Exoplanet Habitability & Demographics

Skills:

Queried and processed large-scale exoplanet datasets from NASA Exoplanet Archive using TAP and SQL
Developed layered, multivariate, color-coded visualizations in Python to highlight key demographic clusters and habitable candidates
Modeled stellar flux to assess exoplanet energy budgets and potential habitability zones
Interpreted exoplanet demographic trends (such as radius–temperature distributions) to assess habitability, atmospheric retention, and selection biases
Studied atmospheric escape processes (such as Jeans escape, energy-limited loss) and their dependence on planet radius and stellar flux
Classified habitability regimes using empirical thresholds for radius and equilibrium temperature

I used NASA Exoplanet Archive to analyze trends in atmospheric composition, escape velocity, and water vapor detection.

Dataset Used: NasaExoplanetArchive from astroquery.ipac.nexsci.nasa_exoplanet_archive

The first part of this project assesses and visualizes the potential habitability of confirmed exoplanets. Using parameters such as equilibrium temperature, planet radius, and stellar characteristics, I compute incident stellar flux and classifies planets based on whether they fall within a simplified habitable zone (HZ).

A scatter plot of equilibrium temperature versus planet radius, with points colored to indicate whether the planet is in the simplified HZ (based on stellar flux: 0.35–1.75 Earth units). Earth’s radius is also marked as a reference.

A refined scatter plot focuses on planets with radius ≤ 100 Earth radii and applies custom habitability classifications:

Potentially Habitable: 0.5 ≤ radius ≤ 2.5 Earth radii and 180 K ≤ temperature ≤ 310 K.

Too Cold/Small, Too Hot/Large, and Unclassified for planets outside those bounds.

A planet’s ability to retain its atmosphere depends largely on the balance between escape velocity and incident stellar flux. High escape velocity (usually associated with larger, more massive planets) helps retain lighter gases like hydrogen. However, intense stellar flux, especially at low escape velocities, can strip away atmospheres. Therefore, as the plot shows, planets with high stellar irradiation and low escape velocities are less likely to retain H-rich envelopes - a critical factor for atmospheric evolution and composition.

The following plot elaborates on which types of planets actually retain hydrogen-rich atmospheres. The distribution shows that larger planets retain H-rich envelopes (red), while smaller planets lose them (blue). Orbital distance also plays a role, though not as strongly as radius and escape velocity. In summary, I found that most small planets are hydrogen-poor, even if they're not extremely close to their star.

Incident stellar flux vs. planetary escape velocity, color-coded by the fraction of hydrogen-rich (H-rich) envelope.

Planet radius as a function of orbital distance, color-coded by the fraction of hydrogen-rich (H-rich) envelope.

A planet’s ability to retain its atmosphere depends largely on the balance between escape velocity and incident stellar flux. High escape velocity (usually associated with larger, more massive planets) helps retain lighter gases like hydrogen. However, intense stellar flux, especially at low escape velocities, can strip away atmospheres. Therefore, as the plot shows, planets with high stellar irradiation and low escape velocities are less likely to retain H-rich envelopes - a critical factor for atmospheric evolution and composition.

The following plot elaborates on which types of planets actually retain hydrogen-rich atmospheres. The distribution shows that larger planets retain H-rich envelopes (red), while smaller planets lose them (blue). Orbital distance also plays a role, though not as strongly as radius and escape velocity. In summary, I found that most small planets are hydrogen-poor, even if they're not extremely close to their star.

Stellar luminosity vs. orbital distance, highlighting planets with detected water vapor (blue) and those without (red).

One key to exoplanet demographic sorting for Astrobiology is water vapor detection. I found that water vapor detections (blue) occur at intermediate distances and luminosities - likely regions where atmospheres are warm enough for vapor but not so hot that they're stripped or fully dissociated. Water vapor is more likely to survive - or be detectable - in planets that lie within temperate zones around their stars.

Something else I found interesting in this result is that the water vapor detections do not all concentrate in one region of the plot. This may also be biased from the sample I gathered of water vapor detections in atmospheres of exoplanets - meaning not all of the red dots may be accurate as some may be blue.

Distribution of stellar flux for planets with and without detected water vapor in their atmospheres.

Lastly, I created violin plots that show that planets with detected water vapor (right) cluster at moderate flux values. Those with no detections are spread more widely. However, this also demonstrates the extreme difference in sample size (the red sample uses a "jitter" trait to demonstrate otherwise overlapping dots). Undoubtedly, this sample size difference certainly plays a role in any conclusions I could possibly draw from this data.