Galaxies Lab

In this lab, we examined and classified several different types of galaxies. By doing this, we will be able to reference certain galaxies without having to view them based on their structure and content.

A
1. A description of a spiral galaxy would be that is has an obvious bulge at the center, and spiral arms that reach out from this bulge in a plane. An elliptical galaxy is round in shape, but has no other distinct features, except maybe a brighter center.
2. The larger galaxies in the Virgo cluster tend to be elliptical galaxies, because they have no defined features and are round in shape.
3. The smaller galaxies in the Virgo cluster are spiral galaxies.
4. NGC 4438 probably looks this way because the gravity of the nearby galaxy is pulling at its shape and causing it to look irregular.
5. NGC 4388 is an SBc galaxy with a flat, spiral appearance.

NGC 4413 is an Sc galaxy with an ovular shape, and it is seemingly flat.

NGC 4402 is an E7 with an elongated main portion and no visible center.

NGC 4374 is an E0 spherical galaxy.

NGC 4425 is an S0 that flat with a few slight arms.

6. In the Hercules Cluster, the most obvious galaxies that occur are elliptical and spiral.
7. In finding the distances to the Hercules and Virgo Cluster, it would be best to use cepheid variable stars. If this doesn't work, one could also look at the apparent brightness of a cluster's main sequence star, which can tell us the distance. A formula for this would be

                                distance= luminosity/√ 4π (Brightness)
8.
Korenphoros is a main sequence star in the Hercules galaxy. By using the above formula, we can find the distance in lightyears.
distance= 175lSun/√ 4π(2.77 mag)
distance=148 ly

B
1. The following images are various types of galaxies seen with the Hubble Ultra Deep Field image.

Spiral Galaxy

Elliptical Galaxy

Irregular Galaxy

2. The elliptical galaxies in the HDF look far more sparse than in the Virgo and Hercules clusters.
3. I believe that spiral galaxies are the first to become mature of the spiral and elliptical galaxies. This is because it is only after the collision of two spiral or other smaller galaxies that an elliptical will form.
4. Most of the irregular galaxies are blue, meaning that they are still a site of young star formation. Most of the elliptical galaxies are yellow, meaning that older stars are located here. This means that there is less young star formation occurring here.
5. In the images of the clusters, there seems to be a lack of irregular galaxies.
6. The fact that there are little to no irregular galaxies in theses clusters means that irregular galaxies only form within very young clusters.
7. The picture below displays how many galaxies would appear in the whole sky if the Hubble Space Telescope took a deep field image of the entire thing.

In conclusion, there are millions of galaxies in the night sky, but only a few classifications that they can all be funneled into. This classification can be done with the Hubble tuning fork diagram, which displays each type of galaxy in all of their forms. By examining galaxies, we get an idea of true expanse of the universe and what may lie millions of lightyears away.