Thursday, June 28, 2007

Welcome to Our Stellar Neighborhood

Our Stellar Neighborhood is an ongoing project aimed at providing accurate and useful information to science fiction writers about stars in the Local Bubble. It also can be used by scientists and astronomy buffs, though the data isn't always the most relevant for them.

The site arranges the stars in order of distance from Earth. Of course, there is some controversy and uncertainty to some of those stars' actual distances, so most of the light year measurements given are simply averages.

Each star entry contains the following information, when available (note that this is a work in progress):
g Star type - The spectral type given follows the Harvard spectral classification system and when known adds the Yerkes spectral classification.
g Distance from Earth - Measurements are in light years.
g Star Service number - This is an irrelevant entry to everyone except me; the number identifies the star system in my Star Service science fiction series.
g Age - This gives the estimated age of the star, relevant for determining habitability. The younger the star, the less likely that Earth-like life has evolved; the older the star, the greater the chance that Earth-like life has vanished, particularly if it's a red giant or white dwarf. Indeed, though our own sun has a good 5-7 billion years left of existence, in another 500 million years when it brightens, the Earth may become uninhabitable as the oceans boil off.
g Diameter/Mass/Temperature - This data will help determine circumstellar habitable zones for Earth-like planets. When the star is more massive and hotter than the sun, the habitable zone is farther out than in our solar system. When it's smaller and cooler, the habitable zone is closer to the star. The measurements typically are given as a percentage of our sun, with Sol equalling 100%; therefore, 50% means the star is half as massive as the sun while 150% means it's 50% more massive.
g Brightness - A star's luminosity also will help determine circumstellar habitable zones for Earth-like planets. The brigher the star, the farther out the habitable zone must be for a planet to receive the degree of light that Earth does from the sun; the dimmer the star, the closer in the planet must be. The measurements typically are given as a percentage of our sun, with Sol equalling 100%.
g Metallicity - This refers to the proportion of a star's matter made up of chemical elements other than hydrogen and helium. Metallicity also can determine if an Earth-like planet might exist in that star system. The measurements typically are given as a percentage of our sun, with Sol equalling 100%. The closer the percentage to the sun's metallicity, the better the chance that terrestrial planets will exist. If the metallicity is greater than the sun's, that's always good for the formation of terrestrial planets.
g Comparison to Sol - These are links to graphics showing the relative sizes and colors of the star and our sun.
g Picture of star - These are links to photographs of the star. When copyrights allow, I'll post a picture of the star on its page's upper right corner.
g Star system features - This data provides interesting facts about the star system that might be mentioned in a story to increase its verismilitude.
g Known planets - This lists any exoworlds that we've definitely discovered or that our current research predicts should exist in the star system.
g Habitable zone - My favorite section! It lists, when known, the distance from the star (generally in AUs) that an Earth-like planet could exist. It also provides any information about what that planet might be like. The tag "habitable" appears for stars that are excellent candidates for circumstellar habitable zones for Earth-like planets.
g Orbital map - These are links to graphics visually showing how a known exoworld orbits the star or giving the star system's circumstellar habitable zones for Earth-like planets.
g View from the star - These are links to graphics showing how stars would appear in the night sky of a planet orbiting the star.
g Nearby stars - This lists all stars within 10 light years of this star. If the neighboring star is habitable (generally G-, F- or K-type), that information is given. Sometimes neighboring stars farther than 10 light years are listed, especially if the page's star is "geographically" at the center of several potentially habitable systems.
g Map locating star system - These are links to star maps that look down upon the galactic plane, typically with Sol at the map's center.
g Location in Earth sky - This describes where the star appears in our night sky. Not all of the stars are visible with the naked eye or even an amatuer telescope, but their location still is provided; usually a note is given indicating it's not visible with the naked eye.
g Other names - Unfortunately, the number of competing star catalogues means many stars have more than one name. Generally the popular name for the star is listed as its page name with other names listed in this section. All of these names come from actual star catalogues used by astronomers.
g Sci-fi mentions - Many of these stars appear in science fiction novels, short stories, movies, television shows and video games. Knowing how other authors have represented the star in fiction sometimes is useful and certainly entertaining. Warning: The lists in this section are far from complete.

Of course, this site contains a geocentric bias - it focuses on data that would point toward Earth-like planets containing Earth-like lifeforms. Other habitable zones almost certainly exist, particularly the moons around gas giants. In addition, alien life probably is far more different that ours and I'd bet has evolved in all kinds of solar and planetary environments so that their geocentric definition of a habitable zone wouldn't allow for us on Earth to exist. But science fiction stories involving space travel often are about places that humans can colonize or at least take off their spacesuits to interact with similar carbon-based, oxygen-breathing aliens, hence this site's focus.

A couple of other useful references I offer for science fiction writers are two online sites. Alien Life is a blog that provides the latest news and speculations in astrobiology. Inventing Reality is about writing science fiction.

Should you find errors on this site or have additional information that would be useful, please contact me.

This sight is dedicated to my son Kieran, who as a toddler never failed to point out to me the moon and the stars when they were out.

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