An international team of astronomers has discovered one of the youngest and brightest free-floating, planet-like objects within relatively close proximity to the Sun.
An artist’s impression of a free-floating planet-like object. Image credit: MPIA / V. Ch. Quetz.
The object in question, 2MASS J11193254-1137466 (2MASS J1119-1137 for short), is only 10 million years old, making it a ‘baby’ by planetary standards.
It is between 4.3 and 7.6 times the mass of Jupiter, and hence falls in the mass range between a massive gaseous planet and a small brown dwarf.
It belongs in the youngest group of stars in the solar neighborhood, known collectively as the TW Hydrae association, which contains about two dozen 10 million-year-old stars, all moving together through space.
Using data from NASA’s Wide-field Infrared Survey Explorer (WISE) and ground-based telescopes, 2MASS J1119-1137 was identified by its unique light signature using a combination of optical and infrared images from large-area surveys of the sky.
“We identified 2MASS J1119-1137 by its highly unusual light signature,” said team member Kendra Kellogg, from the University of Western Ontario, Canada.
“It emits much more light in the infrared part of the spectrum than it would be expected to if it had already aged and cooled.”
2MASS J1119-1137. Image credit: David Rodriguez / Jacqueline Faherty / Jonathan Gagné / Stanimir Metchev.
Being only 95 light-years away, 2MASS J1119-1137 narrowly misses the crown for being the brightest free-floating planet analog.
That is held by another object known as PSO J318.5-22, discovered in 2013. However, at an age of 23 million years, PSO J318.5-22 is more than twice the age of 2MASS J1119-1137, and is therefore more massive.
“Discovering free-floating planet analogs like 2MASS J1119-1137 and PSO J318.5-22 offers a great opportunity to study the nature of giant planets outside the Solar System,” Kellogg said.
“Free-floating planet candidates are much easier to scrutinize than planets orbiting around other stars.”
“Objects like 2MASS J1119-1137 are drifting in space all alone and our observations are not overwhelmed by the brightness of a host star next door.”
The results were published this week in the Astrophysical Journal Letters (arXiv.org preprint).
_____
Kendra Kellogg et al. 2016. The Nearest Isolated Member of the TW Hydrae Association is a Giant Planet Analog. ApJ 821, L15; doi: 10.3847/2041-8205/821/1/L15
