Giant gas ringed planet likely causes eclipses of PSD 110 star in Orion

Artist’s impression of the giant exoplanet orbiting the star PDS 110. The planet, PDS 110b, has an estimated mass about 50 times that of Jupiter and is encircled by a ring of dust. Image credit: University of Warwick.

Astronomers have identified that the light from star PDS 110 lying approximately 1,125 light-years from Earth in the constellation of Orion, is regularly blocked by a large object, that is the giant ringed gas planet PDS 110b which up to fifty times the mass of Jupiter and encircled by a ring of dust, according to new research by an international team of astronomers, led by the University of Warwick.

PDS 110 is a rare Fe/Ge-type star, a 10-million-year-old accreting intermediate-mass star. Also known as HD 290380, IRAS 05209-0107 and 2MASS J05233100-0104237, the star is slightly larger than our Sun but has the same temperature. The distance where the star is located makes PDS 110 consistent with being a member of the Orion OB1a association, the group of very young stars northwest of the Orion Belt stars.

Now Hugh Osborn, a researcher from Warwick's Astrophysics Group, has identified that the light from this rare young star is regularly blocked by a large object - and predicts that these eclipses are caused by the orbit of this as-yet undiscovered planet.

Using data from the Wide Angle Search for Planets (WASP) and Kilodegree Extremely Little Telescope (KELT), an international team of astronomers analyzed 15 years of the PDS 110’s activity.

“We found a hint that this was an interesting object in data from the WASP survey, but it wasn’t until we found a second, almost identical eclipse in the KELT survey data that we knew we had something special,” said Hugh Osborn, a PhD student in the Astronomy and Astrophysics group at the University of Warwick, UK, and lead author of a new paper in the Monthly Notices of the Royal Astronomical Society (arXiv.org preprint) describing the discovery.

Osborn and co-authors discovered that every 808 days, the light from PDS 110 is reduced to 30% for about two to three weeks.

Two notable eclipses observed were in November 2008 and January 2011.

“What’s exciting is that during both eclipses we see the light from the star change rapidly, and that suggests that there are rings in the eclipsing object, but these rings are many times larger than the rings around Saturn,” said Dr. Matthew Kenworthy, an astronomer at Leiden Observatory.

The next eclipse event, assuming the dips in starlight are coming from an orbiting planet, is predicted to take place in September 2017, the star is bright enough that amateur astronomers all over the world and professional astronomers will be able to watch the event. If confirmed in September, PDS 110 will be the first giant ring system that has a known orbital period outside our solar system.

“September’s eclipse will let us study the intricate structure around PDS 110 in detail for the first time, and hopefully prove that what we are seeing is a giant exoplanet and its moons in the process of formation,” Osborn said.

The researchers suggest that there are moons could be forming in the habitable zone around PDS 110 - pointing to the possibility that life could thrive in this system.

The eclipses can also be used to discover the conditions for forming planets and their moons at an early time in the life of a star, providing a unique insight into forming processes that happened in our solar system.

The research, ‘Periodic Eclipses of the Young Star PDS 110 Discovered with WASP and KELT Photometry’, MNRAS, was published online May 20, 2017; doi: 10.1093/mnras/stx1249, and due to be published in the Monthly Notices of the Royal Astronomical Society.

Sources: University of Warwick, sci-news, Wikipedia