Planet

mccme.ru

Planet

Garik Israelian

Institute of Astrophysics of Canary Islands, Spain

European Northern Observatory


La Palma

ORM Observatory

2600 meter a.b.s


La Palma

ORM Observatory

2600 meter a.b.s


La Palma

GTC: 10.4 meter

The largest telescope in the world


Tenerife

Teide Observatory

2590 meter a.s.l.


Tenerife

Teide Observatory

2590 meter a.s.l.


Some planets were known to the ancients who

watched them move against the night sky.

Courtesy NASA’s Navigator Program

2


Mercury, Venus, Mars, Jupiter, and

Saturn were the “Wandering Stars.”

Courtesy NASA’s Navigator Program

Planet” comes from the Greek word for “wanderer.”


And other planets were “discovered.”

Uranus

The year 1781

The first planet “discovered.”

William and Caroline Herschel

Neptune

The year 1846

First observed by Galle and d'Arrest

(based on calculations by Adams

and Le Verrier).

Pluto

The year 1930

Discovered by Clyde Tombaugh

Courtesy NASA’s Navigator Program

5


But what about more 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.”

Epicurius

c. 300 B.C

Courtesy NASA’s Navigator Program


And so did medieval

scholars.

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 . . .

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

Courtesy NASA’s Navigator Program

4


In 1995, a breakthrough:

the first planet around another star.

Michel Mayor and Didier Queloz

A Swiss team discovers a planet – 51 Pegasi –

48 light years from Earth.

Courtesy NASA’s Navigator Program 7

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


Methods to Detect Planets

Spitzer, for the first time,

captured the light from two

known planets orbiting stars

other than our Sun. But so far,

most of the extra-solar

planets are being detected

using INDIRECT methods.

Artist Concept:

NASA’s Spitzer Infrared Telescope


Methods to Detect Planets

There are several complementary methods

for detecting planets orbiting distant stars.

Wobble

Doppler – detecting the star wobbling in the line of sight

due to the planet’s gravitational pull

Astrometry – detecting tiny wobble of stars against

other stars in the background.

Planet Transit – detecting a tiny drop in brightness of

the star as a planet passes in front

Coronograph – blotting out the light of the star so

planets can be “seen”

Transit

Coronograph

Astrometry


Massive Planets Cause Stars to Wobble

• Stars and their planets also move

about the common center of mass.

• Since the mass of a star is so much

greater than the mass of a planet,

the “center of mass” (i.e. “balance

point”) is located close to (but not at

the center) of the parent star.

• This means that stars with planets

in orbit around them are not

stationary. Rather, they move slightly

about this balance point producing a

gravitational wobble!

• The gravitational wobble of the Sun

is dominated by the gravity of the

most massive planet Jupiter.

Star moving toward observer

(positive velocity)

far side

of orbit

Star moving away

near side

of orbit


NASA’s SIM PlanetQuest Mission

Are there terrestrial planets orbiting nearby stars?

NASA’s SIM PlanetQuest

Mission will survey nearby

stars for Earth-size planets by

measuring the wobble of stars

against other stars in the

background.

Artist Conception: NASA’s SIM PlanetQuest

This method of detection is

called astrometry.


Doppler shift to measure the tug of planets on

stars. Here is how it works:

So far, nearly all extrasolar

planets have been

discovered with this

technique

If an unseen

planet tugs the

star back and

forth…

…the light from

the star shifts

slightly to the

red as the star

moves away from

you.

…and slightly to

the blue as it

moves toward

you.

Astronomers can

detect these shifts

by very carefully

observing the

spectra (or colors) of

the stars.

Courtesy NASA’s Navigator Program


Detecting Planets: Transit Method

Kepler

NASA’s Kepler

mission will use

the transit method.

When a planet passes by (or transits) a

star, we can detect a slight decrease in

the amount of light from the star.


: -

(‏‏)‏ •


– : ^

– : -

(‏‏)‏ •

COROT


– : ^

– : -




Kepler


Coronograph: We will block out the bright light

from the star.

Telescopes that block the

light from the central star

can take images of planets

that might be in orbit

around them.

Keck Interferometer

The Keck Interferometer

combines the light of two

10-meter telescopes to take

images of hot Jupiter-size

planets that shine bright in

infrared light.


