A star
tugged by an orbiting planet will wobble slightly, which can be detected as a regular shift in the star's color corresponding to the time the planet requires to complete an orbit.
The other is the regular but minuscule variation in a star's radial velocity — its speed through the galaxy relative to Earth's speed — which indicates that the star is being
tugged by an orbiting planet's gravity.
That wiggle would be due to a gravitational
tug by the orbiting planet.
Not exact matches
The two main methods — measuring the wobble of stars caused
by the gravitational
tug of an
orbiting planet and measuring the periodic dimming of a star as a
planet passes in front — both favor big
planets in close
orbits.
These telescopes rely on detecting any Doppler shifting of the parent star caused
by an
orbiting planet tugging it this way and that, but this method is vulnerable to interference from eruptions on the star's surface and other distractions.
The two methods of detecting extrasolar
planets, nicknamed «wobble and blink,» involve plotting tiny shifts in a star's motion caused
by the gravitational
tug of its
orbiting planets, and catching the slight dimming in a star's light that occurs whenever a
planet passes between the star and an observer's telescope.
They then calculated the size, position and mass of K2 - 229b
by measuring the radial velocity of the star, and finding out how much the starlight «wobbles» during
orbit, due to the gravitational
tug from the
planet, which changes depending on the
planet's size.
For this, TESS is relying on follow - up studies
by ground - based telescopes, which can watch for tiny periodic Doppler shifts in the frequency of a star's light caused
by an
orbiting planet tugging on it.
In October, Xavier Dumusque at the Observatory of Geneva and colleagues described a slight wobble in Alpha Centauri B, caused
by the
tug of an Earth - mass
planet orbiting every three days around that yellowish, sunlike star.
The
planet was found using the radial velocity method: Telescopes scrutinize a star's light to see if its frequency is periodically stretched and squeezed
by the Doppler effect as the star is
tugged, first away and then toward us,
by an
orbiting planet.
Astronomers have identified more than 100
planets orbiting stars outside our solar system, primarily
by monitoring the way a
planet's gravity
tugs its star back and forth.
A larger sixth
planet, closer in mass to Saturn, also appears significantly in the data at a greater distance from HD 10180, but the study's authors note that the signal could be caused
by a long - term magnetic cycle on the star rather than the
tug of an
orbiting planet.
The new discoveries were made with the help of the radial velocity method, which looks for the periodic shifts of certain spectral lines in a star's light that are caused
by the gravitational
tug of invisible
planets which
orbit the star.
The discovery caps an 11 - year effort to tease out information from instruments on ground - based telescopes that measure minute variations in starlight caused
by the gravitational
tugs of
orbiting planets.
Twenty - two of 166 nearby stars, selected at random, had a total of 33
planets, data teased out
by breaking down the starlight to look for tiny aberrations caused
by the gravitational
tugging of the
orbiting brood.
«We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated
by the gravitational
tugs from Earth - sized
orbiting planets,» study coauthor Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz, said in a statement.
The changes in eccentricity of Earth's
orbit are due to alterations in the gravitational
tugs induced
by other
planets.