!xoplanet"#e o$er worlds of $e cosmo"

%aseous giants - super-Ear$"!ar$ twins ? Life?

Stéphane UdryGeneva University

In 1995, a breakthrough:the first planet around another Sun

A Swiss team from the Geneva Universtity discovers a planet – 51 Pegasi b – 48 light years from Earth.

Artist's concept of an extrasolar planet (Greg Bacon, STScI)7

Michel Mayor & Didier Queloz

8

Temporal evolution of the discoveries

!"#$%&#'

()*)+,-'

NeptunesSuper-Earths

Jupiter

Earth

Towards lower masses

First 10 years Now Now Future

!x&a-solar Planet"

Why?

How?

What are we finding?

What next?

2

Five planets were known from the ancients who saw them move on the night sky

Mercury, Venus, Mars, Jupiter and Saturn were the “wandering stars” (from the greek “!"#$%&'(”)

Epicurius (341 - 270 AC)

Letters to Hérodotus

Plurality of distant worlds? Thousands of years ago, Greek philosophers speculated...

“There are infinite worlds both like and unlike this world of ours...We must believe that in all worlds there are living creatures and planets and other things we see in this world.”

And so did medieval scholars.... at the cost of their lives

The year 1584

"There are countless suns and countless earths all rotating around their suns in exactly the same way

as the seven planets of our system. We see only the suns because they are the largest bodies and are luminous, but their planets remain invisible to us because they are smaller and non-luminous. The countless worlds in the universe are no worse and no less inhabited

than our Earth.”

Giordano Bruno

in De L'infinito Universo E Mondi

4

The Solar System

'()ar and planetary forma*o+ Collapse of a gas cloud

Discs : natural by-product of

stellar formation

=> nursery of planets

Hubble space telescope

Stellar & planetary formation zone

Protostellar discsMolecular hydrogen clouds

Star forming regions

Older stars:debris disks

15

Planets buid up from the gas and dust particles in

the protoplanetary discs

Evaporation of the gas in the inner regions

=> solid planets

Further out, accretion of gas on the previously formed solid cores

Solar System Planets

How many planets? How many stars?

Billions

of

stars…

If every star had a planet?

Planets are common

bodies in the universe

Billions of stars=> Billions of planets

Deep Universe

Endless number of galaxies

How to detect those planets

Stars are a billion times brighter…

…than the planet

…hidden in the glare

Like this firefly.

Detection methods: 2 body motion property

,ndirect de(c*on me$od: measure of star veloci-

Principle:

Measurement of the Doppler shift

Period:

star-planet separation

Amplitude:

component masses

Precision: 3-10 m/s - Jupiter-Sun : 12 m/s

Radial velocities - Saturne-Sun : 3 m/s - Earth-Sun : 9 cm/s

The 1st planet: 51 Pegasis Observatoire deHaute-Provence

Telescope:193 cm

Mpl = 0.5 MJup

P = 4.2 joursa = 0.04 UA

31

Light pollution

Mont Wilson observatory in Californie

La Silla, Chile

Swiss in the southern hemisphereEuler+Coralie – La Silla (Chile - ESO site)

~ 55 planets

Keck (1997-….)

.ensus of RV programme"

Lick (1992-…)

Elodie (1994-2006)

-> Sophie (2006-...)

HARPS (2003-...)

Coralie (1998-...)

>4000 stars

>400 planets

Others - Tautenburg - Texas/HET - Japan - Canary Islands - etc

AAT (1998-...)

Extra-solar planets1995-2009: >~400 planets

Statistical properties

– Percentage

~7% of observed stars

~1% of Hot Jupiters

– Mass distribution

0.016 MJup < Mpl < 20 MJup

– Period

1.2 d < P < …

– Mass-period distribution

– Eccentricity-period distribution

0 < e < 0.93

– Proprerties of host stars

metallicity, mass, binarity

F G K M

Pegase 51 b

Surprise !!!

Prototype of “Hot Jupiters”

Formation?

Lynette Cook

Migration -> centre Need to stop !!!

G. Bryden

/arious 0pes of sys(m"

A large diversity!