T eff = 5800 K


24000 lines in the optical spectrum of the Sun. 15 % not yet identified !

T eff = 9900 K


How precise ?

accuracy


First planets and first “problems”

(‏‎1995‎‏)‏ Mayor & Queloz

Strange world:

msin(i)=0.47M Jup

P=4.2 days

Separation=0.05 AU


:

( . &)‏ . ( )


!!!


( . )

.=.

=

=()


:

-


( .

(‏ .


( . )

-

!


:

( .

(‏


-

-

-

-

-.

.


!

!

!!!

Need to revise theories


Look at the statistical properties


Mass distribution (HARPS)


Benz et al. (2009)


M > 0.75 Mjup

M < 0.75 Mjup

Neptunes

:-




( .

(‏ .


.


-



No planets

with short

P and high

Mass!


Eccentricity

Distribution!

Only small

difference

between

binary stars

and planets!


Eccentricity

Distribution!

Mayor et al

2012


...



-


-


Planet frequency and stellar [Fe/H]

(‏‎2001-2005‎‏)‏ Santos, Israelian & Mayor


Is the same

true for

Neptunes?

Sousa et al

2011


Is the same

true for

Neptunes?

Mayor et al

20l2


Is the same

true for

Earths?

Buchhave et al. 2012


Chemical Composition

Primordial

Secondary

Planet formation and stellar

evolution does not modify

stellar surface abundance

pollution

Grav. settling, etc


Giant Planet

(Jupiter)

10M ⊕

.

10 core

(Fe, Ni, Si, Ti..)

H

He


Sun

Planet(s)

accretion

Sun


Fractionation ?

Sun

hot

cold

Refractories: Fe, Mg, Si...

Volatiles: C, N, O, S & Zn

Sun

Terrestrial Planets: Fe, Mg

Si, Ca etc. chondritic matter

Giant Planets: icy cores,

CO 2 H 2 O NH 4 etc.


Smith et al. (2000)

Not confirmed by

Sadakane et al. (2002),

Takeda et al. (2001)

T c (K)

Condensation temperature

Condensation temperature


Ecuvillon et al. (2006)


Chemical abundance ratios of 11 solar twins.

Two fits are shown in two Tc ranges : 0 < T c

(K) < 1200

1200 < T c

(K) < 1800


10 solar analogs


36 solar analogs, 14 with and 14 without planets with

similar stellar parameters and metallicities


36 solar analogs with and without planets with simil stellar

parameters and metallicities (coorected for Galactic trends)


71 single stars

24 planet hosts


Non-solar

Compositions


Chemical abundances of 61 planet-host stars and 270 stars without

planets from HARPS GTO program


Chemical abundances of 61 planet-host stars and 270 stars without planets

from HARPS GTO program


Chemical abundances of 61 planet-host stars and 270 stars without planets

from HARPS GTO program


Chemical abundances of 61 planet-host stars and 270 stars without planets

from HARPS GTO program


Graphite, TiC y

solid Si as SiC

Pyroxene

MgSiO3

Olivine

Mg2SiO4

Mg/Si abundance ratios are larger in planet-host stars than in stars without

known planets, although part of this signature is probably due to chemical

evolution effects since planet-host stars are on average more metal-rich than

single stars.


Light elements Li and Be

Angular momentum exchange:

Momentum locked in planets

Transfered to the star by accreted objects

Tidal effects

MS accretion of planetesimals, ingulfment of

planets

-test

Flare activity (spallation reactions: Li & Be))


T > 2.5 ×10 6 K ⇒ 7 Li is destroyed

T < 2.5 ×10 6 K ⇒ 7 Li is preserved

T > 3.0 ×10 6 K ⇒ Be is destroyed

T < 3.0 ×10 6 K ⇒ Be is preserved €

T > 2.0 ×10 6 K ⇒ 6 Li is destroyed

T < 2.0 ×10 6 K ⇒ 6 Li is preserved

T > 3.5 ×10 6 K ⇒ B is destroyed

T < 3.5 ×10 6 K ⇒ B is preserved

Convective cells

Li



T > 2.5 ×10 6 K


7

Li increases during Galactic evolution:

initial for Pop. I~ (initial for Pop. II)x10

BIG BANG (WMAP)

Travaglio et al. (2001)

7

Li is destroyed during the evolution

of Pop. I stars


CLASSICAL MODELS

i. PMS Li depletion (amount depends

input physics and chemical

composition)

ii.

iii.

