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Chapter 10

Astronomy 1021 Chapter Notes - Chapter 10: Planetary Migration, Upsilon Andromedae, Radial Velocity

Course Code
ASTR 1021
Chris Racknor

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Chapter 10: Other Planetary Systems
The Habitable Zone
The right temperature
oNot too hot not too cold
Liquid water on the surface of the planet
A medium for life to live in/ to transport things in
oEx. Blood stream
Big enough size of a rocky planet
Right air pressure
Extrasolar Planet- a planet that is not orbiting the Sun (exoplanet)
When naming them, we place a lowercase letter after the star name
Lettered in term of when they are discovered
o"b" for the first planet found, "c" for the second…
o"a" is reserved for the star itself
Ex. 51 Peg b
Gliese 876 d is closer to the star than Gliese 876 b; distance to the star doesn't
matter with the letter
Direct methods- obtaining an image/spectrum of the planet directly
Indirect methods- establishing the presence of a planet by its effect on the star
Very difficult
oStars are far away, angular separation very small
oPlanets reflect sunlight
But Sun is about a billion times brighter than Jupiter
Planets are much fainter
oMajor glare of starlight interfering
Can work best if:
oThe planet is fairly far away from the star
oStar is close to us
oPlanet is bright compared to the star
oWe can "mask" or reduce the starlight efficiently without reducing the light from the
Need very sharp eyes, but we can do it
Planets emit primarily at infrared; not very hot
oAt infrared wavelengths, a star is "only" a thousand to a million times bright than the
Young planets tend to be hotter, but still looks bad
2M1207 & 2M1207 b
oBrown dwarf- faint type of star, emits very little visible light
oRelatively bright in the infrared
oAlmost a star
oVery far from its star
find more resources at oneclass.com
find more resources at oneclass.com
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