Three detection methods are exoplanet transit photometry, the radial-velocity method, and exoplanet direct imaging. Transits detect obscuration of the star; radial velocities detect stellar reflex motion; imaging separates the planet's own reflected or thermal light from the star.
Exoplanet transit photometry supports wavelength-dependent exoplanet transmission spectra, while the same orbital geometry supports exoplanet secondary eclipses and phase-resolved planetary spectra. Exoplanet direct imaging provides resolved light for atmospheric spectroscopy. Stellar radial-velocity discovery alone does not measure an atmosphere, although high-resolution follow-up can separate a moving planetary molecular spectrum through its changing Doppler effect.
- Resolvable projected separation: the angular separation is , so a wide orbit around a nearby star places the planet beyond the instrument's inner working angle, related to and the coronagraph design.
- Sufficient planet-star contrast: young, massive planets remain intrinsically hot and bright in the infrared, improving contrast against the star; starlight suppression and favorable observing wavelengths further help.
A wide orbit improves separation but weakens reflected-light illumination and lengthens the orbital period. These conditions therefore describe imaging sensitivity, not an assertion that every detection method becomes easier at large separation.
Articles by others on the same topic
There are currently no matching articles.