1) Use Google or some other search engine to find a range for the mass of a gian
ID: 152937 • Letter: 1
Question
1) Use Google or some other search engine to find a range for the
mass of a giant molecular cloud. Give your answer in multiples of
the Sun’s mass (for example ... 5 times the mass of the Sun).
Minimum estimate:
Maximum estimate:
2) Assume that 80 percent of this mass goes into forming stars, and
the average star mass is 1.5 times that of our Sun. For both
estimates from the first question, how many stars would be made
in each case?
Minimum estimate:
Maximum estimate:
Consider the following link for the next three questions:
http://www.messier.seds.org/open.html
3) Open clusters are large groups of stars that form from giant
molecular clouds. What are the highest and lowest mass stars
found in open clusters?
Highest mass stars:
Lowest mass stars:
Do you think that this makes our assumption in question (2) about
the mass of stars formed reasonable? Why or why not?
4) The link says that stars in an open cluster are roughly the same
distance away. In a few sentences, using the material from this lab
and the given link, how do we know this is the case?
5) The link also says that stars in an open cluster are roughly the
same age. Can the argument used for question (4) also be used to
argue they are the same age? Why or why not?
6) Remember that a star forms when a large amount of material
collapses under the influence of gravity. Once the star forms, it
releases energy outward in the form of photons. This will increase
the density of the molecular cloud near the newly formed star.
Explain how this happens in a few sentences.
7) Now that more regions of the molecular cloud are increasing in
density, would you expect this to lead to more star formation?
Why or why not?
8) Summarize in a couple of paragraphs how random motion and
gravitational collapse combine to convert giant molecular clouds
into open star clusters over a long period of time.
Explanation / Answer
Answer 1) mass of the sun is 1.989×10^30kg
. Minimum estimate= 10^3 times the mass of the sun
Maximum estimate =10^7 times the mass of the sun.
Answer2)
Minimum mass of giant cloud cluster= 10^3×1.989×10^30=1.989×10^33kg
Maximum mass of GMC= 10^7×1.989×10^30=1.989×10^37kg
Mass of the stars to be formed is = 1.5times the solar mass =1.5×1.989×10^30kg=2.9835×10^30kg
80% of the minimum mass of GMC= 15.912×10^32kg
80% of the maximum mass of GMC= 15.912×10^36kg
Minimum estimate of stars=5.3×10^2
Maximum estimate of stars to be formed=5.3×10^6
Answer 3
Highest mass star- Westerlund1 with mass of 5×10^4 solar masses
Lowest mass star-50times the solar mass
The assumption in question 2 was about the mass of the stars that are formed from the GMC, which was about 1.5times the solar mass. This assumption is not totally correct because the highest mass and lowest mass stars un open cluster is much more than what is given. There mass with respect to the solar mass varies greatly from 1.5 times
Answer 4) By studying Stellar Evolution from Hertzspeung Russel diagram for two open clusters, it is seen that stars in an open cluster are all at a roughly same distance from the earth. They are formed fromed at the same time from the same GMC. Their difference in apparent brightness is due to their difference in mass
Answer 5) The stars in an open cluster are at same distance from the earth as discussed in answer 4, evident from the Hertzspeung Russel diagram. The stars are also formed at the same time from the similar raw material, and thus they are similar in age. As the cluster ages,t he mass of the main sequence turnoff stars decreases. Thus by determining the mass of the main sequence turnoff star, we can find the age of the stars in the cluster. SSince all the stars in a cluster are same age, it can be determined easily.
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