Computational assesment

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School

University of New South Wales *

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Course

3160

Subject

Astronomy

Date

Dec 6, 2023

Type

docx

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Uploaded by mbckafido on coursehero.com

Approach Data gathering: Data Gathering:  GAIA Data : Obtain data from Vasiliev & Baumgardt (2021), Table A1. Ensure you have all 170 rows. Choose a data format that works best with the tools or programming languages you're familiar with.  Harris Catalogue Data : Use the provided .csv or .txt versions of the reformatted Harris tables. 3. Data Merging: Since you'll be working with data from two sources, you'll likely need to merge or join them based on a common identifier, probably the cluster name or some identifier. 4. Data Exploration:  Inspect the data for any inconsistencies, missing values, or outliers.  Generate basic statistics (like mean, median, mode) and visualize the data to understand the distribution of the proper motions and recession velocities. 5. Analysis:  Direction of Rotation : By plotting the proper motions against the positions of the clusters (from the Harris Catalogue), you should get an idea of any general movement patterns. A trend might indicate a preferred direction of rotation.  Amplitude of Rotation : If a preferred direction of rotation is observed, calculate the magnitude of this rotation.  Velocity Dispersion : This is essentially the spread of velocities about the mean velocity. You can calculate this using standard deviation.  Combining Proper Motions and Recession Velocity : You can use vectors to represent both velocities and then combine them to get a total velocity vector for each cluster. This will provide a comprehensive picture of each cluster's movement in three dimensions. 6. Interpretation and Conclusions:  Based on the analysis, draw conclusions about the rotation of the Milky Way's globular clusters.

 Discuss the implications of your findings on the formation of the Milky Way and its globular cluster system. 7. Further Analysis:  Suggest additional tests or studies that could further elucidate the formation scenarios of the Milky Way. For instance, studying the age distribution of clusters might provide clues about when they formed relative to significant events in the Milky Way's history. 8. Documentation: Given the emphasis on clarity and the ability for someone else to follow your logic:  Clearly comment your code to describe what each section is doing.  If possible, divide your analysis into sections or steps with headers.  Write an accompanying report or document that explains your approach, methods, findings, and interpretations in plain language. Include visual aids, such as graphs or plots, to support your conclusions. Important Aspects:  Clarity : Your logic should be easy to follow.  Documentation : Each step should be well-documented so that another person could reproduce your results.  Interpretation : The real value of this assignment is in drawing meaningful conclusions from the data. The technical side is important, but understanding and interpreting your findings are crucial. Approach:  Start with a clear plan: Understand the data sources, the tools at your disposal, and the final objectives.  Tackle the assignment step by step, ensuring you understand and can explain every decision and method you choose.  Document as you go, making sure everything is clear and easy to follow. Remember, the emphasis is on clarity and interpretation, so make sure to prioritize those throughout the process!

I have found out that when I plotted proper motions of glob. cluster in MW (Declination against ascension), I got a pattern of clusters that are accumulating on the right bottom part of the graph (90%) and the rest is spread randomly. Also most clusters point downwards, which should indicate a consistent pattern of preferred direction of rotation. The Magnitude of rotation is 5.11 mas/yr using the formula: sqrt(pmRA^2 + pmDE^2). What does this mean? Next I computed the mean velocity and the standard deviation: Mean Recession Velocity: -4.65 Velocity Dispersion: 141.85 and plotted a graph of X,Y,Z coordinates and got the image of all globular clusters on a 3D plot with vectors representing recession velocities, where half of the clusters point upwards and half of them downwards. What does this mean? The motion of globular clusters in relation to the Milky Way galaxy provides valuable insights into the galaxy's history, formation, and evolution. Here's a possible interpretation of your results, keeping in mind the data and the characteristics you've observed: 1. Origins and Formation of Globular Clusters : Globular clusters are ancient structures that can predate the formation of their host galaxies. The 50-50 split in motion suggests a bimodal distribution of movements. This could indicate that half of the clusters originated in the Milky Way, while the other half might have been captured from smaller galaxies or other structures that the Milky Way interacted with or merged with in its past. 2. Milky Way's Evolution : The globular clusters pointing upwards and downwards may be influenced by the gravitational pull of the Milky Way's central bulge and dark matter halo. Their motion can shed light on the Milky Way's gravitational potential and the distribution of its dark matter. 3. Peculiar Motions & Interactions : If certain clusters do not conform to the observed patterns and have peculiar motions, they might be recent captures or could have experienced interactions with other clusters or structures in the Milky Way, which altered their trajectories. 4. Future of Our Galaxy : The motions of the clusters can be extrapolated to predict future interactions. For example, clusters moving towards the center of the Milky Way may eventually be absorbed by the central bulge. Conversely, clusters moving outwards might escape the galaxy's gravitational pull if they attain sufficient velocity. 5. Evidence of Past Mergers : The Milky Way has undergone several mergers with smaller galaxies throughout its history. The motion of

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