Red skies discovered on extreme brown dwarf

Feb 06, 2014
An artist’s impression of ULAS J222711-004547. This newly discovered brown dwarf is characterized by an unusually thick layer of clouds, made of mineral dust. These thick clouds give ULAS J222711-004547 its extremely red colour, distinguishing it from “normal” brown dwarfs. Credit: Neil J Cook, Centre for Astrophysics Research, University of Hertfordshire.

(Phys.org) —A peculiar example of a celestial body, known as a brown dwarf, with unusually red skies has been discovered by a team of astronomers from the University of Hertfordshire's Centre for Astrophysics Research. The scientists publish their results in the journal Monthly Notices of the Royal Astronomical Society.

Brown dwarfs straddle the line between stars and planets. They are too big to be considered as planets; yet they do not have sufficient material to fuse hydrogen in their cores to fully develop into stars. They are midway in mass between stars, like our Sun, and giant planets, like Jupiter and Saturn. Sometimes described as failed stars, they do not have an internal source of energy – so they are cold and very faint, and keep on cooling over time.

The brown dwarf, named ULAS J222711-004547, caught the researchers' attention for its extremely red appearance compared to "normal" . Further observations with the VLT (Very Large Telescope) in Chile and the use of an innovative data analysis technique have shown that the reason for its peculiarity is the presence of a very thick layer of clouds in its upper atmosphere.

Federico Marocco, who led the research team from the University of Hertfordshire, said: "These are not the type of clouds that we are used to seeing on Earth. The thick clouds on this particular brown dwarf are mostly made of mineral dust, like enstatite and corundum.

"Not only have we been able to infer their presence, but we have also been able to estimate the size of the dust grains in the clouds."

The size of the dust grains influences the colour of the sky. In a similar way that the old saying of "Red sky at night, shepherd's delight. Red sky in the morning, shepherd's warning" is used at sunrise and sunset to indicate the changing weather, a red sky on the brown dwarf suggests an atmosphere loaded with dust and moisture particles. If our morning skies are red, it is because clear skies to the east permit the sun to light the undersides of moisture-bearing clouds coming in from the west. Conversely, in order to see red clouds in the evening, sunlight must have a clear path from the west in order to illuminate moisture-bearing clouds moving off to the east. However, the recently discovered brown dwarf ULAS J222711-004547 has a very different atmosphere where the sky is always red.

The giant planets of the Solar System, like Jupiter and Saturn, show various cloud layers including ammonia and hydrogen sulphide as well as water vapour. The atmosphere observed in this particular brown dwarf is hotter - with water vapour, methane and probably some ammonia but, unusually, it is dominated by clay-sized mineral particles.

Getting a good understanding of how such an extreme atmosphere works will help us to better understand the range of atmospheres that can exist.

Dr Avril Day-Jones, from the University of Hertfordshire's Centre for Astrophysics Research, who contributed to the discovery and analysis said: "Being one of the reddest brown dwarfs ever observed, ULAS J222711-004547 makes an ideal target for multiple observations to understand how the weather is in such an extreme atmosphere."

"By studying the composition and variability in luminosity and colours of objects like this, we can understand how the weather works on brown dwarfs and how it links to other ."

Explore further: Stormy stars? Spitzer probes weather on brown dwarfs

More information: "The extremely red L dwarf ULAS J222711−004547 - dominated by dust." F. Marocco, A. C. Day-Jones, P. W. Lucas, H. R. A. Jones, R. L. Smart, Z. H. Zhang, J. I. Gomes, B. Burningham, D. J. Pinfield, R. Raddi, L. Smith. Monthly Notices of the Royal Astronomical Society. Preprint: http://arxiv.org/abs/1401.0420

Related Stories

Stormy stars? Spitzer probes weather on brown dwarfs

Jan 07, 2014

(Phys.org) —Swirling, stormy clouds may be ever-present on cool celestial orbs called brown dwarfs. New observations from NASA's Spitzer Space Telescope suggest that most brown dwarfs are roiling with one ...

First weather map of brown dwarf

Jan 29, 2014

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 ...

Newly discovered celestial object defies categories

Jan 08, 2014

An object discovered by astrophysicists at the University of Toronto (U of T) nearly 500 light years away from the Sun may challenge traditional understandings about how planets and stars form.

Astronomers find extreme weather on an alien world

Sep 12, 2011

(PhysOrg.com) -- A University of Toronto-led team of astronomers has observed extreme brightness changes on a nearby brown dwarf that may indicate a storm grander than any seen yet on a planet. Because old ...

Super cold brown dwarf or is it a planet?

Mar 23, 2011

(PhysOrg.com) -- In a month that has already announced the discovery of a brown dwarf 75 light-years from Earth, NASA’s infrared Spitzer Space Telescope has found what could prove to be an even cooler, ...

Recommended for you

Three views of the North America Nebula

27 minutes ago

A perfect set of astrophotos for #WideAngleWednesday! Here are not one but three views of the North America Nebula taken by Terry Hancock. Terry said this is his widest view yet of this region. Also known as ...

The origins of local planetary orbits

Oct 01, 2014

A plutino is an asteroid-sized body that orbits the Sun in a 2:3 resonance with Neptune. They are named after Pluto, which also orbits the Sun twice for every three orbits of Neptune. It is thought that Pluto ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

GSwift7
5 / 5 (2) Feb 06, 2014
...Red sky in the morning, shepherd's warning...


Yeah, so they explain how that works. Then this:

However, the recently discovered brown dwarf ULAS J222711-004547 has a very different atmosphere where the sky is always red


yeah, so it's nothing like that other stuff we were just telling you about. lol.

I know, it's just a short press release, and it probably made more sense in its original context, which was probably a longer statement. That's still funny the way they wrote it here though.