The EChO science case

摘要: The discovery of almost 2000 exoplanets has revealed an unexpectedly diverse planet population. Observations to date have shown that our Solar System is certainly not representative the general population planets in Milky Way. key science questions urgently need addressing are therefore: What made of? Why as they are? causes exceptional diversity observed compared System? EChO (Exoplanet Characterisation Observatory) been designed a dedicated survey mission for transit and eclipse spectroscopy capable observing large sample within its four-year lifetime. can target atmospheres super-Earths, Neptune-like, Jupiter-like planets, very hot temperate zones (planet temperatures 300K-3000K) F M-type host stars. Over next ten years, several new ground- space-based surveys will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which specifically focus on finding bright, nearby systems. current rapid rate would allow list be further optimised years prior EChO's launch enable atmospheric characterisation hundreds planets. Placing satellite at L2 provides cold stable thermal environment, well field regard efficient time-critical observation targets randomly distributed over sky. A 1m class telescope sufficiently achieve necessary spectro-photometric precision. spectral coverage (0.5-11 micron, goal 16 micron) SNR achieved by EChO, thanks high stability design, accurate measurement composition structure exoplanets.