Soleil

55 Cnc

~200 exoplanets discovered, but ....

mainly “Jupiters”

Where are the small planets?

After 10 years...

The planets discovered so far are closer in mass to Jupiter.

Jupiter’s diameter is eleven times greater than the Earth’s, and it has over 300 times the mass.

This is what we are looking for

This is what we’ve found

1ARPS: stability at 1 m/s

Pressure controlled Temperature controlled

- Observatoire de Genève- Physikalisches Institut, Bern- Observatoire Haute-Provence- Service d’Aéronomie, Paris- ESO

Very stable

Very precise

HARPS : The swiss precision

1igh-precision -> zoom 2ward lower-mass planet"

p = 9.5 d mpl = 10.5 MEarth

HD 69830: un trio de Neptunes

P1 = 8.67 j a = 0.078 AU M sini = 10.2 MTerre

P2 = 31.6 j a = 0.186 AU M sini = 11.8 MTerre

P3 = 197. j a = 0.63 AU M sini = 18.1 MTerre

Lovis et al., Nature 2006

HARPS@3.6-m telescope, ESO La Silla

P1 = 4.31 jours

m1 sini = 4.3 M!

P2 = 9.62 jours

m2 sini = 6.9 M!

P3 = 20.5 jours

m3 sini = 9.7 M!

A 3 super-Earth system

Two super-Earth (5-7 MEarth) in a 4-planet system+ a very light planet of 1.94 MEarth

P1=3.15d M1=1.94MEarth

P2=5.37d M2=15.7MEarth

P3=12.9 d M3=5.4MEarth

P4= 66.8 d M4= 7.1 MEarth

Gl 581, M3V star

6 M. Mayor et al.: A Earth-type planet in GJ 581 planetary system

P = 66.8 day ; m sin i = 7.1M!

!5

0

5

RV4

[ms"

1]

RV4

[ms"

1]

0 0.25 0.5 0.75 1!!

P = 12.9 day ; m sin i = 5.4M!

!5

0

5

RV3

[ms"

1]

RV3

[ms"

1]

P = 5.37 day ; m sin i = 15.7M!

!20

!10

0

10

20

RV2

[ms"

1]

RV2

[ms"

1]

P = 3.15 day ; m sin i = 1.94M!

!5

0

5

RV1

[ms"

1]

RV1

[ms"

1]

!10

!5

0

5

10

O!

C[m

s"1]

O!

C[m

s"1]

53000 53500 54000 54500 55000

Julian date !2,400,000.0 [day]Julian date !2,400,000.0 [day]

Fig. 2. Radial velocity curves for planets e, b, c and d from top to bot-tom. The residual velocities to the four planets keplerian fit are plottedon the lowest panel.

0.5

0.75

1

1.25

Ca

IIH

+K

Ca

IIH

+K

3000 3500 4000 4500 5000

Barycentric Julian Date - 2450000.0 [day]Barycentric Julian Date - 2450000.0 [day]

0

0.25

0.5

Pow

erPow

er

100 101 102 103 104

Period [day]Period [day]

Fig. 3. The Ca !!H+K index as function of the Julian dates (upper panel)and its periodogram (lower panel).

observational bias to detect these low mass companions, wecan see a rise of the distribution towards super-Earth planets(cf. Fig. 7 of the above mentionned reference).

! The majority of systems having planets with masses in therange of super-Earths and Neptunes are multiplanetary sys-tems. Among the 6 planetary systems having a detectedsuper-Earth, (GJ 876, HD 40307, HD 7924, GJ 176, GJ 581,HD 181433) two-third are multiplanetary systems. Thesesystems are of di!erent types : 2 systems with one super-Earth plus one or two gaseous giant planets (GJ 876, HD181433), 2 systems with several planets on non resonant or-bits (HD 40307, GJ 581) and two systems with only one de-tected planet (GJ 176, HD 7924). However we cannot ex-clude that other planets could be detected in the future inone of these two systems. Some hints of additional planetsare observed in the periodogram of HD 7924 (Howard et al.2009).

! Low mass planetary systems seem not to be more frequentaround metal-rich host stars (Udry et al. 2006).

! Based on a preliminary analysis of the radial velocity mea-surements of the 200 solar-type stars of our HARPS highprecision survey, we have detected low mass close-in plan-ets (P< 50d and m sin i < 30M") around 30% of these stars(Lovis et al. 2009).

Multiplanetary systems with several low mass close-in plan-ets are interesting as providing constraints for models of plane-tary formation. We can specially emphazise the three systems :HD 69830 (3 planets), HD 40307 (3 planets) and GJ 581 (4 plan-ets).

Terquem & Papaloizou (2007) have studied the migrationof cores and terrestrial planets induced by their interaction withthe protoplanetary disk. “Their results indicate that if hot super-Earths or Neptunes form by mergers of inwardly migratingcores, then such planets are most likely not isolated. We wouldexpect to always find at least one, more likely a few, companionson close and often near-commensurable orbits”. The high per-centage of multiplicity observed in the above-mentionned sys-tems has to be noted in comparison with that model. Howeverwe can also remark that observed periods are always quite far tobe near-commensurable.

Observable consequences of planet formation models in sys-tems with close-in terrestrial planets have been addressed by

'ys(ms wi$ Neptunes and super-Ear$"3n emerging new popula*o+

Properties?

comparison with giant panets?

=> 30% solar-0pe stars hos4 56olid7 planet"

19

Goal “The Pale Blue Dot”The race is on...

…on the ground and in space.

Keck Interferometer

Spitzer Space Telescope

SIM PlanetQuest

KeplerLarge Binocular Telescope Interferometer

Terrestrial Planet Finders (NASA)/ Darwn (ESA)

Spitzer: IR procheobservation de gaz “froid”formation stellaire et planétaire

Herschel: mid-IRLancement: 14 mai 2009, 15h09Plus grand télescope en vol

James-Webb Space Telescopes (2013)D=6.5m

Observatoire européen de Paranal (Very Large Telescope, Chili)

'PHERE

En cours de développementInstallation sur le ciel: 2011

Spectro-Polarimetric High-contrast

Exoplanet REsearch

Un “appareil photo” pour le VLT

TMT (USA)Thirty Meter Telescope

492 x 1.4m = 30m

The giants of the future

GMT (Canada-USA)Giant Mirror Telescope

7 x 8.4m = 25m

European-Extremely Large Telescopes984 x 1.45m = 42m

58

The power of giant telescopes: resolution and collecting area

2

Are we alone ?

8e(c*on of $e 5Pale Blue Dot7Search for biotracers on planets

twins of the Earth

Need existence of liquid water

Many of the new planets get too hot or too cold to support life.

Too hot! Too cold!Just right!

Habitable Zone

y

Earth

semi-major axis

of th

e st

ar

(Franck Selsis, priv comm)

Super-Earths…

1 M!

1 R!

8 M!

1.75 R!

65

Signs Of Life On An Earth-like Planet

Vegetation

Plantproduct

Plant life

Bacteria

observed

Water

Oxygen

Carbondioxide

Methane Nitrousoxide

Ozone

Needed for life Primordial;

& bacteria product

8e(c*on of $e 5Pale Blue Dot7Search for biotracers on planets

twins of the Earth

68

LIFE

LIFE

Hypertelescopes

A fleet of small telescope collectors working as a dilutated giant mirror.

Resolution = big telescope one

Possible base > 150 km

Antoine Labeyrie

collectors

Hypertelescopes

Images of planetscontinentsvegetation

Giordano Bruno1548-1600

“Un univers infini et une infinité de Mondes"

Epicure 341 - 270 AC Lettres à Hérodote

“There are infinite worlds both like and unlike this world of ours...We must believe that in all worlds there are living creatures and planets and other things we see in this world.”

To improve life here, To extend life to there,To find life beyond.

We shall not cease from exploration And the end of all our exploring Will be to arrive where we started And know the place for the first time.

! T.S. Eliot Four Quartets

26

One day maybe....

we might turn again to poets, artists and philosophers….

to better understand ourselves.