lichtkurve

Lichtkurve, the German term for light curve, is a graph or time series that shows the brightness of an astronomical object as a function of time. It is typically expressed as flux or magnitude and is produced from photometric measurements by one or more telescopes or detectors.

Constructing a Lichtkurve involves repeatedly measuring an object's brightness, calibrating the data with reference sources, and correcting for factors such as atmospheric extinction, instrumental response, and timekeeping. The result is a time-ordered sequence that may be normalized or detrended to reveal intrinsic variability. The sampling cadence, photometric precision, and data gaps influence the interpretation of the light curve.

Light curves encode a range of physical processes. Periodic variations can indicate pulsating stars or eclipsing binaries, while transient dips or rises may signal events such as exoplanet transits, microlensing, or supernovae. For a planetary transit, the depth of the dip is approximately related to the square of the ratio of the planet radius to the star radius, and the duration and shape constrain orbital geometry. Supernova light curves reveal the energy release and ejecta evolution, whereas microlensing light curves show a characteristic symmetric brightening caused by gravitational lensing.

Applications span time-domain astronomy, including exoplanet discovery, stellar characterization, and transient event studies. Data sources range from ground-based surveys to space missions such as Kepler and TESS, which provide high-precision, long-baseline light curves. Challenges include observational gaps, noise, crowding in crowded fields, and systematic errors, all of which must be addressed to extract reliable physical information. Lichtkurven are fundamental tools for measuring sizes, distances, masses, and evolutionary states of astronomical objects.