Week 4 - Exoplanets Flashcards
How does the Radial Velocity method work?
Analysis of a star’s spectrum. Passing light through spectrometers. Spreads light into component wavelengths. Examining spectrum can tell which atoms or molecules are present in the outer layers (atmosphere) of a star.
The spectral lines also provide information about the star’s rotation and wobble due to the presence of other objects around it, and whether they are stars or planets.
How does the Transit method (photometry) work?
Measures drops in starlight caused by those planets whose orbits are oriented in space such that they periodically pass between their stars and the telescope; transit observations reveal the sizes of planets as well as their orbital periods
What are the disadvantages of the transit method?
In order for the photometric effect to be measured, a transit must occur. Not all planets orbiting other stars transit their stars as seen from Earth; a distant planet must pass directly between its star and Earth.
What are the disadvantages of radial velocity method?
Not possible to observe hundreds or even thousands of stars simultaneously with a single telescope – as is done with Transit Photometry.
Can produces false signals, especially in multi-planet and multi-star systems.
What are the advantages of radial velocity method?
Allows for the eccentricity of the planet’s orbit to be measured directly.
Radial velocity of a star can only yield estimates a planet’s minimum mass, distinguishing the planet’s own spectral lines from those of the the star can yield measurements of the planet’s radial velocity.
This allows astronomers to determine the inclination of the planet’s orbit, which enables the measurement of the planet’s actual mass
What are the advantages of transit method?
Can provide accurate constraints on the size of detected planets.
When combined with the Radial Velocity method (which can determine the planet’s mass) one can determine the density of the planet. From this, astronomers are able to assess a planet’s physical structure and composition.
