Difference between revisions of "Milky Way"
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The [[Milky Way]], home to the [[Solar System]], is one of the densest, most massive spiral galaxies known, and the dominant member of the [[Local Group]] by [[mass]]. While its stellar disc is physically smaller than [[Andromeda]]'s, our home [[galaxy]] has about half again the [[mass]] of its already giant neighbor, at least [http://adsabs.harvard.edu/cgi-bin/bib_query?2000MNRAS.316..929E 1.9 trillion Solar Masses], about a third of which is baryonic, and half of that luminous. This suggests a total stellar population around 600 billion, but could be as high as a few trillion. | The [[Milky Way]], home to the [[Solar System]], is one of the densest, most massive spiral galaxies known, and the dominant member of the [[Local Group]] by [[mass]]. While its stellar disc is physically smaller than [[Andromeda]]'s, our home [[galaxy]] has about half again the [[mass]] of its already giant neighbor, at least [http://adsabs.harvard.edu/cgi-bin/bib_query?2000MNRAS.316..929E 1.9 trillion Solar Masses], about a third of which is baryonic, and half of that luminous. This suggests a total stellar population around 600 billion, but could be as high as a few trillion. | ||
| − | An extremely pronounced bar structure appears to dominate the central region of the [[Milky Way]], suggesting that the [[galaxy]] has yet to encounter a major collision event, though eventually [[Andromeda]] will make such a collision. The central black hole, massing an estimated | + | An extremely pronounced bar structure appears to dominate the central region of the [[Milky Way]], suggesting that the [[galaxy]] has yet to encounter a major collision event, though eventually [[Andromeda]] will make such a collision. The central black hole, massing an estimated 3.4 million solar masses, is exceedingly tiny compared to the expected average of a billion solar masses for a galaxy of such [[mass]]. |
| − | + | == [[Star system]]s == | |
| − | + | * [[61 Cygni]] - a double-star system 11.4 light-years away, with several rocky planets, none bearing significant life. | |
| + | * [[Alpha Centauri]] - not only the closest star system, the only system so far discovered that definitely possessed multicellular life. | ||
| + | * [[Epsilon Eridani]] - a young, metal-poor star about 10.5 light-years distant, and is still undergoing planet formation. | ||
| + | * [[Epsilon Indi]] - a youngish star about 11.8 light-years away, with a pair of [[brown dwarf]]s orbiting at an extreme range. The planets here are considered to be prime material for terraforming. | ||
| + | * [[Procyon]] - a large, yellow sun with a [[white dwarf]] companion, 11.4 light-years away. It is host to a number of scorched, mineral-rich worlds, hopeless for terraforming but some rogue [[artificial sapience]]s hope to make a new civilization there, labeling their banner the [[Procyon Concord]]. | ||
| + | * [[Sirius]] - a very young, but brilliant star about 8.6 light-years away, with a [[white dwarf]] companion. | ||
| + | * [[Solar System]] - host to a few notable worlds and life forms. Now host to the [[Hellskearn]]. | ||
| + | * [[Tau Ceti]] - an ancient, metal-poor system 11.9 light-years distant with many worlds, comets and other bodies formed largely of methane and water. One world, dubbed [[Poseidon]], has no features other than a giant ocean hundreds of miles deep. | ||
| − | {{ | + | {{SS}} |
Revision as of 16:33, 22 March 2007
The Milky Way, home to the Solar System, is one of the densest, most massive spiral galaxies known, and the dominant member of the Local Group by mass. While its stellar disc is physically smaller than Andromeda's, our home galaxy has about half again the mass of its already giant neighbor, at least 1.9 trillion Solar Masses, about a third of which is baryonic, and half of that luminous. This suggests a total stellar population around 600 billion, but could be as high as a few trillion.
An extremely pronounced bar structure appears to dominate the central region of the Milky Way, suggesting that the galaxy has yet to encounter a major collision event, though eventually Andromeda will make such a collision. The central black hole, massing an estimated 3.4 million solar masses, is exceedingly tiny compared to the expected average of a billion solar masses for a galaxy of such mass.
Star systems
- 61 Cygni - a double-star system 11.4 light-years away, with several rocky planets, none bearing significant life.
- Alpha Centauri - not only the closest star system, the only system so far discovered that definitely possessed multicellular life.
- Epsilon Eridani - a young, metal-poor star about 10.5 light-years distant, and is still undergoing planet formation.
- Epsilon Indi - a youngish star about 11.8 light-years away, with a pair of brown dwarfs orbiting at an extreme range. The planets here are considered to be prime material for terraforming.
- Procyon - a large, yellow sun with a white dwarf companion, 11.4 light-years away. It is host to a number of scorched, mineral-rich worlds, hopeless for terraforming but some rogue artificial sapiences hope to make a new civilization there, labeling their banner the Procyon Concord.
- Sirius - a very young, but brilliant star about 8.6 light-years away, with a white dwarf companion.
- Solar System - host to a few notable worlds and life forms. Now host to the Hellskearn.
- Tau Ceti - an ancient, metal-poor system 11.9 light-years distant with many worlds, comets and other bodies formed largely of methane and water. One world, dubbed Poseidon, has no features other than a giant ocean hundreds of miles deep.
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