solar system formation 4. outer material accretes to form planetesimals 1. rotating cloud of gas...
TRANSCRIPT
Solar System Formation
4. Outer material accretes to form planetesimals
1. Rotating cloud of gas & dust
2. Cloud spins & flattens, forms a disk
3. Core of disk forms young star
solarnebula
Our Solar System• Types of planets depend on:
- temperature- amount of material
rocky planets(Terrestrial)
gas planets(Jovian)
• Rocky planets formed closer to Sun
• Gas giants formed further out
STANDARD MODEL
ConstellationOrion
Stellar Nurseries
• Example: Orion Nebula
Hubble
• birthplace of new stars, new solar systems?
high eccentricity(more oval)
low eccentricity(more circular)
Vocabulary
• Extra Solar Planet (ESP): a planet around a star other than our Sun
ESP
• brown dwarf: less mass than a star,
more mass than Jupiter
• light year: distance light travels in 1yr
• eccentricity: how elliptical an orbit is
1024 kg
1027 kg
1030 kg
Planet Quest
The First Searches
• 1920s - Edwin Hubble: identified neighboring galaxies• 1980s - B. Smith & R. Terrile: captured 1st image of
debris disk around star
Hubbleoutside galaxy Beta Pictoris
dust disk
Discovery At Last
• 1995: Michel Mayor & Didier Queloz (Swiss) - 1st ESP orbiting star 51 Pegasus
• 1995: Geoff Marcy & Paul Butler (SF State, UC Berkeley) - confirmed discovery - found many more
• 2000’s: dozens more
• by 2006: 193 planets 14 multiple planet systems
and many more now…
Mayor & Marcy
51 Peg
ESP & 51 Peg
Star GQ Lupi & planet
planetGQ Lupi
Tau Bootis
16 Cygni B
55 Cancri
47 Ursae Majoris
70 Virginis
Extra Solar Planets
Distance from parent star (AU)MJUP = mass of Jupiter
1 2
Stars
Characteristics of ESPs
• Jupiter-sized and bigger
• Orbit close to star (closer than Mercury)“Hot Jupiters”
Eccentric orbits Orbit close to star
• Orbits highly eccentric
Detection
• Obstacles - Too far away - Don’t produce any of own light - Lost in glare of parent star
• Solution: look for effects on parent star
Methods of Detection
• Doppler Shift
Doppler Shift
• plus others……
Transit Method
• Transit Method
Direct Detection
• Direct Detection
Doppler Shift & Orbit Wobble
• Star and planet orbit
center of mass
• Tug of gravity causes
star to wobble
• Planet has small
gravitational affect on star
X
X
X = center of mass
gravity
Review: Light Waves
BIGGER wavelengths
smaller wavelengths
Red ‘Shift’ vs. Blue ‘Shift’
waves appear compressed
light moving toward observerlight moving away from observer
waves appear stretched
observer of star
RED SHIFT BLUE SHIFT
DOPPLER SHIFT
Detection: Doppler Shift
• Planet causes star to wobble in circular orbit
movingtoward
observer
moving away fromobserver
• Light from star is Doppler shifted
Detection: Doppler Shift
Wobbles from Neptune-sized planet orbiting star Gliese 436
Real Star Wobbles
Star movingtoward
Star movingaway
Gliese 436
Detection: Transit Method• planet passes between star and observer
• planet blocks out tiny portion of star’s light
• star’s light appears to dim
Detection: Transit Method• planet passes between star and observer
• planet blocks out tiny portion of star’s light
• star’s light appears to dim
Direct Detection
Giant planet and young brown dwarf
• state-of-art infrared images• detect light 200+ light years away
Future Missions• 2001: Keck Interferometer
• 2011: Space Interferometry Mission (SIM) Planet Quest
• 2014: Terrestrial Planet Finder
Keck Interferometer SIM Planet Quest Terrestrial Planet Finder
- began capturing 1st images of gas giant EPSs
- will detect evidence for earth-sized planets
- will send back 1st pictures of nearby planetary systems
What is your favorite planetary body?
Give one scientific reason why.