Sigma Draconis (star)/meta
Notes (2016)[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.
TRAVELLER NOTE:
Prior to the current T5SS Data, CT: AM 06 (Solomani) had listed the world Dingir (SR 1222) with the stellar data K0 V M1 D, making it a prime candidate for the location of Sigma Draconis at the time. If the M1 D component is interpreted as a degenerate dwarf, then it could correspond to the nearby degenerate dwarf LP 44-113 which has spectral classification DQP9 and bears a yellowish-white hue, and lies at just under 1pc distance from Sigma Draconis.
ASTROGRAPHIC NOTE:
Sigma Draconis may have a Uranus-mass planet on a 308-day orbit. Other non-planetary explanations for velocity variations have not yet been ruled out, however.
- Sigma Draconis system:
- * COMPANION (unconfirmed): Sigma Draconis b MASS: ≳12 M⊕ ORBIT: ~ 0.814AU PERIOD: 308 days