海角大神

Astronomers watching the repeated and drawn-out dimming of a relatively nearby聽Sun-like star have interpreted their observations to indicate an eclipse by a gigantic exoplanet鈥檚聽complex聽ring system, similar to Saturn鈥檚 except much, much bigger.聽What鈥檚 more, apparent gaps聽and varying densities of the rings imply the presence of at least one large exomoon, and perhaps even more in the process of聽formation!

J1407 is a main-sequence orange dwarf聽star about 116 light-years away. Over the course of 57 days in spring of 2007 J1407 underwent a 鈥渃omplex series of deep eclipses,鈥澛爓hich an international team of astronomers asserts is the result of a ring system around the massive orbiting exoplanet J1407b.

鈥淭his planet is much larger than Jupiter or Saturn, and its ring system is roughly 200 times larger than Saturn鈥檚 rings are today,鈥� said Eric Mamajek, professor of physics and astronomy at the University of Rochester in New York. 鈥淵ou could think of it as kind of a super Saturn.鈥�

The observations were made through the聽SuperWASP聽program, which uses ground-based telescopes to watch for the faint dimming of stars due to transiting exoplanets.

The first study聽of the eclipses and the likely presence of the ring system was published聽in 2012, led by Mamajek. Further analysis by the team estimates the number of main ring structures to be 37, with a large and clearly-defined gap located at about 0.4 AU (61 million km/37.9 million miles) out from the 鈥渟uper Saturn鈥� that may harbor a satellite nearly as large as Earth, with an orbital period of two years.

Watch an animation of the team鈥檚 analysis of the J1407/J1407b eclipse below:

The entire expanse of J1407b鈥檚 surprisingly dense rings stretches for 180 million km (112 million miles), and could contain聽an Earth鈥檚 worth of mass.

鈥淚f we could replace Saturn鈥檚 rings with the rings around J1407b,鈥� said Matthew Kenworthy from聽Leiden Observatory聽in the Netherlands and lead author of the new study, 鈥渢hey would be easily visible at night and be many times larger than the full Moon.鈥�

Saturn鈥檚 relatively thin main rings are about 250,000 km (156,000 miles) in diameter. (Image: NASA/JPL-Caltech/SSI/J. Major)

These聽observations could be akin to a look back in time to see what Saturn and Jupiter were like as their own system of moons were first forming.

鈥淭he planetary science community has theorized for decades that planets like Jupiter and Saturn would have had, at an early stage, disks around them that then led to the formation of satellites,鈥� according to Mamajek. 鈥淗owever, until we discovered this object in 2012, no one had seen such a ring system. This is the first snapshot of satellite formation on million-kilometer scales around a substellar object.鈥�

J1407b itself is estimated to contain聽10-40 times the mass of Jupiter 鈥� technically, it might聽even be a brown dwarf.

Further observations will be required to observe another transit of J1407b and obtain more data on its rings and other physical characteristics as its orbit is聽about ten Earth-years long. (Luckily聽2017 isn鈥檛 that far off!)

The team鈥檚聽report聽has聽been accepted for publication in the聽Astrophysical Journal.

Source:聽University of Rochester. Image credit: Ron Miller.

A graphic designer in Rhode Island, Jason Major writes about space exploration on his blog聽Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!

Originally posted on Universe Today.