lab 8 report (1) filled out
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103
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Astronomy
Date
Apr 3, 2024
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Properties of Galaxies
12/11/2022
Grouping Galaxies Based on Appearance
1. When you have sorted the galaxies to your satisfaction, save a JPG-format copy of the mosaic and add it to your lab report here.
Place your JPG-format image of the sorted galaxy mosaic here.
2. Add a detailed explanation which describes the key properties of the
galaxies assigned to each row of your mosaic (such as “Row #1: Galaxies have a uniform golden color, no clear features or substructures, and elliptical shapes.”). If there were particular cases which you found most perplexing (such as a galaxy that seemed to belong equally well to two rows), make a note of them as well. (For example, “The last galaxy on the right in row #2 could have gone in row #3 as well, if I prioritized shape over color.”)
Replace this text.
3. Save a JPG-format copy of your partner's mosaic and add it to your lab report.
Place your partner’s JPG-format image of the sorted galaxy mosaic here.
4. Describe your sorting partner. Are they a man or a woman, or a boy or a girl? (If a child, please tell us their age.) Are they engaged in a profession where attention to detail is critical (such as seamstress or electronics technician), or are they Big Picture people? Are they color blind? Have they ever looked at pictures of galaxies before? Sorting partner is a female. They are not in a profession that requires attention to detail. She is not color blind and has never intentionally looked at pictures of galaxies before.
5. Describe the differences and the similarities between your two final galaxy mosaics. Did you agree broadly, or did you focus on very different aspects of the images? Can you each understand what the other did?
We agreed broadly, and I grouped them by shapes and size. She mostly used color and I can see why each of us did that Galaxy Morphology Questions
Please remove incorrect choices, as well as surrounding parentheses and slashes, in the questions below (and delete this instruction).
1. A galaxy emitting lots of blue light must contain many ( hot), (
high-) mass ( long- ) lived stars. The stellar classification
of these blue stars is ( O and B )
.
2. Galaxies which appear more disturbed tend to have ( higher )
asymmetry indices, and (
bluer
) colors.
3. Elliptical galaxies tend to be ( redder ), ( more ) massive,
and contain ( less ) gas than spiral galaxies. Their concentration
indices are ( higher ), while their asymmetry indices are ( lower ).
4. The Milky Way is a replace this text galaxy, with a sub-classification of ( Sb ). It also has a central bar
5. It is much easier to trace the spiral arm structure on a(n) ( fa
ce-on ) spiral galaxy than on a(n)
( edge-on ) one.
6. The force which binds all of the stars and gas in a galaxy together is the
Gravitational force. Imaging Tool Questions
1. Save a copy of the final galaxy data table and include it in your lab report. Place your JPG-format table of galaxy imaging data here.
2. Note the “ripples” that appear at large radii in the radial counts profile for Galaxy #1. What do
you think causes them?
The distribution of light is represented by the ripples.
3. Galaxy #1 Comments: no bar or spiral arms.
4. Galaxy #2 is far less luminous than our Milky Way. How many galaxies of this luminosity would you need to match the light output of the Milky Way?
About 20 galaxies 5. Notice how the light profile (the radial plot of counts) can be divided into
an inner region and an outer region (with a change of slope between them). The names for the two galaxy components that these two regions represent are the inner circle and the outer circle.
6. What do you think causes the patches of blue in the outer regions of this galaxy?
I think the formation of new stars is the cause of the patches of blue in the outer regions. Along with dust clouds and blue stars 7. Galaxy #2 Comments
: this galaxy is smaller than the other so my guess is that its younger than the others. Faint blue 8. Does Galaxy #3 have a fairly uniform color? ( yes )
9. Galaxy #3 Comments: its hard to make out the other stars in this one, and it looks like there is a core 10. Consider the total B-V color measured across all of Galaxy #4. What value do you find if you reduce the size of the ellipse to contain just the bright golden nucleus of the galaxy? What types of galaxies have this B-V color overall?
Ellipitcal galaxies
1.06 B-V.
11. Galaxy #4 Comments: I would call this core bright yellow and it has lots of blue stars in it. Looks like a clear spiral galaxy too 12. What do you think this object (Galaxy #5) might have looked like a few billion years ago?
My guess is it would have looked like a spiral galaxy
13. Galaxy #5 Comments: This is definitely one of the larger ones
.
