Distance = 3.64 parsecs = 11.9 light-years Position (J2000): Right Ascension = 01 h 44.1 m = 26.04 d Declination = -15 d 56 m = - 15.94 d Galatic Longitude = 173.19 d Galactic Latitude = -73.43 d Apparent Magnitude = 3.49If you wish to learn more about celestial coordinates, consult any of the various amateur-astronomer guides available, both in print and online.
Tau Ceti, though one of the closest stars to the Sun, is one of the (apparently) dimmer stars that are visible without the aid of a telescope. It is in the constellation Cetus, of course, and it may be difficult to see from places as far north as Scandinavia.
Tau Ceti is actually a rather Sunlike star, though somewhat smaller and cooler. Since it has no observable companions, I have had to estimate its mass with the relationship (luminosity) ~ (mass)^4, which is approximately true for main-sequence stars like the Sun and Tau Ceti. The surface temperature I estimated with the assumption that the central temperature was independent of mass, which is approximately true. Finally, I calculate the distance and period of a planet that receives the same amount of light that the Earth does.
| (quantity) | The Sun | Tau Ceti | (unit) |
|---|---|---|---|
| Absolute Magnitude | |||
| Luminosity | (solar units) | ||
| Mass | (solar units) | ||
| Spectral Type | G2V | G8Vp | |
| Surface Temperature | 5800 | 5500 | kelvins |
| Earth Distance | 1.00 | 0.81 | AU's |
| Earth Period | 1.00 | 0.77 | Earth years |
The year becomes 9 Earth months.
There is the interesting question of what the sky would look like from Tau Ceti. In The Cosmic Connection, Carl Sagan gave a picture of the sky from Tau Ceti; the Sun was a somewhat dim star (magnitude 2.54) in the constellation Ophiuchus. Most of the star positions did not change that much, however, due to Tau Ceti's relative closeness
Also, the "G4 Sunbathing" completion terminal message states that it will take 92 years for the radio-broadcast warning message to reach the earth. That is incorrect -- it will be only 12 years for the message to arrive.
The distance to it is much more difficult to measure than the distance to (for example) Tau Ceti, but it is about 8 kiloparsecs or 26,000 light-years. This is much less than the 500,000 light-years stated in Marathon 2.
In the core itself, the stars will be very closely packed. Finding precise estimates has been rather difficult for me, but I estimate that the average separation of the stars there to be a tenth or less that in the Solar neighborhood -- 0.1 parsecs or 0.3 light-years.
Durandal had examined somewhere around 7000 stars before finding Lh'owon; it is possible to estimate how far the Boomer had traveled between those stars by treating Lh'owon's distance from the Galactic center as comparable to the size of the region of stars examined. Since that region would have linear dimensions of about 20 star separations, it would seem that Durandal traveled about 5 light-years from star to star, or a total of 35,000 light-years -- a distance at least as great as the distance from Tau Ceti! Durandal is likely to have been rather selective, since the average separation of stars in the Galactic core is about 0.3 light-years or less -- implying that he had examined only one in 5000 stars. That would not be surprising, however, if he had confined himself to all the more Sunlike main-sequence stars (spectral class G), and omitted the majority of stars, which are M dwarfs. But that would mean that Lh'owon does not orbit an especially dim star, however.
Yet if most of those 17 years were spent examining those stars to see if Lh'owon is present, then it would take about a day per star.
But let's consider what would happen if the Boomer had taken 17 years to reach the Galactic core. From the above distance to there, its cruising speed works out to be 1500 c.
At this rate, if Durandal had wanted to return to the Solar System, he would have taken only 3 days to do so. Three hundred years going, three days returning -- what a trip!
However, doing so would have been a slight detour, since the angle between the Sun and the Galactic core from Tau Ceti is about 76 degrees.
On the way, however, is the bright red supergiant Antares, which is about 200 parsecs (600 light-years) away from the Sun, and which makes an angle of 17 degrees from the Galactic core, again from the Sun (the figures from Tau Ceti will not be much different). This means that after traveling about 5 months, the Boomer will make its closest approach to Antares -- 54 parsecs (180 light-years), and Antares will appear as bright (apparent magnitude -1.6) as Sirius does from the Solar System. (Note in passing: "red" and "orange" stars look yellowish to me, "yellow" stars look white to me, and "white" stars look bluish to me.)
And from Lh'owon to the Galactic center would take only 24 days.
Adding the estimated Galactic-core travels to the total distance yields a travel distance of 61,000 light-years, yielding a cruising speed of 3600 c. Scaling the numbers appropriately, this yields a little over one day from Tau Ceti to the Sun, passing Antares in 2 months, and going from Lh'owon to the Galactic center in only 10 days.
And if Durandal had taken only a year to do all his traveling, however, the Boomer would have had a cruising speed of 60,000 c, yielding only 2 hours from Tau Ceti to the Sun, passing Antares in 4 days, and going from Lh'owon to the Galactic center in 14 hours.
Isn't FTL travel fun? :-)
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