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It'll be in the near-infrared, but the light won't be separated from the star. How they observe the atmosphere is that when the exoplanets transit, they block o

It'll be in the near-infrared, but the light won't be separated from the star. How they observe the atmosphere is that when the exoplanets transit, they block out different amounts of light at different wavelengths. From that, one can deduce an atmospheric spectrum.

mturmon 10y ago
Absolutely right. Here is a recent paper on exoplanet atmosphere characterization by JWST: https://arxiv.org/abs/1511.05528 https://arxiv.org/abs/1511.05528 -- the overview is at https://jwst.nasa.gov/origins.html https://jwst.nasa.gov/origins.html As you say, the contrast between seeing (star + planet) during a transit, versus star alone, is enough to identify absorption of infrared light by some chemical species. The simulations in the above paper basically show they can infer some chemical abundances (carbon, oxygen) and some atmospheric parameters (inversion layers) for Neptunes and Jupiters. But probably not for Earths, so not for the system in the OP. Even for big, thick atmospheres, these spectroscopic characterizations take a lot of observation time (like, days). The race is indeed on to develop instruments and algorithms for this problem -- e.g., detecting CH4 or CO2 in an exo-Earth atmosphere. There's feverish activity in the Astronomy community around this, and post-JWST missions are being formulated to tackle the problem.
sand500 10y ago
Would using a shield to block out the star be good enough to image the planets? https://en.m.wikipedia.org/wiki/New_Worlds_Mission https://en.m.wikipedia.org/wiki/New_Worlds_Mission
- semaphoreP 10y ago
  It will depend on the size of the telescope, but for all practical purposes, these planets are too close to their star to see directly. A starshade will be good for Earth-like planets at Earth-like separations around Sun-like stars though.
- mturmon 10y ago
  There are a lot of approaches. The Spitzer results in the OP here, and the JWST concept above, is about characterizing exoplanet atmospheres during a transit using spectroscopy. The concept you link is a "starshade". It's a sister concept to a "coronagraph" -- both use an occulting disk to block out the light from the host star, so that a non-transiting exoplanet can be observed. One goal is to image exoplanets directly, and another is to gather spectra for characterization. One of two current mission studies doing studies of the two approaches is HabEx (http://www.jpl.nasa.gov/habex/ http://www.jpl.nasa.gov/habex/). Obviously, the starshade is more complex/cumbersome/expensive. Using one method or another, you have to achieve a contrast of about 1e10 between the star and the exoplanet. For every 1e10 photons that come in from the host star, your starshade/coronagraph has to let at most one get through to the detector.

mturmon 10y ago

Absolutely right. Here is a recent paper on exoplanet atmosphere characterization by JWST: https://arxiv.org/abs/1511.05528 https://arxiv.org/abs/1511.05528 -- the overview is at https://jwst.nasa.gov/origins.html https://jwst.nasa.gov/origins.html As you say, the contrast between seeing (star + planet) during a transit, versus star alone, is enough to identify absorption of infrared light by some chemical species. The simulations in the above paper basically show they can infer some chemical abundances (carbon, oxygen) and some atmospheric parameters (inversion layers) for Neptunes and Jupiters. But probably not for Earths, so not for the system in the OP. Even for big, thick atmospheres, these spectroscopic characterizations take a lot of observation time (like, days). The race is indeed on to develop instruments and algorithms for this problem -- e.g., detecting CH4 or CO2 in an exo-Earth atmosphere. There's feverish activity in the Astronomy community around this, and post-JWST missions are being formulated to tackle the problem.

sand500 10y ago

Would using a shield to block out the star be good enough to image the planets? https://en.m.wikipedia.org/wiki/New_Worlds_Mission https://en.m.wikipedia.org/wiki/New_Worlds_Mission

semaphoreP 10y ago
It will depend on the size of the telescope, but for all practical purposes, these planets are too close to their star to see directly. A starshade will be good for Earth-like planets at Earth-like separations around Sun-like stars though.
mturmon 10y ago
There are a lot of approaches. The Spitzer results in the OP here, and the JWST concept above, is about characterizing exoplanet atmospheres during a transit using spectroscopy. The concept you link is a "starshade". It's a sister concept to a "coronagraph" -- both use an occulting disk to block out the light from the host star, so that a non-transiting exoplanet can be observed. One goal is to image exoplanets directly, and another is to gather spectra for characterization. One of two current mission studies doing studies of the two approaches is HabEx (http://www.jpl.nasa.gov/habex/ http://www.jpl.nasa.gov/habex/). Obviously, the starshade is more complex/cumbersome/expensive. Using one method or another, you have to achieve a contrast of about 1e10 between the star and the exoplanet. For every 1e10 photons that come in from the host star, your starshade/coronagraph has to let at most one get through to the detector.