Surface map of Luhman 16B recreated from VLT observations
Surface map of Luhman 16B recreated from VLT observations
Wide-field view of the sky around the nearby brown dwarf pair
***************************************
Videos
Artist's impression of Luhman 16B recreated from VLT observations
Surface map of Luhman 16B recreated from VLT observations
Zooming in on the nearby brown dwarf Luhman 16B
Flying among the closest stars to the Solar System
ESO’s VLT charts surface of nearest brown dwarf
ESO's Very Large Telescope has been used
to create the first ever map of the weather on the surface of the
nearest brown dwarf to Earth. An international team has made a chart of
the dark and light features on WISE J104915.57-531906.1B, which is
informally known as Luhman 16B and is one of two recently discovered
brown dwarfs forming a pair only six light-years from the Sun. The new
results are being published in the 30 January 2014 issue of the journal
Nature.
Brown dwarfs fill the gap between giant gas planets, such as Jupiter
and Saturn, and faint cool stars. They do not contain enough mass to
initiate nuclear fusion in their cores and can only glow feebly at
infrared wavelengths of light. The first confirmed brown dwarf was only
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 [1]
that lies just six light-years from Earth in the southern constellation
of Vela (The Sail). This pair is the third closest system to the Earth,
after Alpha Centauri and Barnard's Star, but it was only discovered in
early 2013. The fainter component, Luhman 16B, had already been found to
be changing slightly in brightness every few hours as it rotated — a
clue that it might have marked surface features.
Now astronomers have used the power of ESO's Very Large Telescope
(VLT) not just to image these brown dwarfs, but to map out dark and
light features on the surface of Luhman 16B.
Ian Crossfield (Max Planck Institute for Astronomy, Heidelberg,
Germany), the lead author of the new paper, sums up the results: “Previous
observations suggested that brown dwarfs might have mottled surfaces,
but now we can actually map them. Soon, we will be able to watch cloud
patterns form, evolve, and dissipate on this brown dwarf — eventually,
exometeorologists may be able to predict whether a visitor to Luhman 16B
could expect clear or cloudy skies.”
To map the surface the astronomers used a clever technique. They observed the brown dwarfs using
the CRIRES instrument on the VLT.
This allowed them not just to see the changing brightness as Luhman 16B
rotated, but also to see whether dark and light features were moving
away from, or towards the observer. By combining all this information
they could recreate a map of the dark and light patches of the surface.
The atmospheres of brown dwarfs are very similar to those of hot gas
giant exoplanets, so by studying comparatively easy-to-observe brown
dwarfs [2]
astronomers can also learn more about the atmospheres of young, giant
planets — many of which will be found in the near future with the new
SPHERE instrument that will be installed on the VLT in 2014.
Crossfield ends on a personal note: “Our brown dwarf map helps
bring us one step closer to the goal of understanding weather patterns
in other solar systems. From an early age I was brought up to appreciate
the beauty and utility of maps. It's exciting that we're starting to
map objects out beyond the Solar System!”
Notes
[1] This pair was discovered by the
American astronomer Kevin Luhman on images from the WISE infrared survey
satellite. It is formally known as WISE J104915.57-531906.1, but a
shorter form was suggested as being much more convenient. As Luhman had
already discovered fifteen double stars the name Luhman 16 was adopted.
Following the usual conventions for naming double stars, Luhman 16A is
the brighter of the two components, the secondary is named Luhman 16B
and the pair is referred to as Luhman 16AB.
[2] Hot Jupiter exoplanets lie very close to their
parent stars, which are much brighter. This makes it almost impossible
to observe the faint glow from the planet, which is swamped by
starlight. But in the case of brown dwarfs there is nothing to overwhelm
the dim glow from the object itself, so it is much easier to make
sensitive measurements.
More information
This research was presented in a paper, “A
Global Cloud Map of the Nearest Known Brown Dwarf”, by Ian Crossfield et
al. to appear in the journal Nature.
The team is composed of I. J. M. Crossfield (Max Planck Institute for
Astronomy [MPIA], Heidelberg, Germany), B. Biller (MPIA; Institute for
Astronomy, University of Edinburgh, United Kingdom), J. Schlieder
(MPIA), N. R. Deacon (MPIA), M. Bonnefoy (MPIA; IPAG, Grenoble, France),
D. Homeier (CRAL-ENS, Lyon, France), F. Allard (CRAL-ENS), E. Buenzli
(MPIA), Th. Henning (MPIA), W. Brandner (MPIA), B. Goldman (MPIA) and T.
Kopytova (MPIA; International Max-Planck Research School for Astronomy
and Cosmic Physics at the University of Heidelberg, Germany).
ESO is the foremost intergovernmental astronomy organisation in
Europe and the world's most productive ground-based astronomical
observatory by far. It is supported by 15 countries: Austria, Belgium,
Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy,
the Netherlands, Portugal, Spain, Sweden, Switzerland and the United
Kingdom. ESO carries out an ambitious programme focused on the design,
construction and operation of powerful ground-based observing facilities
enabling astronomers to make important scientific discoveries. ESO also
plays a leading role in promoting and organising cooperation in
astronomical research. ESO operates three unique world-class observing
sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO
operates the Very Large Telescope, the world's most advanced
visible-light astronomical observatory and two survey telescopes. VISTA
works in the infrared and is the world's largest survey telescope and
the VLT Survey Telescope is the largest telescope designed to
exclusively survey the skies in visible light. ESO is the European
partner of a revolutionary astronomical telescope ALMA, the largest
astronomical project in existence. ESO is currently planning the
39-metre European Extremely Large optical/near-infrared Telescope, the
E-ELT, which will become “the world's biggest eye on the sky”.
Links
Contacts
Ian Crossfield
Max Planck Institute for Astronomy
Heidelberg, Germany
Tel: +49 6221 528 406
Email: ianc@mpia.de
Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Source: ESO
.jpg)