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Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star. As of November 2022, about 19.5% of known extrasolar planets ...
While the radial velocity method provides information about a planet's mass, the photometric method can determine the planet's radius. If a planet crosses in front of its parent star's disk, then the observed visual brightness of the star drops by a small amount, depending on the relative sizes of the star and the planet. [6]
Most known extrasolar planet candidates have been discovered using indirect methods and therefore only some of their physical and orbital parameters can be determined. For example, out of the six independent parameters that define an orbit, the radial-velocity method can determine four: semi-major axis , eccentricity , longitude of periastron ...
This is the radial velocity method of detecting exoplanets. [ 5 ] [ 3 ] Using the mass function and the radial velocity of the host star, the minimum mass of an exoplanet can be determined. [ 15 ] [ 16 ] : 9 [ 12 ] [ 17 ] Applying this method on Proxima Centauri , the closest star to the solar system, led to the discovery of Proxima Centauri b ...
Doppler imaging was first used to map chemical peculiarities on the surface of Ap stars.For mapping starspots it was first used by Steven Vogt and Donald Penrod in 1983, when they demonstrated that signatures of starspots were observable in the line profiles of the active binary star HR 1099 (V711 Tau); from this they could derive an image of the stellar surface.
This method enables precise measurements at room temperature because it is insensitive to doppler broadening. Absorption spectroscopy measures the doppler-broadened transition, so the atoms must be cooled to millikelvin temperatures to achieve the same sensitivity as saturated absorption spectroscopy.
The method was first described by Philip Njemanze in 2007, and was referred to as functional transcranial Doppler spectroscopy (fTCDS). [ 25 ] fTCDS examines spectral density estimates of periodic processes induced during mental tasks, and hence offers a much more comprehensive picture of changes related to effects of a given mental stimulus.
The initial state of the system, photon energy, angular momentum and other selection rules can help in determining the nature of the intermediate state. This approach is exploited in resonance-enhanced multiphoton ionization spectroscopy (REMPI). The technique is in wide use in both atomic and molecular spectroscopy.