Chinese- international collaboration solved the central question: ”How common are planets like the Earth”

Jupiter-Saturn like exoplanets are uncommon – Are Earth-like exoplanets common? Is our solar system ”normal” or is something unusual the cause for our existence? SONG is particular sensitive to planets as in our solar system -- are they common or rare?. Design driver: 5 years of observation will tell number of Earths in the Galaxy Exoplanet research with SONG:

Primarily oxygen-rich stars are orbited by giant exoplanets 16 stars of 250,000 toward the galactic centre showed transiting exoplanets Doppler and transit planets dominate the number of known exoplanets –-- This will change in the future 420/ 70 of 440 known 110 expected from solar neighbourhood

Since 2004 we have searched for exoplanets using the Danish 1.54m telescope at ESO La Silla dedicated 4 months/year for microlensing search. SONG can do Doppler and microlensing, but will do microlensing 200 times more efficient that traditional telescopes.

Habitable exoplanets: orbits: 0.4 AU – 4 AU around stars A5 - M0 ( M_sun) with main sensitivity to exoplanets as all the planets in our solar system ¾ of all stars ¼ of all stars SONG: first telescope

lens star

Observed 5.5 Earth-mass planet Hypothetical 1 Earth-mass planet OB05390 is on the limit of what existing telescopes can observe

microlensning = observations in dense stellar fields 10 microlensing exoplanets are now known; incl a 3 and a 5 Earth-mass,terrestrial planet in an Earth-like orbit. SONG will be able to detect Mars mass planets in terrestrial orbits

” Lucky Imaging” cameras at the SONG telescopes will reach almost as sharp images as a space-telescope. Normal camera Lucky imaging camera

MOA finding chart (1.8m NewZeeland) Lucky Imaging 1.54m Danish, Chile VLT/NACO 8m

mikrolinser --jordlignende exo-planeter To observe smaller mass planets, requires to be able to resolve smaller source stars (i.e Lucky Imaging if fields are crowded), and observe more events (i.e. faster telescopes, observing a larger fraction of the year and night). SONG is a follow-up survey able to find small planets

Pan-STARRS at Haleakala, Maui, Hawaii: next step in NEOsearch Aim: to identify ”all” NEOs > 1km, and 99% > 300m. It goes 5 mag (i.e. a factor 100) deeper than previous surveys, and is expected to identify 10 mill new main belt asteroids, and > new NEOs and TNOs First of 4 planned telescopes has started The camera has 1.4 billion pixels and a field of 7 sqr deg pr exposure. Two exposures pr minute of 2Gb size 0.3” resolution. Vlim=24 (intg 29.4) 6000 sqr.deg. pr night = the full sky scanned every week.

Large Synoptic Survey Telescope LSST will detect NEOs to 100 m diam. One 8.4 m mirror, 3 Gpixel CCD, Vlim = 27 full sky cover every 3 nights from 2014; 30 TB/night 10 sqr.deg. in each 15 sec exposure at 0.2”resolution in 5 bands, 4000Å-1.06mu 2.7km Cerro Pachon in North Chile

VYSOS-5” (right) and Mauna Loa Observatory in Hawaii and VYSOS-6” (below) at Cerro Armazones Observatory in Atacama, Chile. Tests with microlensing alerts in the whole Galactic plane are now being performed at

mikrolinser --jordlignende exo-planeter The SONG telescopes have: Smaller PSF (factor 9) Better throughput (factor 1.5) Faster slew and pointing (factor 2) Broader filters (factor 4) Better use of the year (factor 2) Roughly speaking, SONG can reach 3 mag fainter stars (=see smaller planets) with a 10 times higher efficiency => statistics on Earth-Mars like planets in 5 years Will we have microlenses enough to observe?

Difraction limit: For a 1m mirror, the diffraction limit is 0.15” at 5000 Å 0.25” at 8000 Å The best seeing at La Silla, DK1.54m is 0.8”; typical seeing is 1” to 1.5” Lucky Imaging tests: 0.35”

To understand whether we can benefit from surveys in the general Galactic plane, I have made a simple Galactic model : Bulge: Extinction: 0.63mag per kpc Disk: cylinder of r = 15 kpc, h = 2 kpc

We now integrate the total Einstein areas out through a cone of 1 square degree of the sky The Einstein-area is the probability of a source star at distance ds being linsed. When multiplied by the number of source stars at ds, it gives the total number of lensing events at any given time of some baseline magnitude. The number per year is then approx. 52/3 times this number. This integration with the simple Galactic model gives good agreement with the number and distribution of OGLE events, and predict that the number of events could be doubled by looking out of center with a modest sized telescope.

A global network of 1m telescopes for long time series observations High resolution imaging for microlensing at summer time High resolution spectrograph for low mass RV observations in winter

First astrometric detection of an exoplanet from ground: VB10b May GAIA expects to identify 10,000 giant exoplanets within 200 pc

First 9 direct imaging detected exoplanets indicate a huge future potential for this method

Transit accuracy of 0.5 milli-mag from the ground (DK1.54m); timing accuracy of 10 s WASP-2 WASP-6 The Kepler satellite has 5 times better photometric accuracy (0.1 milli-mag) Many more transiting exoplanets will be announced in coming years.