Space.com — The latest observations of the odd planetary system revealed that the dusty debris disk surrounding the star Fomalhaut is much wider than previously thought. The debris belt spans a vast region of space between 14 billion and 20 billion miles (22.5 billion to 32.1 billion kilometers) around the star. Stranger still: The planet Fomalhaut b appears to approach with 4.6 billion miles (7.4 billion km) of its star at the closest point in its orbit, then swing way out to a point about 27 billion miles (43.4 billion km) away at the farthest point. Scientists call the extremes of such a planet’s path a highly eccentric orbit. Fomalhaut b’s path, scientists say, sends the planet crashing through the surrounding debris disk during its 2,000-year orbit around its parent star.
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Sounds like fun!
It doesn’t sound like a candidate for the galactic grand tour. Orbiting a star that is 14 times brighter than Sol with a close approach more distant than Neptune and then out into the Oort cloud every 2000 years it is not prime real estate.
For reference, Pluto orbits between 4.4 and and 7.3 billion miles.
I mean kilometers. Oops.
And while we’re on the subject, I don’t care what the “scientists” have to say. Pluto will always be a planet in my heart!
@ ^ dukeofomnium : Mine too. I think the IAU got that definition very badly wrong but that’s a whole other story.
Cheers Stephen “DarkSyde” Andrew – Fomalhaut b is oneof my favourite exoplanets. :-)
In case you haven’t already seen it, – the Bad Astronomer has a good post up with the latest on this here :
http://www.slate.com/blogs/bad_astronomy/2013/01/09/the_eye_of_sauron_new_hubble_pictures_of_what_may_be_a_planet_orbiting_fomalhaut.html
Which is worth reading – as is this too.
That’s one wild ride.
And still you’ll see the inhabitants of Fomalhaut B just can’t decide where to book for summer holidays this year.
In astronomers’ favorite units, the ring is 150 – 200 AU, while the orbit is 50 – 300 AU. AU = Astronomical Unite = average distance from the Earth to the Sun.
Fomalhaut is about 16.6 times brighter than the Sun, meaning that getting the amount of light from it as the Earth does from the Sun means orbiting about 4 AU away. The planet’s equilibrium temperature with the Sun, for Earthlike surface behavior, is about 30 to 80 K from its farthest to its nearest point. So it’s cold.
As to how it got into an orbit with eccentricity 0.7, it’s likely a near-collision with a similar planet. That’s the favorite hypothesis for other high-eccentricity planets, some of which have even higher eccentricities.
This of course means there’s another planet in that system to find. Possibly a Hot Jupiter, since that is one of the leading hypotheses as to how Hot Jupiters get into their close-in orbits, ie a near gravitational interaction with another planet where the more massive planet gets pushed inwards while the less massive planet is sling-shotted out into a distant eccentric orbit.
Fomalhaut b would therefore be the less massive outer planet.
Don’t know if a Hot Jupiter is detectable around Fomalhaut with our current technology, but finding one there would provide a pretty impressive confirmation of that particular formation theory.