A young star known as HR8799 and its family of four planets is being explored by astronomers in the greatest detail ever using the Large Binocular Telescope (LBT) in southeastern Arizona. The investigation is part of the LEECH (LBT Exozodi Exoplanet Common Hunt) survey and is the first system in the study for which results have been released.
The star HR8799 is located 130 light years from Earth, and astronomers believe the stellar body is just 30 million years old. By comparison, our own sun formed roughly 4.5 billion years in the past. Three exoplanets were detected in 2008, and a fourth was found two years later. This planetary system was the first to ever be directly imaged by astronomers.
"This star was therefore a target of choice for the LEECH survey, offering the opportunity to acquire new images and better define the dynamical properties of the exoplanets orbiting," Christian Veillet, director of the Large Binocular Telescope Observatory (LBTO), said.
The Leech program, designed to detect young exoplanets by studying stars in infrared light, began in February 2013. The L/M-band infrared camera (LMIRCam) is installed at the observatory studies electromagnetic radiation in what is known to astronomers as the L band, or LBT Interferometer (LBTI). Most telescopes glow at this band, with wavelengths around four microns, reducing the ability of observatories to examine stellar objects shining at the same frequencies.
"However, with LBT, everything about the telescope, its adaptive optics system and science camera have been optimized to minimize this glow. As a result, LEECH is more sensitive than previous exoplanet imaging surveys, and this new image of HR 8799 is proof," Andy Skemer from the University of Arizona and leader of the survey, stated in a press release.
The study was able to narrow down the range of masses for the four known planets in the system. Astronomers were also able to determine some of the physical characteristics of an unseen inner fifth planet that is suspected to orbit around the star.
Investigation of the system revealed that the four visible planets interact with each other though gravity, which reveals a minimum mass for the worlds. However, if the planets were too massive, the system would collapse, a finding that places an upper limit to the size of the alien worlds.
Each planet takes roughly twice as long to go around HR8799 as its closest neighbor heading toward the star, a characteristic known as a resonance. The innermost of these worlds orbits roughly 15 times further from its star than the distance between the sun and Earth. The study also showed the solar system is relatively stable, with no collisions between worlds likely over the next few million years.
Analysis of the HR8799 system was detailed in the journal Astronomy and Astrophysics.
