This week I participated in a Reddit discussion with NASA scientists involved in the search for exoplanets, and other phenomena beyond our solar system. I’ve copied and pasted my questions and their answers below, but you can read the entire discussion here.
Mike: Is it possible to determine what elements might be on an exoplanet with current methods of discovery/observation? Would that affect how it blocked its star’s light?
Stephen Rinehart, Transiting Exoplanet Survey Satellite (TESS) Project Scientist: In fact, yes! With a method called transit spectroscopy, we can gain insight into the composition of the atmosphere. When you observe a transit, if you’re looking at a wavelength where the atmosphere absorbs light very well, the planet looks bigger than at wavelengths where the atmosphere doesn’t absorb well. So, the different apparent size of the planet at different wavelengths tells us what the atmospheric spectrum is, which we can then use to infer the composition of the atmosphere. – S. Rinehart
Mike: What is the most unexpected thing about exoplanets that you’ve discovered so far?
Scott Wolk, Chandra Astrophysicist at the Smithsonian Astrophysical Observatory: The Hot Jupiters. When we started,we thought all planetary systems had to look like ours, rocky planets on the inside and then gas giants at the ice line and then ice giants at the end. So people were looking for Jupiters in long (years) orbits. The discovery was so surprising that the first hot Jupiter discovered (HD114762b) was labeled a brown dwarf in the 1989 paper. When 51 Peg b was announced by the Geneva group. The San Fransisco group found that they had observed the planet, but not coded their software to report such a short period as interesting. – SJW
Steve Howell, Kepler Project Scientist: One might also consider planets the density of styrofoam, orbiting unipolar orbits, being tightly packed into a tight group and gravitationally interacting, being larger than Jupiter, orbiting their star in hours, etc. The panoply of what Kepler and other exoplanet researchers have detected is amazing. SH
Mike: Are there plans to develop different methods or instruments for detecting exoplanets in the future? Or of detecting different/more aspects about exoplanets?
Mark Clampin, James Webb Space Telescope (JWST) Observatory Project ScientistExoplanet: scientists are always working on new techniques and instrumentation for detecting and characterizing exoplanets, and to exploit new ground and space-based capabilities as they are developed. For example the James Webb Space Telescope was designed for imaging faint objects in the early universe, but we have worked hard to ensure that the instruments can also study exoplanets. MC
If you’re interested in exoplanets and “hot jupiters” you can read more about them on NASA’s website here.