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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: