im dumb dont u... dont u! how could u!
orite. well yeh, im always here if u need a swap ^_~

 

[helper]

I make no judgements on intelligence. The more often you go over the stuff the more questions you have. The more you will eventually know. Ask no questions learn nothing.

 

[jang]

I make no judgements on intelligence. The more often you go over the stuff the more questions you have. The more you will eventually know. Ask no questions learn nothing.

ah yes. thank you helper.
i just did a full day work on physics... but only covered first 3 sections of space (+ a past paper for which i have so many q's)... i'll be back if i cant see answers to these q's on this forum :/