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[006]·aug_2026final

Exoplanet Transit

Kepler photometry pipeline that detects, characterizes, and stress-tests a real exoplanet transit signal — built with a 7-person team for Astron 9 (Introduction to Python for Astrophysics).

  • Astrophysics
  • Python · lightkurve
  • Signal Processing
  • Kepler Photometry
Writeup ↗
exoplanet_transit — kic6922244.datKIC 6922244
3.52 dPOWER ≈570depth 0.45%01 bls_peak · period 3.52 d, power ≈57002 transit_dip · depth 0.45%, Rp ≈0.115 R☉03 habitable_zone0.048 AUhabitable zoneAU 0AU 2.68× closer than Mercury · equilibrium temp 1661.7 K · not habitableTARGET KIC 6922244 · MISSION KEPLER · METHOD TRANSIT (BLS)
TargetKepler-8b · KIC 6922244
Period3.52 d · BLS power ≈570
Transit depth0.45% · Rp ≈ 0.115 R☉
Habitability1661.7 K · not habitable

Pipeline Breakdown

4 stages
B.01

Data Cleaning & Detrending

Pulled Kepler photometry with lightkurve, stripped NaNs and 5σ outliers, normalized flux, then flattened the curve to remove stellar rotation and starspot drift while preserving the short transit dips.

lightkurve · remove_outliers · flatten()
B.02

Transit Detection (BLS)

A Box Least Squares periodogram returned a dominant peak at 3.52 days, power ≈570 against a ≈10–50 noise floor. Phase-folding at that period produced a clean, repeating box-shaped dip — not a one-off event.

BLS periodogram · phase fold
B.03

Radius & Companion Check

Transit depth gives planet radius via Rp = R*√δ: 0.115 solar radii against Kepler-8b’s published 0.146 (21% error, mostly limb darkening). A scipy N-body simulator then tested transit-timing variations for signs of a hidden second planet.

scipy.curve_fit · solve_ivp N-body
B.04

Habitability

Kepler’s third law places the planet 0.0483 AU out — 8× closer than Mercury — with an equilibrium temperature of 1661.7 K. The computed habitable zone spans 1.642–2.365 AU, well outside the planet’s orbit.

Kepler's 3rd law · equilibrium temp

Process

6 phases
  1. P1Method SelectionCompared transit, radial velocity, direct imaging, and microlensing; chose transit for reliability and open data.
  2. P2Data AcquisitionPulled Kepler photometry for KIC 6922244 (Kepler-8) with lightkurve.
  3. P3Cleaning & DetrendingRemoved NaNs/outliers, normalized flux, flattened long-term stellar variability.
  4. P4Period SearchRan a BLS periodogram, found the dominant 3.52-day peak, phase-folded the light curve.
  5. P5Physical CharacterizationDerived planet radius, semi-major axis, equilibrium temperature, and habitable-zone boundaries.
  6. P6Companion CheckBuilt a scipy N-body simulator to test whether timing variations hinted at a hidden second planet.
exoplanet_transit / case_studyAstron 9 · Intro to Python for Astrophysics