Brown Dwarfs, Poorly Understood, Poorly Named

A cluster of nearly one thousand newly formed stars is captured in this infrared photograph as it emerges from the gaseous womb from which is was recently born. This extremely young cluster contains the largest known population of objects known as Brown Dwarfs. These are among the faintest sources present in the image.

07 June 2001

What's in a name? Sometimes, not much.

At a gathering in Germany this April of astronomers who study how planets and stars form, a poll was taken to determine whether brown dwarfs needed a new name.

The poll, however informal, represents the scientific community's acknowledgement that brown dwarfs exist in a gray area of definitions. They are cool, dim, but massive objects that so far do a lousy job of bridging our gap in understanding between planets and stars.

"Planetars" was suggested, as was "substellar objects" and host of other names.

Moderate debate ensued. No consensus was reached.

But with today's announcement that a significant number of brown dwarfs have protoplanetary disks around them, and hence must have formed just like stars do, the name "brown dwarf" now seems even less equipped to describe the objects.

Perhaps what brown dwarfs need is a real name, a single word, something memorable. Think planets, stars, comets, asteroids. Catchy names, all.

Charles J. Lada of the Smithsonian Astrophysical Observatory argues that "substellar objects" would now be the most apt moniker.

Prodded to consider that perhaps "substellar objects" wasn't exactly a catch term, Lada scratched his chin, tried to come up with something better, then decided that there was little chance the textbooks would be rewritten anyway.

Then he pointed out that this is all largely a semantic argument. Whatever we call brown dwarfs, they are still just stars that didn't make the grade.

And Nature, for its part, doesn't give a hoot.

"Nature doesn't see a difference between a brown dwarf and a star when it creates them," said August A. Muench of the University of Florida. The disk finding around brown dwarfs is the centerpiece of his doctoral dissertation.

But it sure makes enigmas out of the littler ones.