14. Note the dark band running along the disk of Galaxy #6, and the bright splotch slightly offset
from the center as defined by the rest of the galaxy. These factors will lead to a ( lower ) asymmetry index. 15. Galaxy #6 Comments: ellipitical and uniform gold coloring 16. Does the edge-on orientation of Galaxy #7 make it more difficult for us to calculate an asymmetry index, and to define a morphological type?
Yes, the edge-on orientation makes it more difficult
17. Galaxy #7 Comments: it’s hard to see the whole galaxy entirely. Cloudy
18. A larger neighboring galaxy above our target (Galaxy #8) scatters light across this entire
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image. Because of this, the ( right ) side of the radial profile is slightly higher than it should be.
19. Galaxy #8 Comments: this one looks a little smaller and I would guess that it’s an older galaxy in close proximity of another galaxy. Bright yellow nucleus 20. Galaxy #9 Comments: I am guessing these are older because they are orange.
21. Galaxy #10 Comments: this looks like a newer spiral galaxy because the grooves are not as tight. Blue uniform coloring
22. Which of the ten galaxies posed the largest challenge to fit? Which was the easiest to analyze? Explain your choices.
Galaxy 1 was the easiest to fit because the lines were more defined
Galaxy 8 was the hardest for me because it was harder to shrink down Spectral Tool Questions
1. Save a copy of the final galaxy data table and include it in your lab report. Place your JPG-format table of galaxy spectral data here.
2. The presence of which very strong emission line in the Galaxy #1 spectrum rules out the “E” (for elliptical) morphological class?
Replace this text
.
3. Is it the presence or absence of key absorption or emission lines, or the poorly fitting shape of
the continuum (the overall shape of the spectrum, ignoring emission and absorption features) which rules out the Sc, Sd, and interacting galaxy types?
Presence of emission lines rule out the sc/sd and interacting galaxy types.
4. Describe the general pattern formed by the galaxy spectrum and the type-specific spectra when the correlation coefficient drops below 0. For which galaxy types does this occur, for this galaxy?
Spikes of flux and magnitude are the general patterns formed by the galaxy spectrum.
5. What morphological type yields the second-highest correlation coefficient? Can you point to a feature shown in the accompanying galaxy image which also suggests that this is not the
correct type?
The spiral galaxy type yields the second highest correlation coefficient
6. Galaxy #1 Comments: more red with blue spots.
7. More distant galaxies appear ( smaller
) on the images, and their observed spectra are shifted
to the ( right ) to ( longer ) wavelengths.
8. If we took a second spectrum of Galaxy #2 and sampled a small region near the galaxy edge rather than the nucleus, how would you expect the spectrum to change? The (
emission ) lines would become much stronger, indicating ( increased ) star formation in this region of the galaxy.
9. Galaxy #2 Comments: 2 spiral arms with blue in the arms
10. The redshift measured for Galaxy #3 confirms that it appears so small in the image because
it is ( very far away
).
11. Galaxy #3 Comments: elliptical, and bright yellow coloring .
12. Galaxy #4 Comments: difficult to see but it looks like blue arms and yellow coloring .
13. Galaxy #5 was very easy to type based on its image, but should give us a different answer based on its core spectra alone. Why is this the case?
I think this is because it’s a Sa type galaxy and because of the emission lines.
14. Galaxy #5 Comments: two spiral arms and some blue and yellow coloring .
15. Galaxy #6 Comments: elliptical and yellow coloring with some strange object towards the middle 16. Many galaxies of the same morphological type as Galaxy #7 have ( bluer ) disks.
17. Galaxy #7 Comments: looks more red than it usually does 18. Are both of the galaxies in the Galaxy #8 image of the same type? ( yes
)
19. Galaxy #8 Comments: elliptical and yellow coloring .
20. Galaxy #9 Comments: yellow coloring with a strange object near the middle 21. Can you identify a single feature which is very strong in the observed Galaxy #9 spectrum but much weaker in the reference spectrum for this type of galaxy? How would you expect this
to affect the correlation coefficient?
Theres a spike in #9 that is very strong. 22. Galaxy #10 Comments: blue in the arms and yellow coloring .
23. Which of the ten galaxies posed the largest challenges in determining redshifts? Which was
the easiest to fit? Explain your choices.
