In September 2008, astronomers announced
the confirmation of yet another exoplanet, this one orbiting the star 1RXS J160929.1-210524, an orange dwarf about 500 light years from Earth.
It was touted as the first direct image of an exoplanet orbiting a sun-like star, but that's not really the case. The system of planets around HR 8799 shown in the previous image was first observed in October 2007, and the confirmation came in July 2008. This planet, called 1RXS 1609 b, was seen in images taken in April 2008 but not announced until September.
In the exoplanet hunting game, weeks count! And the order of observations may not match the confirmation and announcements. Now imagine if planets are eventually detected in images taken earlier than any of these. How confusing would that be?
Either way, record or not, this is an interesting case. The large distance of the planet from its star - 50 billion km
(30 billion miles) - is far more than any other planet discovered. It's a struggle to understand how such a planet could have formed that far out. Perhaps it formed closer in and got tossed out by another massive planet orbiting nearby. Perhaps it formed more like a brown dwarf, collapsing from the material from which the star itself formed (planets usually form from disks of material closer in, slowly gaining mass through collisions). That seems unlikely though; that process should make objects more massive than this planet (which has about 8 times the mass of Jupiter).
We're still new at this, and observations are scarse. As we get better, we'll learn more... and solve some of the pervasive mysteries about how planets form and how they age.Original blog post: Another direct picture of a planet orbiting an alien star confirmed!
Credit: Gemini Observatory