Homework 7

For the problem below, the expectation is that you submit a standalone HTML file (any images should be embedded) back to GitHub. Data for the problem is provided in the starting repository in the /data folder. Since this is the third homework in this unit, groups have already been created, so just join with your group when you accept the assignment.

Accept Assignment

Problem: A Transitting Box

The idea for this problem is that you have an occasional periodic signal hidden within a large amount of noise. The file transit.csv has the data you are working with, which is mimicking brightness data from a transiting exoplanet. Here the brightness measurements have been approximately normalized around 1, representing the normal brightness emitted by the star when the planet is not crossing in front of it, but there is some variation present that you’ll need to address. You can take the time measurements to be in units of days.

Part A - BLS

• Following the BLS procedure, flatten the data and zero-center it
• Construct your BLS grid. You’ll need to decide on:
  • Minimum and maximum periods to look for, and convert to frequency
  • Frequency step sizes
  • The number of bins you want to subdivide the folded-signal into
  • Minimum and maximum durations to check (in fractions of normalized phase)
• Run the BLS. There are library functions provided to greatly assist with this in the repository.
• Construct a periodogram

Part B - Analysis

• Determine the peak frequency from your periodogram
• Visualize the folded signal, with a rolling average to help reduce the noise
• Estimate the depth of the drop and the duration of the drop from the rolling average visual
• Compute the depth of the drop and the duration of the drop directly from the peak s and r parameters, and compare to your visual estimates
• Assuming the star has a radius similar to that of our Sun (695,700 km), what is the radial size of the exoplanet? What Solar System planet would this size be most comparable to?