Cool Worlds Podcast #28 Néstor Espinoza - JWST, Exoplanet Atmospheres, Molecule Detection
Dec 5, 2025
Néstor Espinoza, an associate astronomer and mission scientist at the Space Telescope Science Institute, dives into the fascinating world of exoplanet atmospheres. He shares insights on various techniques like transmission spectroscopy and secondary eclipses for probing atmospheric composition. Néstor contrasts findings from JWST with earlier Hubble observations, highlighting unexpected discoveries such as CO2. He discusses the challenges of detecting thermal signatures and how JWST's instruments help unravel the mysteries of distant worlds, all while reflecting on the societal value of exoplanet science.
AI Snips
Chapters
Transcript
Episode notes
Use Phase Curves To Break Degeneracies
- Use phase curves to measure day–night contrasts without precise secondary-eclipse timing.
- Phase curves break degeneracies and distinguish bare rocks from atmospheric heat redistribution.
Choose Instruments By Wavelength And Brightness
- Each JWST instrument has strengths: NIRISS/NIRSpec/NIRCam for 0.6–5 microns, MIRI for >5 microns.
- NIRSpec prism gives broad 0.6–5 μm coverage in one shot but saturates on bright stars.
Stars Contaminate Even Mid‑IR Observations
- Stellar activity affects spectra well into the mid-infrared, contrary to pre-launch expectations.
- Heterogeneities and flares can distort JWST transit/emission signals even at 15 microns.