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, 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: TIMES (visible light) TIMES (infrared) TIMES (mm and sub-mm)
JUPITER OBSERVED FROM THE NEAREST STAR 0.1” DISTANT FROM THE SUN „DROWNED” IN SUNSHINE !!
POPULAR VIEW
REALITY X = CENTER OF MASS SYSTEM VIEWED POLE-ON (RARE)
Center of Mass (SLIDESHOW MODE ONLY)
...BUT THE PLANET CANNOT BE SEEN MOTIONS OF THE STAR BETRAY ITS PRESENCE !
X EARTH X JUPITER km 30 km/s 450 km 9 cm/s km 13 km/s km 13 m/s
” 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!
STELLAR WOBBLE RECEDING: REDDER APPROACHING: BLUER
The Doppler Effect The light of a moving source is blue/red shifted by / 0 = v r /c 0 = actual wavelength emitted by the source Wavelength change due to Doppler effect v r = radial velocity Blue Shift (to higher frequencies) Red Shift (to lower frequencies) vrvr
1 Angstrom = cm
PLANET DETECTION DUE TO STELLAR WOBBLE m/s 0321 days K P i to the observer normal to the orbit VV K = V sin i
Only the function of masses and inclination angle can be measured
ANOTHER EFFECT: TRANSIT PLANET IN FRONT OF THE STAR
TIME BRIGHTNESS TRANSIT 1% LIGHT CURVE 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 far
Planetary system of And Solar system 0.06 AU 4.5 days 0.75 M J 2.5 AU 3.5 years 4 M J 0.85 AU 242 days 2 M J 0.39 AU 89 days 0.73 AU 228 days 1 AU 1 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: