Lonely Dwarfs


Luhman 16AB is a double star system composed of two brown dwarfs. It’s only about six light-years away, and is the third closest stellar system to Earth—after the triple star system Alpha Centauri and Barnard’s Star. Because the brown dwarfs are so dim, Luhman 16AB was only discovered in 2013.

This series of dots with varying spacings between them in the image above shows the slow waltz of the two brown dwarfs. It’s a composite of 12 images made over the course of three years by the Hubble Space Telescope. Using high-precision astrometry, a team of astronomers tracked the two components of the system as they moved both across the sky and around each other.

The brown dwarfs, Luhman 16A and Luhman 16B, orbit each other at a distance of only about 500,000,000 km, roughly three times the distance between the Earth and the Sun. Observations of the system require high resolution. The astronomers using Hubble to study Luhman 16AB were not only interested in the waltz of the two stars as they orbited each other but also were also searching for a third, invisible partner. Earlier ground-based observation suggested the presence of an exoplanet in the system, but the Hubble data showed that the two dwarfs are indeed dancing alone, unperturbed by a massive planetary companion.

Image Credit: NASA / ESA

A Pair of Lonely Dwarfs


Luhman 16AB is a double star system composed of two brown dwarfs. It’s only about six light-years away, and is the third closest stellar system to Earth—after the triple star system Alpha Centauri and Barnard’s Star. Because the brown dwarfs are so dim, Luhman 16AB was only discovered in 2013.

This series of dots with varying spacings between them in the image above shows the slow waltz of the two brown dwarfs. It’s a composite of 12 images made over the course of three years by the Hubble Space Telescope. Using high-precision astrometry, a team of astronomers tracked the two components of the system as they moved both across the sky and around each other.

The brown dwarfs, Luhman 16A and Luhman 16B, orbit each other at a distance of only about 500,000,000 km, roughly three times the distance between the Earth and the Sun. Observations of the system require high resolution. The astronomers using Hubble to study Luhman 16AB were not only interested in the waltz of the two starss as they orbited each other but also were also searching for a third, invisible partner. Earlier ground-based observation suggested the presence of an exoplanet in the system, but the Hubble data showed that the two dwarfs are indeed dancing alone, unperturbed by a massive planetary companion.

Image Credit: NASA / ESA

It’s Snowing Iron


Surface map of Luhman 16B recreated from VLT observationsBrown drawfs are failed stars. They fill the gap between giant gas planets, such as Jupiter and Saturn, and faint cool stars. They do n’t contain enough mass to initiate nuclear fusion in their cores, so they only glow feebly at infrared wavelengths. The first confirmed brown dwarf was found twenty years ago and only a few hundred of these elusive objects are known. The closest brown dwarfs to the Solar System form a pair called Luhman 16AB about 6.6 light-years from Earth in the southern constellation of Vela (The Sail). This pair is the third closest star system to the Earth, after Alpha Centauri and Barnard’s Star. The fainter brown dwarf Luhman 16B changes slightly in brightness every few hours as it rotates—a clue that it might have surface features.

It turns out that the markings are clouds of silicate rock and iron particles kept aloft by turbulence in the atmosphere. It snows iron on Luhman 16B.

The images above are from IR data of Luhman 16B gathered using the ESO’s Very Large Telescope.

Image Credit: ESO

Meet the New Neighbors


brown_dwarfsWISE J104915.57-531906 is at the center of the main image, which was taken by the  Wide-field Infrared Survey Explorer (WISE). This is the closest star system discovered since 1916, and the third closest to our sun. It is 6.5 light-years away. At first, the light appeared to be from a single object, but a sharper image from Gemini Observatory in Chile revealed that it was from a pair of cool star-like bodies called brown dwarfs.

The pair is only slightly farther away than the second-closest star, Barnard’s star, which was found 6 light-years away in 1916. The closest star system consists of: Alpha Centauri, found in 1839 at 4.4 light-years away, and the fainter Proxima Centauri, discovered in 1917 at 4.2 light-years.

Since WISE J104915.57-531906 is only 6.5 light-years away Earth’s television transmissions from 2006 are now arriving there, and viewers there are still watching the first season of the Tenth Doctor with David Tennant.

Image Credit: NASA