For the past seven years, the W.M. Keck observatory has been observing four large exoplanets that orbit the same star, possibly in resonance with one another. Jason Wang, an astronomy graduate student at the University of California who has been working with the research team, describe these planets’ orbits as being in a nearly precise 1-2-4-8 resonance with one another.
The planets orbit a young star named HR 8799 with orbital periods ranging from about 40 to about 400 years long. None of them have completed an orbit since the research team headed by Dr. Christian Marois of the National Research Council at Canada’s Herzberg Institute of Astrophysics announced the discovery of three of the four planes in 2008. Although the fourth may have been observed by instruments on the Hubble Space Telescope as early as 1998, it was only formally discovered after upgraded image processing software was installed.
Astronomers are currently watching HR 8799 and its planets to see if the system is stable. Because the planets are so far apart and the closest one is 15 times more distant from its star than Earth is from the sun, it is possible that one of them may be ejected from the star system and become an “orphan” planet. The distance between the innermost planet and its host star also leaves room for some as-yet-undiscovered “rocky” planets that may be orbiting closer to the star.
HR 8799 is a relatively young star at 60 million years old and shines about five times brighter than the sun. It resides about 129 light years from Earth in the Pegasus constellation, putting it in the same constellation as 51 Pegasi, the star around which the first detected exoplanet orbits.
Direct Imaging Of Exoplanets Used For The First Time
The three planets discovered orbiting HR 8799 in 2008 were among the first to be discovered using direct imaging. The black dot in the center blocked out light from the star to make it possible to view the planets directly. Jason Wang put together an animation using images captured by Dr. Marois since 2009 and used a motion interpolation algorithm to plot their orbits.
While animations like this are unlikely to be used in any big-budget science fiction movies in the near future, the ability to use direct imaging could help scientists refine techniques used to discover exoplanets. Scientists like Wang also hope that animations like this can help keep the public interested by showing what these systems might look like as seen from Earth.