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The infrared spectra of 2MASS 0249 c (high) and beta Pictoris b (low) are similar. Both objects are of comparable mass and formed in the same stellar nursery. Unlike 2MASS 0249c, the Pictoris B beta gets much closer to its massive star and is embedded in a brilliant circumstellar disc. Credit: T. Dupuy, ESO / A.-M. Lagrange et al.
Astronomers from the island of Hawaii have found a new planet that seems to be almost identical to one of the planets gaseous extrasolar gases best studied. However, the newly discovered planet differs in an important way: its origin.
"We have found a gas giant planet that is a virtual twin of a previously known planet, but it looks like two objects formed in a different way," said Trent Dupuy, astronomer at the Observatory Gemini and leader of the study
Stars form in clusters, forming energy and size in stellar nurseries filled with gas and dust, and finally derive from their place of birth. Because of this exodus, astronomers believe that there are planets born at the same time in the same stellar nursery, but are stars in orbit that have moved away from each other.
"To this day, Exoplanets found by direct imaging have been essentially, "said Michael Liu, astronomer at the Institute of Astronomy at the University of Hawaii, and collaborator at this work. "To find two exoplanets with almost identical appearances and yet forming so differently opens a new window to understand these objects."
Dupuy, Liu and their collaborators identified the first case of such a planetary doppelgänger. An object is known for a long time: one of the first planets discovered by direct imaging in 2009, called the planet beta-13 of Jupiter Pictoris b. The new object, dubbed 2MASS 0249 c, has the same mass, the same brightness and the same spectrum as the beta Pictoris B.
After discovering this object with the Canada-France-Hawaii telescope (CFHT), Dupuy and his collaborators determined that 2MASS 0249c and beta Pictoris b were born in the same stellar nursery. This makes the two objects not only look like real brothers and sisters.
However, planets orbit very different stars. The host of the Beta Pictoris b is a star 10 times brighter than the Sun, while 2MASS 0249 c orbits around a pair of brown dwarfs that are 2000 times weaker than the Sun. Moreover, the beta Pictoris b is relatively close to its host – about nine astronomical units (AU, distance from the Earth to the Sun), while 2MASS 0249 c is 2000 AU from its binary host.
These radically different conditions suggest that the education of the planets did not resemble each other at all. The traditional image of the gaseous giant formation dictates that the planets start as small rocky cores around their host star and grow up by accumulating gas from their star's disk – which is probably the creation of the Pictoris beta b. In contrast, the host of 2MASS 0249 did not have enough disk to make a gaseous giant, so the planet was probably formed by accumulating gas from its original stellar nursery.
"2MASS 0249 c and Beta Pictoris B show us this nature has more of a way to make very similar exoplanets," says Kaitlin Kratter, astronomer at the University of Arizona and collaborator at this job. "Beta Pictoris b's probably formed as we think for most gas giants, starting with tiny grains of dust. In contrast, 2MASS 0249 c looks like a brown underweight dwarf that has formed as a result of the collapse of a cloud of gas. They are both considered exoplanets, but 2MASS 0249 c illustrates that such a simple classification can obscure a complicated reality. "
The team identified 2MASS 0249c using CFHT images, and their repeated observations revealed that this object is in orbit at great distance from its host.The system belongs to the group in motion beta Pictoris, a very scattered star set named for its famous star of hosting in planet.The observations of the team at WM The observatory of Keck determined that the host is actually a closely spaced pair of brown dwarfs.Therefore, in total, the 2MASS 0249 system includes two brown dwarfs and a giant gas planet.The 2MASS 0249 c tracking spectroscopy with NASA's infrared telescope facility and telescope 3.5 meters from the Astrophysical Research Consortium at the Apache Point Observatory have demonstrated that it is strangely resembling the Beta Pictoris B.
The 2MASS 0249 System is an Attractive Target for Studies The pl most directly imaged anets are very close to their host stars, preventing detailed studies of planets due to the bright light generated by their stars. On the other hand, the very large separation of 2MASS 0249 c from its host binary will make the measurements of properties like its surface and its composition much easier, which will allow to better understand the characteristics and the origins of the gaseous giant planets.
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