Helix Nebula/meta
Notes (2019)[edit]
NOTE CONCERNING POSITIONS OF STARS AND CELESTIAL OBJECTS :
When comparing real-astronomical celestial object positions to the Traveller Map of Charted Space, it needs to be observed that the axes of the Charted Space Map appear to be tilted about 45o counter-clockwise from the correct position (i.e. "true" Coreward (in the direction of Sagittarius A*) actually lies in the general direction of the Lesser Rift; "true" Rimward falls directly on a bearing towards the star Capella). If one makes that adjustment, about 70% of the named stars and celestial objects will fall roughly along their correct bearing. However, there are some exceptions in which the star in question lies in roughly the correct position relative to the Charted Space Map without the need to rotate the coordinate axes.
Thus, if one takes a straight-edge and draws a line thru Sol/Terra and Capella, astronomically speaking you have drawn a precise Coreward-Rimward axis-line.
In general, if one is assigning the position of a Real-Universe star or celestial object to a Traveller Map hex, it should be acceptable if:
- 1) The object's longitude angle (θ) is within a 45o bearing-arc between the "true" coordinate axes and the Traveller Charted Space Map coordinate axes, and
- 2) The object's assigned distance from Terra on the hexmap falls somewhere between its true distance R in parsecs, and its 2D-projection onto the flat map as seen from above, found by Dproj = {R * cos(ɸ)}, where (ɸ) is the latitude angle. If desired, the distance above/below the plane can be determined by Z = {R * sin(ɸ)}.
- Please also see the entry: Miller Projection (Astronavigation) excerpted from Journal of the Travellers' Aid Society volume 7 (Mongoose Publishing, 2023), p. 71-80 by Dalton Calford
NOTE CONCERNING SPECTRAL CLASS & HUE:
Spectral classification is an indication of the temperature of the stellar surface and originated in the typical chemical composition observed (primarily the brightness/dimness of hydrogen lines in the emission spectrum: from "A" (strongest) to "O" (weakest) before the temperature/chemical relationship was understood). The O,B,A,F,G,K,M "color" classification is traditional, and based on observation thru earth's specific atmosphere, not actual appearance in vacuum. Truly "pinkish-red" to "cherry-red" stars would be a few late M-type stars and L-Type thru T-Type Brown Dwarfs, as well as CR, CN and S type giant stars "Carbon Stars" which are a ruby-red coloration due to chemical composition oddities.
The documentation for the Helix Nebula included with the Original Paranoia Press published material (1981 Booklet) noted the following:
- "A gas cloud thrown off approximately 99,500 PI by the primary star in location 0407 in the Helix Subsector . . . Several points of coalescence within the cloud are thought to have produced protostars . . ."
The documentation for the Helix Nebula included with the Paranoia Press 1991 Updates reads as follows:
- "The most significant astrographic feature is the Helix Nebula, a circular veil of interstellar gas surrounding a group of seventeen hot, young stars in the spinward-rimward corner of the sector."
This is in actuality factually in error. The cloud was intially thrown off closer to 14,500 PI, with expansion of the entire structure from about 9,500 PI. The stellar remnant at the center of the Helix Nebula is a "Degenerate Dwarf" (aka "White Dwarf") that produced what is known as a "Planetary Nebula" as it ended its life as a thermonuclear-burning star, increasingly heating its outer layers during its red-giant phase as its core contracted and increased in temperature, so that its outer envelope of gases eventually became gravitationally unbound and drifted away, leaving behind the stellar core remnant. This type of nebula is quite small in mass and size and dissipates rather rapidly over astronomical timescales. It is entirely different from the extremely large and massive molecular H2 cloud nebular regions in the galaxy that give rise to star formation due to gravitational instability.
Like many Planetary Nebulae, the Helix Nebula is known to contain Cometary knots in its main ring, which are large knots of denser nebulosity within the expanding gases. It is likely that these were mistaken for protostars by the original authors.