In yet another first for the mediocrity of the solar system, Saturn appears not to have the largest ring system: astronomers Matthew Kenworthy and Eric Mamajek have found an extrasolar ring system 200 times larger than Saturn's. If Saturn's rings were the size of those around J1407b, they would easily be visible from Earth and many times the apparent size of the full moon. J1407b is much more massive than Saturn, and is probably a brown dwarf.
The light curve of 1SWASP J140747.93-394542.6, a ∼16 Myr old star in the Sco-Cen OB association, underwent a complex series of deep eclipses that lasted 56 days, centered on April 2007. This light curve is interpreted as the transit of a giant ring system that is filling up a fraction of the Hill sphere of an unseen secondary companion, J1407b. We fit the light curve with a model of an azimuthally symmetric ring system, including spatial scales down to the temporal limit set by the star's diameter and relative velocity. The best ring model has 37 rings and extends out to a radius of 0.6 AU (90 million km), and the rings have an estimated total mass on the order of 100MMoon. The ring system has one clearly defined gap at 0.4 AU (61 million km), which we hypothesize is being cleared out by a <0.8M⊕ exosatellite orbiting around J1407b. This eclipse and model implies that we are seeing a circumplanetary disk undergoing a dynamic transition to an exosatellite-sculpted ring structure and is one of the first seen outside our Solar system.
The search is on to find more "exoring" systems.
We also have the first report of a Neptune-sized exoplanet HAT-P-11b with water vapor in its atmosphere; previous reports of water vapor in atmospheres of explanets were of Jupiter-sized planets. Neptune's diameter is about four times that of Earth, so the findings of water vapor are getting closer to terrestrial sized exoplanets, which are harder to detect and study. The team used data from the Kepler, Spitzer and Hubble space telescopes. Since Earth's atmosphere is full of water vapor, to see absorption lines from water vapor in the atmosphere of another planet, you must look from above the Earth's atmosphere. The ESA's CHEOPS mission, which will launch in 2017, will search for nearby Earth to Neptune sized planets and study their atmospheres, including searching for water and biomarkers.