Physical Properties Of Galaxies Lab Report
Jordan Toschak
Kevin Hannon and Megan Blanford
Physical Properties of Clusters of Galaxies
Monday (4/15/2013)
Procedure
For this experiment, a photograph of the Virgo Cluster of Galaxies will be needed to observe.
The photograph will be sectioned into specific areas with coordinates like a map. Locate the area and identify the galaxies. Classify the galaxies as elliptical, spiral, or irregular.
An elliptical galaxy will appear solid with not real defined “arms” or spirals coming from the center. An elliptical galaxy can be further classified E0 through E7 depending on the eccentricity of the elliptical. An elliptical galaxy with an E0 classification will be primarily rounded while an E7 will be remarkably eccentric. The classifications in between vary accordingly. …show more content…
A spiral galaxy will appear with a defined center or “bulge” with arms spiraling from the center.
These classifications range from Sa to Sd. An Sa galaxy will have a large bulge with weak or small arms, an Sb galaxy will have a medium bulge and medium arms, an Sc galaxy will have a small bulge with large arms, and an Sd galaxy will have a bulge that isn’t clearly defined, but the stars are patterned in a circular manner.
An irregular galaxy won’t look like any of these things, but there is a definite clump of stars.
In addition to classifying each of these galaxies, measure the longest distance across the galaxy using the millimeter scale and the magnifying glass. If there is more than one galaxy in the coordinated area, measure each of them and average their sizes.
Finally, average the apparent sizes of each of the spiral galaxies and use this measurement to determine the approximate distance to the Virgo Cluster of Galaxies using the equation Distance=2.2 million lightyears×78 mmN mm with N representing the average size of all of the spiral galaxies.
Compare your results to the theoretical value D=16 Mpc (Mega parsecs)
Use the conversion facts 1 pc=3.26 ly and 1 Mpc=
10X10⁶
Questions
What assumptions have been made to determine the mean distance?
The assumption is being made that all normal spiral galaxies are all roughly the same size. Assuming this, one can determine the approximate distance to any normal spiral galaxy if you know the true size of just one galaxy.
Why could these assumptions produce the wrong answer?
Assumptions can always produce the wrong answer. If the assumption that all normal spiral galaxies are roughly the same size proves to be incorrect, then the formula used in the experiment will be invalid. The number 78 mm is an assumed measurement of average spiral galaxy size.
Conclusion
The purpose of this lab was to determine physical characteristics of the Virgo Cluster of Galaxies, specifically to classify galaxies according to physical properties and then determine the distance to the Virgo Cluster. In our experiment we found that the distance was 18.34 Mpc compared to the theoretical value of D=16 Mpc we had a 14.6% error. This errors may have resulted in human error. The galaxy was classified wrong or the measurement recorded wasn’t correct to the .1 mm. We may have assumed something was a galaxy when in reality it was a misprint or point of damage on the image. This lab was relevant because it provides us with a method to determine distance to clusters of galaxies based on an inverse proportion.
Kevin Hannon and Megan Blanford
Physical Properties of Clusters of Galaxies
Monday (4/15/2013)
Procedure
For this experiment, a photograph of the Virgo Cluster of Galaxies will be needed to observe.
The photograph will be sectioned into specific areas with coordinates like a map. Locate the area and identify the galaxies. Classify the galaxies as elliptical, spiral, or irregular.
An elliptical galaxy will appear solid with not real defined “arms” or spirals coming from the center. An elliptical galaxy can be further classified E0 through E7 depending on the eccentricity of the elliptical. An elliptical galaxy with an E0 classification will be primarily rounded while an E7 will be remarkably eccentric. The classifications in between vary accordingly. …show more content…
A spiral galaxy will appear with a defined center or “bulge” with arms spiraling from the center.
These classifications range from Sa to Sd. An Sa galaxy will have a large bulge with weak or small arms, an Sb galaxy will have a medium bulge and medium arms, an Sc galaxy will have a small bulge with large arms, and an Sd galaxy will have a bulge that isn’t clearly defined, but the stars are patterned in a circular manner.
An irregular galaxy won’t look like any of these things, but there is a definite clump of stars.
In addition to classifying each of these galaxies, measure the longest distance across the galaxy using the millimeter scale and the magnifying glass. If there is more than one galaxy in the coordinated area, measure each of them and average their sizes.
Finally, average the apparent sizes of each of the spiral galaxies and use this measurement to determine the approximate distance to the Virgo Cluster of Galaxies using the equation Distance=2.2 million lightyears×78 mmN mm with N representing the average size of all of the spiral galaxies.
Compare your results to the theoretical value D=16 Mpc (Mega parsecs)
Use the conversion facts 1 pc=3.26 ly and 1 Mpc=
10X10⁶
Questions
What assumptions have been made to determine the mean distance?
The assumption is being made that all normal spiral galaxies are all roughly the same size. Assuming this, one can determine the approximate distance to any normal spiral galaxy if you know the true size of just one galaxy.
Why could these assumptions produce the wrong answer?
Assumptions can always produce the wrong answer. If the assumption that all normal spiral galaxies are roughly the same size proves to be incorrect, then the formula used in the experiment will be invalid. The number 78 mm is an assumed measurement of average spiral galaxy size.
Conclusion
The purpose of this lab was to determine physical characteristics of the Virgo Cluster of Galaxies, specifically to classify galaxies according to physical properties and then determine the distance to the Virgo Cluster. In our experiment we found that the distance was 18.34 Mpc compared to the theoretical value of D=16 Mpc we had a 14.6% error. This errors may have resulted in human error. The galaxy was classified wrong or the measurement recorded wasn’t correct to the .1 mm. We may have assumed something was a galaxy when in reality it was a misprint or point of damage on the image. This lab was relevant because it provides us with a method to determine distance to clusters of galaxies based on an inverse proportion.