At this point we’ve found planets in a enough places that I shouldn’t still be surprised when a neat new world is found in a neat new place. Nevertheless, I found myself awed by a new discovery of a new planet with a 3.69 year period orbiting in a close binary.
This particular discovery caught my attention for two reasons. First off, the data on this object spans ~14 years – that is a lot of data to put together. Second, this is a really close binary to have a planet! They found a planet (2.96 Jupiter masses or larger) orbiting 2.63 AU from a star that has a companion at 17.23 AU. This system is HD196885A and the announcement came in a paper with A.C.M. Correia as lead author.
Imagine the chaos involved in forming this little world. Its Sun, an F8 star, is a bit brighter (2.4 Solar Luminosities) and a bit larger (1.33 Solar Masses) than our own Sun. While this star was forming, it flared and crackled with high-energy outbursts. Meanwhile, its red dwarf companion collapses into its own violent beginning; red dwarfs also go through a terrible toddler phase of coronal mass ejections. Between these two angry youth, this planet settled into an orbit around the larger star, and pulled itself together to grow into a gasy giant. Now, 2 billion years into its evolution, the F star has settled down into a few billion years of peace and quiet. Eventually, the F star will bloat up into a red giant, go through a new round of shape shifting as it bloats and shrinks and bloats again. All the while, the planet will sit a possibly safe distance away, watching as its main source of heat and light falters and fails and eventually collapses almost completely into a white dwarf star. As the F star’s atmosphere floats away, it will form a planetary nebula that enshrodes this new found gas planet and its M-star guardian. As that white dwarf cools into ash, the dwarf planet will continue to glow, allowing the planet to experience a no onger heliocentric series of seasons, as it orbits toward and away from its secondary warmth.
What an odd fate this newly discovered planet has had and will see. What a weird place to find a planet. It really seems that alien worlds can be found in perhaps any stellar environment.
image credit: NASA/JPL-Caltech