Most Milky Way Stars Are Single

[phantom power]

Astronomers have long known that massive, bright stars, including stars like the sun, are most often found to be in multiple star systems. This fact led to the notion that most stars in the universe are multiples. However, more recent studies targeted at low-mass stars have found that these fainter objects rarely occur in multiple systems. Astronomers have known for some time that such low-mass stars, also known as red dwarfs or M stars, are considerably more abundant in space than high-mass stars.

(...)

Among very massive stars, known as O- and B-type stars, 80 percent of the systems are thought to be multiple, but these very bright stars are exceedingly rare. Slightly more than half of all the fainter, sun-like stars are multiples. However, only about 25 percent of red dwarf stars have companions. Combined with the fact that about 85 percent of all stars that exist in the Milky Way are red dwarfs, the inescapable conclusion is that upwards of two-thirds of all star systems in the Galaxy consist of single, red dwarf stars.

(...)

Lada's finding implies that planets also may be more abundant than astronomers realized. Planet formation is difficult in binary star systems where gravitational forces disrupt protoplanetary disks. Although a few planets have been found in binaries, they must orbit far from a close binary pair, or hug one member of a wide binary system, in order to survive. Disks around single stars avoid gravitational disruption and therefore are more likely to form planets.

Interestingly, astronomers recently announced the discovery of a rocky planet only five times more massive than Earth. This is the closest to an Earth-size world yet found, and it is in orbit around a single red dwarf star.

http://www.sciencedaily.com/releases/2006/02/060206233911.htm

[benburch]

1. Match.com has a business oppotunity!

:pals:

[htuttle]

2. I'm wondering a couple of things after reading this

I'm wondering if there is any (inverse) correlation between the mass of the star, and the mass of the non-luminous stuff that orbits stars, ie., planets, asteroids, etc... For example, small, lower mass stars might tend to have larger amounts of planetary mass and such, while larger, higher mass stars might tend to have smaller amounts of 'non-star' material in their orbits? I'd think gravity alone might do this.

When a star novas, I've been under the impression that much if not most of the material eventually ends up back in the accretion disk of the new star to form there. Does matter get blown between stars much?

[phantom power]

3. Astronomers seem to be rethinking that too.

The larger the star, the faster it burns. Very large stars last only a few million years. A very very short time, compared to a more modest star like ours. They don't last long enough to form large planets. But apparently, they may have large amounts of non-star material:

The new Spitzer results expand the range of stars that sport disks to include the "extra large." The infrared telescope detected enormous amounts of dust around two positively plump stars, R 66 and R 126, located in the Milky Way's nearest neighbor galaxy, the Large Magellanic Cloud. Called hypergiants, these blazing hot stars are aging descendents of the most massive class of stars, referred to as "O" stars. They are 30 and 70 times the mass of the sun, respectively. If a hypergiant were located at the sun's position in our solar system, all the inner planets, including Earth, would fit comfortably within its circumference.

Astronomers estimate that the stars' disks are also bloated, spreading all the way out to an orbit about 60 times more distant than Pluto's around the sun. The disks are probably loaded with about ten times as much mass as is contained in the Kuiper Belt. Kastner and his colleagues say these dusty structures might represent the first or last steps of the planet-forming process. If the latter, then the disks can be thought of as enlarged versions of our Kuiper Belt.

"These disks may be well-populated with comets and other larger bodies called planetesimals," said Kastner. "They might be thought of as Kuiper Belts on steroids."

http://www.sciencedaily.com/releases/2006/02/060208155436.htm

[phantom power]

4. A red-dwarf star may be the best real estate investment.

They burn much slower than a star like ours. If I recall correctly, they may last upwards of a 100 billion years. A nice warm planet, close in, might support a biosphere for many billions of years.