I was extremely stoked when I read an article in January of this year that the Kepler2 mission found three Earth-sized objects (one possibly in the habitable zone) transiting a star only 150LY away. I haven't heard anything since, not even if this star and planets (confirmed) have been given a Kepler designation. I guess I would like to know if JWST or some other upcoming mission will be able to give us more info on this system. I can't imagine how excited I will be if TESS gives us something even closer!!

  • $\begingroup$ I just found out that the Kepler designation of this star is K2-3 and, of the 3 planets b,c and d, K2-3d is in the habitable zone. Radius of planet d is 1.5 R(Earth). Kepler 2 has also found a planet even closer at 111 LY, but it is probably a mini-Neptune (K2-18b). These are exciting because the planets transit meaning atmosphere follow up! $\endgroup$ Sep 25, 2015 at 3:20

1 Answer 1


Beichman et al. (2016) used the Spitzer Space Telescope to view two systems, EPIC 202083828 (one planet) and the aforementioned EPIC 201367065 (three planets), also known as K2-3. The authors describe several ways in which the observations by Spitzer complement the Kepler data:

  • Spitzer has better sampling while maintaining the same signal-to-noise ratio, constraining various orbital parameters even more.
  • Observations by Spitzer occurred over twelve months after the Kepler observations, allowing for more detailed information on the position and orbits of the planets over time.
  • Limb darkening is less of an issue in Spitzer's observations than it was in Kepler's data.
  • Spitzer can reject false transit positives by looking at how the transit depth changes over different wavelengths.
  • There is less noise from the stellar photosphere in infrared bands.

All of this led to much lower uncertainties in parameter observations in Spitzer's data alone; combined with Kepler's observations, the uncertainties were reduced even further. Period estimates and transit depths, for instance, saw significant improvement.

Finally, the authors recommend that the system be observed by the James Webb Space Telescope. That won't be launched for another two years, but I suspect its versatility over various wavelengths will better constrain data from EPIC 201367065 and other systems.

Crossfield et al. (2015) say that the James Webb Space Telescope has the capability to detect spectral signs in the atmospheres of the planets, based on certain models (Hubble could also observe them). I don't think JWST has been assigned specific targets that include this system, but that's just a guess.

In the case of the first system measured by Beichman et al., EPIC 202083828, ground-based telescopes could also give more information about spectroscopy to rival JWST, according to Schlieder et al. (2016). Perhaps EPIC 201367065 could also be observed by these telescopes.


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