First direct image of extrasolar planets

10.7 billion miles

Fomalhaut A is 16 times brighter than the Sun and is 200 million years old.

The planet has a mass of 3 Jupiter’s masses and orbital period 872 years.

It is too bright for its size and is probably still contracting, or has a ring.

Star-Birth Clouds in M16 (Eagle Nebula). J. Hester and P. Scowon (Arizona St. Univ.), November 2, 1995. Taken with NASA Hubble Space Telescope, WFPC2

We know there should be planets around other stars.How to find them???

M > 2000 M

JUPITER SHINES WEAKER THAN THE SUN:

1 000 000 000 TIMES (visible light)

50 000 TIMES (infrared)

5 000 TIMES (mm and sub-mm)

JUPITEROBSERVED FROM THE NEAREST

STAR

0.1” DISTANT FROM THE SUN

„DROWNED” IN SUNSHINE !!

POPULARVIEW

REALITY

X = CENTER OF MASS

SYSTEM VIEWEDPOLE-ON (RARE)

Center of Mass

(SLIDESHOW MODE ONLY)

...BUT

THE PLANET CANNOT BE SEEN

MOTIONS OF THE STAR

BETRAYITS PRESENCE !

X

EARTH

X

JUPITER

150 000 000 km

30 km/s

450 km

9 cm/s

780 000 000 km

13 km/s

750 000 km

13 m/s

2010

2000

2005

1995

1990

2015

2020

0.002”

MOTIONS OF THE SUN VIEWED FROM A STAR 30 LIGHT YEARS AWAY

0.002’’ IS THE ANGULAR SIZE OF A MAN ON THE MOON OR A STANDARD NEWSPAPER FONT 300 KM AWAY Unobservable!

STELLARWOBBLE

RECEDING:

REDDER

APPROACHING:

BLUER

The Doppler Effect

The light of a moving source is blue/red shifted by

/0 = vr/c

0 = actual wavelength

emitted by the source

Wavelength change due to

Doppler effect

vr = radial velocity

Blue Shift (to higher frequencies)

Red Shift (to lower frequencies)

vr

1 Angstrom = 10-8 cm

PLANET DETECTION DUE TO STELLAR WOBBLE

-50

-100

0

100

50

m/s

0 321 days

K

P ito the observer

normal to the orbit

V

K = Vsin i

Only the function of masses and inclination anglecan be measured

ANOTHEREFFECT:

TRANSIT

PLANET IN FRONTOF THE STAR

TIMEBR

IGH

TN

ES

S

TRANSIT

1%

LIGHTCURVE

Measure the radius of the planet, know the mass -> find the mean density!!

First direct detection of radiation from extrasolar planet!

Spitzer Infrared Telescope

First detection of any carbon-bearing molecule on a planet outside the Solar System! Swain et al., Nature, March 2008

Also confirmed previous discovery of water on this planet

326 extrasolar planets are found so farhttp://planetquest.jpl.nasa.gov/

Planetary system of And

Solar system

0.06 AU4.5 days0.75 MJ

2.5 AU3.5 years

4 MJ

0.85 AU242 days

2 MJ

0.39 AU89 days

0.73 AU228 days

1 AU1 year 1.54 AU

1.9 years

Source: Harvard-Smithsonian CfA

Are we alone in the Universe??Are there any Earth-like planets in habitable zones around stars?

Habitable zones

April 25, 2007: Discovery of the first Earth-like planet in the habitable zone!!

Red dwarf

What would be the signs of life on other planets??

Signs of life in the spectrum: