Tiny Brown Dwarf's Disk May Form Miniature Solar System

February 9, 2005

Using the Spitzer Space Telescope, a team of astronomers led by Kevin Luhman (Harvard-Smithsonian Center for Astrophysics) has discovered a protoplanetary disk around a surprisingly low-mass brown dwarf. This remarkable finding raises the possibility of planet formation around objects that themselves have planetary masses. Moreover, the presence of a disk suggests that terrestrial planets could form and thrive orbiting an object too small to shine via nuclear fusion.

"It's an exciting possibility-one that hasn't been explored extensively because this is the first evidence for the building blocks of planets around such a small object," said Luhman.

The team's findings were presented today in a press conference at the Planet Formation and Detection meeting in Aspen, Colorado, and will be published in the Feb. 10th issue of The Astrophysical Journal Letters.

The brown dwarf in question, OTS 44, is located approximately 500 light-years away in the southern constellation Chamaeleon. OTS 44 weighs in at around 15 Jupiter masses, placing it near the dividing line between brown dwarfs (generally defined as objects of 15-70 Jupiter masses) and planets. At a temperature of 3,600° F (2300 Kelvin), OTS 44 is the coolest and least massive brown dwarf known to have a circumstellar disk.

Although the team cannot measure the total mass of the disk, it likely contains enough matter to make one small gas giant or several Earth-sized planets. "This brown dwarf and its disk could eventually evolve into a miniature version of our solar system," said Luhman.

Due to the brown dwarf's low temperature, an Earth-sized world would have to orbit much closer to the brown dwarf than the Earth from the Sun in order to be as warm as Earth. Theorists estimate that liquid water could exist on the surface of a planet about 1 to 4 million miles from the brown dwarf. The disk of OTS 44 extends beyond both sides of this "habitable zone."

Without nuclear fusion to sustain it, the brown dwarf will gradually cool and dim. If an Earth-sized world forms near the brown dwarf, it will be scorching at first, then grow cooler and more hospitable over time. Since the brown dwarf cools more slowly as it gets older, such a planet could remain in the habitable zone for an extended time, raising the intriguing possibility that life might evolve.

"That is pure speculation, of course. But finding a circumstellar disk around such a small brown dwarf certainly widens the possibilities for planet formation," said Luhman.

The researchers plan to search for similar disks around other nearby brown dwarfs. Spitzer revealed the disk of OTS 44 in only 20 seconds of observing time. Further searches may locate similar disks around even smaller central objects of 10 Jupiter masses or less.

The team detected OTS 44's circumstellar disk using Spitzer's Infrared Array Camera, or IRAC. IRAC data showed an excess of infrared emission at long wavelengths-the signature of a dusty disk that absorbs radiation from the brown dwarf, heats up, and re-radiates the energy in the infrared.

Explore further: Brown dwarfs, stars share formation process, new study indicates

Related Stories

Why don't we send probes "up" in the solar system?

July 10, 2015

Dammit, science people! Why are you always firing probes "outwards"? Then they have to go past all this stuff, like planets and asteroids and crap to escape the solar system. Don't you realize that if we want to see what's ...

What is the newest planet?

July 7, 2015

With astronomers discovering new planets and other celestial objects all the time, you may be wondering what the newest planet to be discovered is. Well, that depends on your frame of reference. If we are talking about our ...

Can planets be rejuvenated around dead stars?

June 26, 2015

For a planet, this would be like a day at the spa. After years of growing old, a massive planet could, in theory, brighten up with a radiant, youthful glow. Rejuvenated planets, as they are nicknamed, are only hypothetical. ...

A conversation with astronomer Dimitri Mawet

May 18, 2015

Associate Professor of Astronomy Dimitri Mawet has joined Caltech from the Paranal Observatory in Chile, where he was a staff astronomer for the Very Large Telescope. After earning his PhD at the University of Liège, Belgium, ...

Recommended for you

Most EU nations seek to bar GM crops

October 4, 2015

Nineteen of the 28 EU member states have applied to keep genetically modified crops out of all or part of their territory, the bloc's executive arm said Sunday, the deadline for opting out of new European legislation on GM ...

The dark side of Nobel prizewinning research

October 4, 2015

Think of the Nobel prizes and you think of groundbreaking research bettering mankind, but the awards have also honoured some quite unhumanitarian inventions such as chemical weapons, DDT and lobotomies.

Internet giants race to faster mobile news apps

October 4, 2015

US tech giants are turning to the news in their competition for mobile users, developing new, faster ways to deliver content, but the benefits for struggling media outlets remain unclear.

Fusion reactors 'economically viable' say experts

October 2, 2015

Fusion reactors could become an economically viable means of generating electricity within a few decades, and policy makers should start planning to build them as a replacement for conventional nuclear power stations, according ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.