WISE 0855-0714

WISE 0855-0714 (full designation: WISE J085510.83-071442.5) is a sub-brown dwarf located around 7.27 light years (2.23 parsecs) away from Earth in the constellation Hydra. It was discovered in April 2014 by astronomer Kevin Luhman, using data from the Wide-field Infrared Survey Explorer (WISE). The object has a temperature of roughly 225 K to 260 K (-48 °C to -13 °C; -55 to -8 °F), which makes it the coldest object of its type found in interstellar space. It has a parallax of 449 mas, making it the fourth-closest known extrasolar planet to the Sun.

As of 2019, WISE 0855-0714 has the third-highest proper motion (8118 mas/yr), after Barnard's Star (10,300 mas/yr) and Kapteyn's Star (8600 mas/yr).

Characteristics[]

Observations[]

The object was first discovered in March 2013. Follow-up observations by the Spitzer Space Telescope and the Gemini North telescope were later taken. The name "WISE J085510.83-071442.5" includes coordinates and indicates that the object is located in the constellation of Hydra.

Distance and proper motion[]

Based on direct observations it can be calculated that WISE 0855-0714 has a large parallax, which specifically relates to its distance from the Solar System. This results in a distance of around 7.27 ± 0.13 light years. The distance has a slight margin of error due to the strength of the parallax effect and clarity of observations. WISE 0855-0714's proper motion across the sky is also directly observed over time, causing it to stand out in the observations, but the proper motion is itself a combination of its speed in the galactic neighborhood relative to the Solar System as well as its proximity to the Solar System. If it were moving exactly as fast but farther away, if it were moving more slowly but closer, or if it were moving more quickly near to the Sun but moving at a high angle towards or away from the Sun, it would have a smaller proper motion.

Spectrometry[]

Its luminosity in different bands of thermal infrared in combination with its absolute magnitude - because of its known distance - was used to place it in context of different models; the best characterization of its brightness was in the W2 band of 4.6 μm at an apparent magnitude of 13.89 ± 0.05, though it was brighter into the deeper infrared. Infrared images taken with the Magellan Baade Telescope suggest evidence of water clouds.

Classification and temperature[]

Based on models of brown dwarfs, WISE 0855−0714's estimated mass is 3 to 10 Jupiter masses. This mass is in the range of either a sub-brown dwarf or another planetary-mass object.

The International Astronomical Union considers any object with a mass above 13 Jupiter masses capable of fusing deuterium to be a brown dwarf as of 2003. A lighter object and one orbiting another object is considered a planet. So far, this WISE object is alone, although based on these definitions it could be considered a rogue planet. A similar case was first observed in 2004 when another sub-brown dwarf named Cha 110913-773444 was found without a parent star.

Combining its luminosity, distance and mass, it is estimated that this object is the coldest known brown dwarf to date, with a modeled temperataure of around 225 to 260 K (-48 °C to -13 °C; -55 to -8 °F), based on different models.