I thought Galaxy #10 was challenging because I couldn’t get a full correlation and it was the only
galaxy type of its kind. Galaxy #8 was the easiest because I was able to get almost a full correlation. Final (Post-Lab) Questions
1. Given what you now know, describe how you grouped galaxies together initially. (To what galaxy properties were you most sensitive?)
I grouped them based on their shape and size.
2. If you were to resort these galaxies now, what would you change? Are there aspects which you emphasized which you now think are unimportant? Are there properties which you dismissed which now seem more important, in view of what you have learned?
If I were to do it over again I would pay more attention to the type of galaxy they belonged to instead of their shape and size. I would also pay more attention to the which ones were spiral galaxies. 3. What are the basic observed properties of elliptical galaxies, in images and in spectra? What
does this tell us about the distribution of stars and gas in these galaxies?
Elliptical galaxies are more red and gold colored and look like an oval, and they are bigger in size. The distribution of stars tend to be more condensed towards the middle and that leads to less stars forming and less gaseous galaxies
4. What are the basic observed properties of spiral galaxies, in images and in spectra? What does this tell us about the distribution of stars and gas in these galaxies?
The typical spiral galaxies are blue and contain hot stars. There are new stars being formed more consistently since there is more matter. The distribution of stars is wide spread and more gaseous compared to elliptical galaxies. 5. Which of the ten galaxies in our sample is the best match to the Milky Way galaxy, and why?
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In my opinion I would say Galaxy #1 is the best match to the Milky Way galaxy. The colors seem to match and the spiral shape looks pretty close to the Milky Way. 6. Compare your derived morphological types based on images and then from spectra for the ten sampled galaxies. For which galaxies did you estimate different morphological types from the image and from the spectrum? Where your type estimates differed, did they differ by one step (Sb versus Sc), or by several steps (E versus interacting)?
We estimated different morphological types on galaxies 1, 5, and 10. Most differences I saw were by one step (sb vs sc).
7. Consider the galaxies for which you found the greatest disagreement between image-based types and spectrum-based types. Discuss the cause(s) of the differences, and explain which type classification you think is the most accurate in each case.
The greatest disagreement between image-based types was with galaxy #10. It was hard to see
the other nucleus in this one so that was challenging as well Summary (300 to 500 words)
It was very interesting to look at each type of galaxy and see what their differences are. You do not think about how colors and shapes may differ from galaxy to galaxy but they are very different. At first, it was hard figuring out the type of galaxies, but labeling the galaxies at the beginning turned out to be helpful in the end. I personally had trouble using the web application, trying to line up the galaxies was not easy for me. I think the goal of this lab was to come to an understanding that the how big the universe really is and how much more is out there. Galaxies on galaxies exist that make us feel small in comparison. To accomplish this goal we studied date and pictures of galaxies' luminosities, color, size and morphologies. This way we got some hard numbers but we also have to see the differences as well.
There are many different types of galaxies that have different characteristics. There are elliptical galaxies that are shaped like an oval and appear round when you look down at them. Then there are spiral galaxies that have thin round disks, spiral arm, and can look flat from certain angles. There are Lenticular galaxies have some of the same qualities of elliptical and spiral. They seem to be the most challenging to classify because there is no particular shape. There is also peculiar and interacting galaxies that are are non-symmetric shapes and indicate galaxies.
Each of these galaxy types have different gas content and holster different stars and different formations. The Elliptical stars are clustered together in the middle, and look gold and red. The red and gold coloring means there is no recent star formation and there is less gas there. The Spiral galaxies are very blue in the arms, meaning they have new star formation. There
is also less gas here, but still more than the elliptical galaxies. The lenticular galaxies have no gas and no have no recent star formation, meaning there is no blue coloring. The interacting and peculiar galaxy types have uncommon structures, shapes, and colors. The gas content can vary between interacting galaxies even if it is transferred.
I thought the hardest part of this lab was the determining the morphological types using the 10 samples. Sample number 10 was challenging because it looked like a spiral galaxy at first. As we looked into it more, you could see it belonged with the interacting galaxies. This can be confusing at first but you cannot just trust the appearance of the galaxies. Extra Credit
The goal for this project is to make a map of the universe! You can take a short but picturesc simulation tour through the universe using the information gathered by the SDSS. It would be very cool to have an actual map of the universe, even though it would take light years to get to places. Something about having a map makes you feel like you can get there, which makes it feel that much more real. The SDSS telescope is located at the Apache Point observatory in new mexico. Scientist have found over 100,000 quasars using the sdss