Exoplanets

Question 1

What is an exoplanet?

Answer 1

A planet that does not orbit the sun

Question 2

What is KEPLER and what was its job in terms of exoplanets?

Answer 2

KEPLER is a NASA space telescope launched in March 2006. Its job was to do a transit search with 150000 stars over 3.5 years. So far (3.3.15) 1019 confirmed and many more potential candidate.

Question 3

What astronomers measure on exoplanets and how does this affect our knowledge if understanding them?

Answer 3

TTV (Transit Time Variations) - measuring the orbital time. This is not perfect due to tidal working e.g. KO1-142 c - confirmed after by radial velocity
Mass Vs. Radius - understand composition

Question 4

What does the future hold for missions into space regarding exoplanets?

Answer 4

Space based telescopes (from discovery to characterisation)
VLT - ground telescope to counter atmospheric turbulence
CHEORS - more detail into KNOWN exoplanets giving more accurate characteristics
TSS - whole sky survey - find candidates for later mission

Question 5

Discovery so far (bias affect)?

Answer 5

We are discovering large planets (Jupiter size)

Size of orbits mostly close to the star - bias effect due to transit (easy to find and identify multiple planets)

Question 6

What types of methods are used to detect an exoplanet?

Answer 6

Radial velocity (watching for wobble) - orbiting planets cause stars to wobble in space changing colour (spectroscopy) of the light astronomers observe. Dopler shift good for heavy planets in tight orbit e.g. 51 pegasus B 
Direct imaging - astronomers can take pictures of exoplanets by removing overwhelming glare of the stars they orbit as the star brightness is greater than the planets brightness. Good for large distant planets or small cool nearby stars e.g. Epsillon Erendi in the Kuiper Belt
Gravitational lensing (Microlensing) - light from a distant star is bent and focussed by gravity as a body (planet or star) passes between the star and the earth
Transits - when a planet passes directly between its star and observer it dims the star by a measurable amount. Light from a star obscured by a planet