Exoplanets

Question 1

Define the habitable zone

Answer 1

Distance from the star so that these planets have liquid water on the surface

Question 2

Why are exoplanets difficult to find?

Answer 2

•very faint as intrinsically and relative to their parent star
•very close to their parent star

Question 3

What is the closest star to the sun?

Answer 3

Proxima Centauri a red dwarf

Question 4

What is our closest planet?

Answer 4

Proxima Centauri b

Question 5

Describe Proxima Centauri b

Answer 5

•orbits with habitable zone
•might be tidally locked
•star has solar flares which can increase luminosity by factor of 10000
•4.2 light years from earth

Question 6

What does the amount of Doppler shift depend on?

Answer 6

Inclination of orbit

Question 7

What are eccentricities?

Answer 7

Deviations from sinusodial light curve indicate elliptical orbits

Question 8

How do transits detect exoplanets?

Answer 8

If a planet moves between us and its parent stars it will block some starlight. With this method we can detect planets which orbit directly in front of the star.

Question 9

How many planets have been discovered through transit method?

Answer 9

7

Question 10

Describe planet J1407b

Answer 10

•super Saturn
•orbits brown dwarf j1407
•200 times larger than Saturns rings
•detected through transit method

Question 11

Describe kepler 16b

Answer 11

•Saturn-mass planet orbiting binary star
•transits of both stars been observed
•Whitburn habitable zone but gas giant

Question 12

What is gravitational lensing?

Answer 12

Light bending around a massive object causing us to see multiple images of a single real object

Question 13

What can cause anomalies in light curves?

Answer 13

If lens star has an orbiting planet ( can be used to detect low mass planets)

Question 14

What do objects in multi planet system orbit?

Answer 14

Their common centre of mass

Question 15

Describe direct imaging

Answer 15

•one use of adaptive optic
•light of star is blocked out
•only possible for planets with large orbits

Question 16

How many exoplanets have been detected?

Answer 16

Over 5000

Question 17

What do extrasolar planets often have?

Answer 17

Eccentric orbits

Question 18

What are hot jupiters?

Answer 18

Exo planets that have masses and radii similar to Jupiter but periods of few days

Question 19

Why have we discovered so many hot Jupiters?

Answer 19

Strong selection effect, since such planets easier to find for most detection methods

Question 20

How do hot Jupiters differ from our solar system?

Answer 20

•cannot form in situ and within frost line so unable to build from ices
•possibly formed further out and migrate inwards

Question 21

What type of planets require long monitoring to seee orbits?

Answer 21

Earth like planets

Question 22

How many planets did the Kepler space telescope detect?

Answer 22

Over 2500 planets through transit technique

Question 23

What is good evidence for the disk formation model of planets?

Answer 23

Kepler detecting number of multiple planet systems that tells us that orbital planes of planets must be very. Loosely aligned or wouldn’t all transit

Question 24

Describe transmission spectroscopy

Answer 24

•planet appears larger within an absorption line
•atmosphere helps to absorb light of star
•outside absorption feature the light can go through the atmosphere

Question 25

What do spectral lines do to appearance of planets?

Answer 25

Make them look bigger

Question 26

What is the main purpose of the TESS mission?

Answer 26

To find close by planets for characterisation via transit method

Question 27

Describe pulsar planets

Answer 27

•most likely formed from debris of explosion
•unlikely life is possible due to very high radiation

Question 28

Why did no one expect pulsars to have planets?

Answer 28

Pulsars result of supernovae explosions