Astronomers have unveiled what is likely the first picture of a planet around a normal star similar to the Sun. Using the Gemini North telescope on Mauna Kea in Hawaii, astronomers from the University of Toronto imaged the young star 1RXS J160929.1-210524, which lies about 500 light-years from Earth and a candidate companion of that star. They also obtained spectra to confirm the nature of the companion, which has a mass about eight times that of Jupiter, and lies roughly 330 times the Earth-Sun distance away from its star. For comparison, the most distant planet in our solar system, Neptune, orbits the Sun at only about 30 times the Earth-Sun distance. The parent star is similar in mass to the Sun, but is much younger. â€œThis is the first time we have directly seen a planetary mass object in a likely orbit around a star like our Sun,â€ said David LafreniÃ¨re, lead author of a paper detailing the discovery. â€œIf we confirm that this object is indeed gravitationally tied to the star, it will be a major step forward.â€
Until now, the only planet-like bodies that have been directly imaged outside of the solar system are either free-floating in space (i.e. not found around a star), or orbit brown dwarfs, which are dim and make it easier to detect planetary-mass companions.
The existence of a planetary-mass companion so far from its parent star comes as a surprise, and poses a challenge to theoretical models of star and planet formation. “This discovery is yet another reminder of the truly remarkable diversity of worlds out there, and it’s a strong hint that nature may have more than one mechanism for producing planetary mass companions to normal stars,â€ said team member Ray Jayawardhana.
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The teamâ€™s Gemini observations took advantage of adaptive optics technology to dramatically reduce distortions caused by turbulence in Earthâ€™s atmosphere. The near-infrared images and spectra of the suspected planetary object indicate that it is too cool to be a star or even a more massive brown dwarf, and that it is young.
While it could be a chance alignment between the object and the young star, it will take up to two years to verify that the star and its likely planet are moving through space together. â€œOf course it would be premature to say that the object is definitely orbiting this star, but the evidence is extremely compelling. This will be a very intensely studied object for the next few years!â€ said LafreniÃ¨re.
Team member Marten van Kerkwijk described the groupâ€™s search method. â€œWe targeted young stars so that any planetary mass object they hosted would not have had time to cool, and thus would still be relatively bright,â€ he said. â€œThis is one reason we were able to see it at all.â€
The Jupiter-sized body has an estimated temperature of about 1800 Kelvin (about 1500ÂºC), much hotter than our own Jupiter, which has a temperature of about 160 Kelvin (-110ÂºC), and its likely host is a young star of type K7 with an estimated mass of about 85% that of the Sun.
â€œThis discovery certainly has us looking forward to what other surprises nature has in stock for us,â€ said Van Kerkwijk.
Read the team’s paper here.
Source: Gemini Observatory