[1] Most of the exoplanets currently known were discovered using indirect techniques — such as
radial velocity variations of the host star, or the dip in brightness of the star caused by a transiting exoplanet.
Not exact matches
The planet was found with the
radial velocity method, a planet - hunting technique that relies upon slight
variations in the
velocity of a star to determine the gravitational pull exerted by nearby planets that are too faint to observe directly with a telescope.
The
radial -
velocity variations indicate a highly eccentric orbit with a period
of 153.9 days.
Due to the close binary orbital interactions
of the host star with Alpha Centauri A and Star B's own increased stellar activity during recent years, the astronomers were only able to detect the
radial -
velocity variations of host star B that were caused by the 3.236 - day orbit
of the planet (with a semi-major axis
of 0.04 AU) only after more than four and a half years
of careful observation.
I. Performances
of radial velocity measurements, first analyses
of variations.
On March 25, 2015, a team
of astronomers using the Hubble Space Telescope revealed observations which indicate via the transit method that Alpha Centauri B may have a second planet «c» in a hot inner orbit, just outside planet candidate «b.» After observing Alpha Centauri B in 2013 and 2014 for a total
of 40 hours, the team failed to detect any transits involving planet b (previously detected using the
radial velocity variations method and recently determined not to be observed edge - on in a transit orbit around Star B).
Due to the close binary orbital interactions
of the host star with Alpha Centauri A and Star B's own increased stellar activity during recent years, the astronomers were only able to detect the
radial -
velocity variations of host star B that were caused by the 3.236 - day orbit
of the planet (with a semi-major axis
of 0.04 AU) only after more than three years
of careful observation.
Prior to 2009, small but significant
variations in
radial velocity had been detected which may have been caused by a substellar companion
of one to nine Jupiter - masses with an orbital period
of 50 years
of less (Campbell et al, 1988, pages 904, 906, and 919).
The transit signals were detected in photometric data from the Kepler satellite, and were confirmed to arise from planets using a combination
of large transit - timing
variations,
radial -
velocity variations, Warm - Spitzer observations, and statistical analysis
of false - positive probabilities.
As a subgiant star subject to pulsations which affect careful measurements
of variations in
radial velocity caused by the gravitational pull
of substellar companions, astronomers would find it very difficult to detect any Earth - type planet around Beta Hydri using present methods.
Kepler - 19 joins the small number
of systems that reconcile transit timing
variation and
radial velocity measurements.
Kepler 18 - b, c, and d: A System
Of Three Planets Confirmed by Transit Timing
Variations, Lightcurve Validation, Spitzer Photometry and
Radial Velocity Measurements
Radial velocity observations from observing runs in 2000 and 2004 reveal a periodic
variation of 3.30 ± 0.02 d, which is consistent with the previously determined value
of 3.3125 ± 0.0002 d.
If you are new to this saga make sure you read Tau II Abstract: The successful detection is reported
of radial -
velocity variations due to orbital motion
of the substellar companion
of the star tau Boötis, from data obtained with a small aperture (0.4 - m) telescope and a fibre - fed high resolution spectrograph.
The primary shows long - period
radial velocity variations that indicate the presence
of a low mass companion whose projected mass is in the planetary regime (m sin i = 9.33 Mjup).
However, the high luminosity
of the primary star, intense Ca II H and K emission (Smith and Dominy, 1979), and
radial velocity variations somewhat larger than can be accounted for by the expected uncertainties suggested that Delta Eridani might be an RS CVn - type binary and therefore a photometric variable like most members
of that class.
Analysis
of radial velocity variations suggest that this probable red dwarf star has about 15 percent
of Sol's mass (Irwin et al, 1992).
As CORVAL monitoring failed to detect significant
radial velocity variations over period
of 3,400 days — or over 9.3 years (Duquennoy and Mayor, 1991, pp. 492 and 506), the detection is now considered to be spurious.
High - precision
radial -
velocity measurements confirm a sinusoidal
variation with the period and phase predicted by the photometry, and rule out the presence
of line - bisector
variations that would indicate that the spectroscopic orbit is spurious.
We also find a slow
variation in the
radial velocity of Procyon, with good agreement between different telescopes.
Scientists were also able use the infrared spectroscopy to look at
radial velocity variations (an analysis
of the light spectrum) to determine that water was present.