HD 106906b, a giant exoplanet discovered last year sitting at a large distance from its parent star, may have been kicked out of its birthplace in a process similar to what may have happened early in the history of our Solar System.
These are two direct images of the super-Jupiter HD 106906b and the cometary dust surrounding the young star HD 106906. The wider field in blue shows Hubble data where the star’s blinding light is artificially eclipsed. A new discovery in these Hubble observations is an asymmetric nebulosity indicating a dynamically disturbed system of comets. Surprisingly, HD 106906b is located 21 degrees above the plane of the nebulosity. The circular orange inset shows a region much closer to HD 106906. Image credit: Paul Kalas / University of California, Berkeley.
HD 106906b is a so-called super-Jupiter with a mass 11 times that of Jupiter.
It orbits its host star – the white main-sequence star HD 106906A – at more than 20 times the average Neptune-Sun distance.
The star is similar to our Sun, but much younger: about 13 million years old, and is located in the constellation Crux, approximately 300 light-years away from Earth.
New images from the NASA/ESA Hubble Space Telescope and the Gemini Planet Imager (GPI) of this system show that the star has a lopsided comet belt indicative of a very disturbed system, and hinting that planet interactions that roiled the comets closer to the star might have sent the exoplanet into exile as well.
According to an international team of astronomers, led by Dr Paul Kalas of the University of California, Berkeley, HD 106906b may have a dusty ring system of its own.
“We think that the exoplanet itself could have captured material from the comet belt, and that the planet is surrounded by a large dust ring or dust shroud. We conducted three tests and found tentative evidence for a dust cloud, but the jury is still out,” Dr Kalas said.
“The measurements we made on the planet suggest it may be dustier than comparison objects, and we are making follow-up observations to check if the planet is really encircled by a disk – an exciting possibility,” added team member Abhi Rajan, a graduate student at Arizona State University.
Such planets are of interest because in its youth, our Solar System may have had planets that were kicked out of the local neighborhood.
This is an artist’s impression of the exoplanet HD 106906 b in a distant orbit around its host star. Image credit: NASA / JPL-Caltech.
“We know that our own belt of comets, the Kuiper belt, lost a large fraction of its mass as it evolved, but we don’t have a time machine to go back and see how it was decimated,” Dr Kalas said.
“One of the ways, though, is to study these violent episodes of gravitational disturbance around other young stars that kick out many objects, including planets.”
The disturbance could have been caused by a passing star that perturbed the inner planets, or a second massive planet in the system.
The astronomers looked for another large exoplanet closer to HD 106906A that may have interacted with the exoplanet, but found nothing outside of a Uranus-sized orbit.
The planetary system HD 106906A is the subject of a study accepted for publication in the Astrophysical Journal (arXiv.org preprint).
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Paul G. Kalas et al. 2015. Direct imaging of an asymmetric debris disk in the HD 106906 planetary system. ApJ, accepted for publication; arXiv: 1510.02747
