Space is littered with vague and bizarre objects and a team of astronomers has found two more -- a pair of objects that started out as stars but were so harshly cannibalized by companion stars that they now resemble "failed stars" called brown dwarfs.

Astronomers discovered these pseudo brown dwarfs using the U.K. Infrared Telescope (UKIRT) in Hawaii. But unlike brown dwarfs, which never burn the way stars do, these objects turn out to be remnants of ordinary stars, whittled down over billions of years to planet-sized objects, the likes of which scientists had never seen before.

"These objects have been losing mass, rotating very fast and maybe started with non-solar compositions, [are very old] and might be more-or-less remnant cores of their previous selves," said Steve B. Howell, head of the Astrophysics Group at the Planetary Science Institute in Tucson, Arizona.

The results are set for publication in Astrophysical Journal Letters.

For decades, astronomers have predicted that stars or substellar objects of this kind exist in binary star systems. Working with David Ciardi of the University of Florida and UKIRT staff scientists Chris Davis and Paul Hirst, Howell found the first direct evidence of the objects by taking infrared spectra with an instrument on the UKIRT of two variable binary star systems: LL Andromedae and EF Eridani.

In each case, the smaller objects have had their mass slowly sucked away over a vast period of time, each by an adjacent white dwarf -- stars like our Sun, only dimmer and much more dense.

To get their results, the observers took advantage of periods when the flow of material between the two stars in these binary systems temporarily stopped. At these quiescent times, UKIRT distinguished the radiation coming from the cool donor star or object.

In the case of LL Andromedae, the astronomers detected methane at a certain wavelength, showing that the donor object's temperature is around 1,300 degrees Kelvin (1,832 degrees Fahrenheit; 1,027 degrees Celsius), similar to a "T-type" methane brown dwarf.

In EF Eridani, the donor object is a little warmer -- about 1,650 degrees Kelvin (2,510 degrees F; 1,377 degrees C), similar to an 'L-type' brown dwarf. According to theory, the estimated mass of these cool objects is about 40 times the mass of Jupiter.

Assuming that they give out about the same amount of radiation as more familiar young brown dwarfs, Howell estimates that both LL Andromedae and EF Eridani are between about 100 and 130 light years away -- virtually neighbors of the solar system.

Young brown dwarfs are now known to exist in the hundreds in the Sun's neighborhood. Their surface temperatures are less than about 3,500 degrees K (5,840 degrees F; 3,200 degrees C). As the surface of a brown dwarf cools below 1,500 degrees K (2,240 degrees F; 1,227 degrees C), a dramatic chemical change takes place: large amounts of methane form, considerably altering its appearance. Methane, or 'T-type,' brown dwarfs are the coolest objects detected so far.

Howell described the new objects:

"Imagine the Earth is a white dwarf star, which is about the same size as the Earth, and that Jupiter is where the Moon is, orbiting around Earth every 80 minutes."

These newly discovered objects are probably about 8 billion years old -- as old as the Milky Way Galaxy itself. Though as cool as brown dwarfs, and similar to them in size and mass, Howell emphasizes that their structure and composition is likely to be different, and is not yet known.

The finding also bears on the hot topic of extrasolar planets -- planets beyond our solar system, some of which are Jupiter-sized but have been found as close to their parent stars as Mercury is to our Sun. That proximity causes some of the extrasolars to behave strangely, puffing up to become "bloated" as a possible result of receiving so much light from their parent star -- just like a hydrogen balloon expands when placed next to a light bulb.

So the new objects provide a nice "natural laboratory," Kulkarni said, for studying the effects of proximity between a star and a subordinate, planet-sized object.

"The question is what does receiving so much light do to this extrasolar planet?" he said. "There is so much interest in extrasolar planets and we'd like to understand what happens to planets that are so close to a star."

The substellar objects are much easier to study because they are next to "puny white dwarfs," Kulkarni said, whereas extrasolar planets are hidden by the glare of their parent stars.

As time goes on, the pulsar "fries away" the companion such that, in one reported case, it had only the mass of 20 Jupiters.

So it seems that cosmic sibling rivalries repeat themselves in various forms throughout the universe.