No MS Li (and Be) depletion for

solar-mass stars and above (base

of CZ too cool)

Fully convective stars: Li depletion

depends on central T age


Overview of depletion pattern

MS

dep

PMS

dep

Li dip

Li chasm

30-50 Myr

120 Myr

600 Myr

4.5 Gyr

T eff (K)

Dispersion


What we do not understand

" Li dip among F-type stars

" Smaller than predicted PMS depletion for

solar-type stars

" Solar MS Li depletion

" Dispersion in otherwise similar stars in old

open clusters and among field solar analogs.

" Dispersion among K-type stars in young

clusters

Non standard processes


GIRAFFE SURVEY: RESULTS

Randich et al. (2008)

A variety of populations! Each

cluster behaves in a different

way. No apparent relationship

• Hyades

○ Be 32 (6 Gyr, [Fe/H]=-0.3)

with metallicity. Initial

conditions?

• NGC 188

▲M67

log n(Li)

Spanò (2006)

Sun is not representative.

T eff (K)

• Be 32

○ Cr 261 (6 Gyr, [Fe/H]~solar


M67 open cluster


Pasquini et al. 2008


The 8 Gyr old NGC 188 ([Fe/H]~solar)

Randich et al. (2003)


Li distribution in Cr 261 ( 6 Gyr, [Fe/H]

=0.13 )

26 stars with

T eff within 50 K

from solar

log n(Li)


TIMESCALES: USE OF Li AS AGE TRACER

n(Li)

α= -0.68±0.09

Little depletion up to α= 100 -1.63±0.08 Myr, continuous

depletion up to 1 Gyr, then bimodal

fast depletion or no depletion →

□ Sestito & Randich (2005)

● FLAMES sample

‘low’ Li (solar) ≡ old (+peculiar evolution)

‘high’ Li (~10xsolar) only Age lower (yr) limit to age

Teff:5750-6050 K


Summary

Li-rich old stars found in the field and OCs.

Depletion stops at ~1 Gyr for part of the stars. Sun is

not representative

Others (including the Sun) undergo fast 10x larger

depletion. Dispersion does not depend on obvious

cluster parameters.

Depletion must be driven by additional parameters

besides age and mass.

Li vs. Teff patterns do not depend on cluster [Fe/H],

but Li vs. mass do


Is Lithium depleted in stars with exoplanets ?


It is possible, in principle anyway, that the low Li abundances of

the Sun and 16 Cyg B with respect to 16 Cyg A may be related

to the presence of planetary companion. Li abundances of 47

UMa, and HD114762 might further support such a connection

between planets/disks, angular momentum evolution, and

photospheric Li abundance.

King et al. (AJ, 113, 1871, 1997)

16 Cyg B 16 Cyg A

Log Li

Log Li


YES or NO

Gonzalez & Laws (2000)

Ryan (2000)

Israelian et al. (2004)

Takeda & Kawanomoto (2005)

Chen & Zhao (2006)

Luck & Heiter (2006)

Takeda et al. (2007)

Gonzalez (2008)

yes

no

yes

yes

yes

no

yes

yes


YES or NO

Israelian et al. (2009)

Gonzalez (2010)

Takeda et al. (2010)

Baumann et al (2010)

Ghezzi et al. (2010)

Sousa et al. (2010)

Delgado Mena et al. (2011)

yes

yes

yes

no

no

yes

yes


Problems ?

Comparison sample

Precise stellar parameters

Unbiased & homogeneous study

(use the same volume limited sample)

Statistics


Our strategy

Unbiased & homogeneous study

Statisticaly signifacant

No young stars (Age < Hyades)

No subgiants

No peculiar stars

New comparison sample from HARPS (GTO)

RV precision < 1m/sec

Precise stellar parameters (Sousa et al. 2008)

30 K (Teff), 0.03 dex (Fe/H), 0.04 dex (log g)


Planet hosts

Single stars

HARPS GTO sample


Li abundances for 23 planet-host stars and 60 stars without planets

from HARPS GTO program and CORALIE program


Planet host

Single stars

Single stars

(Literature)


Planet host

NGC6253 Age=3 Gyr, Fe/H= + 0.35

NGC 6253

M67 stars


Log Li

Age errors

2.5

2.0

1.5 ?

