Sarah, Ellie, Adan and Sruthy
The Transit Method
• The main disadvantage of the transit method is that for us to
detect a planet, the orbit must be precisely aligned with our
point of view.
OurProject
TrES-3b
Jupiter compared to TrES-3b
Mass
1.199±0.052 MJ
Orbital Period
2.4706 ± 0.00001 d
Radius
1.341 ± 0.081 RJ
Surface gravity
3.284±0.016 g
Temperature
-
Distance
750±30 ly
Type
Gas Giant
Star
GSC 03549-02811
Constellation
Draco
Duration of
transit
0.042days
Dip in brightness 0.025
Ratio of planet
to star radius
0.16
Theory
•Radius, mass of star, as well as planet’s period, estimated through
observation
•Then you can calculate:
1) semi-major axis
2) orbital speed
3) radius
4) transit duration
5) impact parameter
6) Inclination
•
Calculations based on Newton & Kepler’s Laws.
GJ-1214 b
Mass
6.55 ± 0.98 M⊕
Orbital Period
1.5804 ± 1.6x10-7d
Radius
2.678 ± 0.13 R⊕
Surface gravity
0.91 g
Temperature
393–555 K
Distance
42 ly (12 pc)
Type
Super-Earth
Star
GJ 1214
Constellation
Ophiuchus
Duration of
transit
0.039 days
Dip in brightness
0.0144
Ratio of planet to
0.12
star radius
Qatar-1b
Mass
1.09±0.08 MJ
Orbital Period
1.4200 ± 1.6x10-05 days
Radius
1.164 ±0.06 R
Surface gravity
-
Temperature
1380±45 K
Distance
550 ly (169 pc)
Type
Gas Giant
Star
Qatar-1
Constellation
Draco
.
Duration of
transit
0.060 days
Dip in brightness
0.025
Ratio of planet to
0.16
star radius
WASP-2bSP-2b
Jupiter compared to WASP-2b
Mass
0.847 ± 0.045 MJ
Orbital Period
2.1522 ± 4x10-7 days
Radius
1.079 ± 0.033 RJ
Surface gravity
3.279 ± 0.036 g
Temperature
1300 ± 54 K
Distance
470 ly (144 pc)
Type
Gas Giant
Star
WASP-2
Constellation
Delphinus
Duration of
transit
0.060 days
Dip in brightness
0.019
Ratio of planet to
0.14
star radius
Detecting
Exoplanets
Using Radial Velocity or
the Doppler Method
What is radial velocity?
Velocity along the line of sight
toward or away from the observer.
This diagram shows
how an orbiting
planet will change
the position of the
star it orbits due to
its gravitational tug.
What is spectroscopic radial velocity
and how can it be used to determine a
planet’s radial velocity?
S.R.V is the radial
component of the velocity of
the source at emission and
the observer at observation, as
determined by spectroscopy.
Advantages and Disadvantages of
using the radial velocity method.
Advantage:
• The planet's eccentricity
can be measured directly.
Disadvantage:
• Can only estimate a
planet’s minimum mass.
Easier to detect planets orbiting low
mass stars because....
• More affected by the planets’ gravitational tug.
• Generally, the planets rotate more slowly when
orbiting a low mass star.
R.V. Method is the most productive
method used...
456 Exoplanets – 31 confirmed and 323 candidates.
Of the 31 confirmed
Exoplanets – 1 Exoplanet
has been identified as
having the potential for
habitability – Gliese 581-d