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.