0 2 4 6 8

Age


Young population (1-3 Gyr)?

Old population (6-8 Gyr) ?

Age effect/bias ?


Planet HARPS Single stars

single stars HARPS -M


NO obvious relation between Li and age


How to explain ?

Baraffe & Chabrier (2010)

Episodic accretion can produce objects with central temperatures significantly

higher than the ones of the non-accreting counterparts of same mass and age.

As a consequence, lithium depletion can be severely enhanced in these objects.

Eggenberger, Maeder & Meynet (2010)

The larger efficiency of rotational mixing predicted in exoplanet host stars explains their

lithium depletion and leads also to changes in the structure and chemical composition of

the central stellar layers.


How to explain ?

Bouvier (2008)

Lithium-depleted exoplanet host stars were slow rotators on the zero-age main sequence

(ZAMS). Slow rotation results from a long lasting star-disk interaction during the PMS.

Altogether, this suggests that long-lived disks (≥5 Myr) may be a necessary condition for

massive planet formation/migration.

Vauclair (2010)

Accretion of planetary (metal-rich) material onto a star in its early phases can produce

episodes of thermohaline convection below the outer convective zone. These extramixing

phases lead to rapid lithium destruction.


Be abundances of 89 planet-host stars (red symbols) and 40 stars without

planets (blue symbols)


Be abundances determination is very difficult for stars cooler than 5300 K

We find two planet host stars which present Be depletion when compared with

analogue comparison stars but most cool main sequence stars seem to have their

Be depleted, reagrdless of the presence of planets.


T eff =6000 K

[Fe/H]=0

Fully convective

T > 2 10 6 K

Ingestion of planets &

Accretion of planetesimals

T bottom < 2 10 6 K

PMS

MS

MS

Log Li=3.3

6

Li / 7 Li=0.08

AGE=1 Myr

Log Li=2.5

6

Li / 7 Li=0.0

AGE=30 Myr

Log Li > 2.5

6

Li / 7 Li > 0.0

AGE > 50 Myr


EW( 6 Li ) ~ 5 mA

0.001

T eff =6200 K

.

6

Li / 7 Li=0.06

6

Log Li=2.5

Murray & Chaboyer (2002)

Log Li=3.2


HD 82943 Israelian et al. (Nature, 2001)

FeI

CN

0.06

0.00


HD 91889

HD 82943

Normalized Flux

FeI

CN

Wavelength

Wavelength

The Li6-test (Israelian et al. Nature, 411, 163, 2001)


SiI blend at 6708.025 A


HD 82943

1) Photometrically stable on the level of 0.006 mag (Hipparcos):

Doppler shifted components from a spot which covers only 0.6 %

of the stellar surface cannot account for the observations.

2) Stellar Flares:α+α collisions and spallation from CNO nuc.

Solar Wind/Lunar soil

Solar atmosphere

frequency

nuclei

In 6 Gyrs flares produce 1.8 10 41 nuclei

In 0.01 M sun convection zone of HD 82943 reside 1.6 10 44 nuclei !


Planetary migration

d > 5 AU

Planetary migration:

dynamical friction

d > 5 AU

Time-scale ~ 10-20 Myr

Dense gas/dust accretion disk

drag effect, torque etc

Time-scale: up to 1 Gyr

planetesimals

NO gas

0.0001M sun < M disk < 0.1M sun


Multi-body interactions:

no gas/dust, no planetesimals

Multi-body interactions &

planetesimals disk

Time-scale: up to 100 Myr

Few large planets, orbital radii evolve

at different rates.

Time-scale: up to 1 Gyr or more

No accretion disk, dust & gas

only planetesimals

?


()



(‏- (





(

...)


Tectonic & Volcanic activity

Is there enough Th, U and K ?


HD115585

Sun like star with a planetary system

Thorium

40 % more Thorium !


Sun & HD65216

VLT UVES

Osmium


Red edge

Cloud free vegetated area


&


( /)

(‏‏)‏

(‏ (-

: /

: -


(‏‏)‏

/


Thank You!

More magazines by this user
Similar magazines