Traveller Needs Astronomy

Since it's foundation in 1977, Traveller has attempted to be the pre-eminent game for reality-based Science Fiction role-playing. It had succeeded quite nicely in that role for a long time. However, some cracks had started to form, which the last edition (TNE) had failed to fix, in the astronomical data that was the description of the underlying universe for the game's setting. Now that the designer of the original game, and some of the founders of the original version are reissuing the game with a new version, some notes are in order.

Marc Miller has said, The game system rules will be consolidated based on the original Classic Traveller rules (revised in light of 20 years of role-playing experience).

Since Traveller is heavily anchored in Science Fiction Adventure in the Far Future, and the future setting is still in the proximity of Earth (Terra/Solomani Rim 1827), attention to correct detail with known Astronomical information should be adhered too. Some of the original astronomical information used as a basis for the game, is now known to be out of date.

Much of the content of this page is from discussions I (Leroy W.L.Guatney) have initiated on the HIWG mailing list. Feel free to approach any of us with comments and feedback.

I am not attempting to Flame, the game, its producers, or anyone that is working hard on the subject. I am merely attempting to generate an interest in the subject of making Traveller the best game possible. I would be happy to have any assistance making that known to the Travelling public.

An Update:

I have attempted to remain optimistic about the future of Traveller, however, despite a virtually unanimous response from the Traveller Mailing List inquiry I did on behalf of Marc and myself, I have seen an increasing level of disagreement among various writers of the game's newest edition about the future of Stars in Traveller. I told Marc that I didn't really care too much about whether or not this added level of realism is in the game because I have gone ahead and made the appropriate fixes for my own campaign, but I thought it would be nice if Traveller were to at least fix some of the things that had been discovered in past years.

Personally, I know that some of the Astronomical "facts" in Traveller, were they to be fixed, would destroy some of the past content of the game. For example, the star Deneb is now known to be sectors away from the sector of the same name. It would be foolhardy to trash the name of that sector after so many years of players of the game being familiar with that sector, adjacent to the famous Spinward Marches. There are limits to what can be fixed in light of twenty years of experience.

GALACTIC STRUCTURE:

For many years, there has been increasing amounts of data found which support the idea that our Milky Way Galaxy may be somewhat different than originally thought. Many older Astronomy books portray our Galaxy as a regular Spiral galaxy, similar to the Pisces Spiral Galaxy (M74 seen at the left). Spirals are classed as Sa, Sb, or Sc depending upon how tight the spiral arms appear to be wrapped around the nucleus of the Galaxy. The tightly wrapped Sombrero Galaxy (M104) is an example of an Sa type while the famous Andromeda Galaxy (M31) is an example of an Sb type and the Triangulum Galaxy (M33 seen at the right) is a classic Sc type galaxy as is M74 seen face-on above.

Some galaxies show a distinct bar-like formation in their nuclei, and are thus referred to as Barred-Spiral galaxies. Their type classifications, like Spirals are SBa, SBb, or SBc.

Again, evidence has increased for the case that our Galaxy is a Barred-Spiral galaxy. Since it has always (in the past) been estimated that our Milky Way is an Sb or Sc type Spiral, I have located a picture of the Southern Pinwheel Galaxy (M83 shown at the left), courtesy of the Anglo-Australian Observatory, a galaxy that shows a slightly barred central hub region, in an effort to demonstrate that these galaxies do not differ significantly from spirals in some cases. This spiral may be an excellent twin galaxy to our own Milky Way.

A book published in 1994 entitled The Guide to the Galaxy by Nigel Henbest and Heather Couper, Cambridge University Press, has maps and diagrams that suggest that very notion: The Milky Way galaxy has a structure more intermediate to Barred Spiral Galaxies like M83 above/left. This book is the most up to date reference I have seen on the subject. It has some maps that any reality-based Traveller would drool over. It has put together the information on the galaxy, and has done so at varying degrees of detail, distance-wise outward from the Sun.

The case needs to be made for making the Universe of Traveller better resemble the known Universe of reality in light of twenty years of Astronomy experience. The Zhodani Core Expeditions were based upon a direct path to the Galactic core. Depending upon the structure of the galaxy, this may need to be adjusted somewhat.

I urge anyone reading this to use the links above to make Imperium Games and Marc Miller aware of this need. If the Universe we are playing this game in does not resemble the one the rest of us know, then is it possible for Traveller to continue to be the best SFRPG? (rhetorical)

GALACTIC DIRECTIONS:

Given the revelations about our Galaxy's structure (above), the true center of rotation is actually about 30 degrees away. This means that Traveller's use of directions like Coreward, Rimward, Spinard and Trailing need to be redone.

So much today is known about our galaxy, that Traveller can not afford to overlook or ignore these findings. True, some of the details may change in the future, but these are not likely to be as drastic as the understanding of nearby space compared to 20 years ago.

THE HELIX NEBULA:

The Helix Nebula should be (roughly) centered upon Core Sector at 1610. It should have a radius of about 1.2 parsecs around its central star. This would be be a star hex and its "zone of control." I think one of the subsectors of Core sector (B, C, F, or G) should be named Helix Nebula.

Since the majority of the Nebula falls into subsector B of Core sector, I think it is the best candidate to named thusly. The remnant central star is a White Dwarf Star (wds).

This item is especially timely since Traveller's new beginning will be starting with year 0 and the founding of the Third Imperium from the upstart Sylean Federation (Core Sector and surroundings). A few years back, I was asked about near-by Astronomical objects to which I had replied that there were none in the immediate realm of the Third Imperium. Apart from a few major bright stars, the Helix is the only prominent object from Astronomical catalogs near the Imperium. Out in the direction of Zhodani space, there are also the North American and Pelican Nebulae.

SPECTRAL TYPES FOR STARS:

The original stellar generation system for Traveller, only lightly modified for TNE, does not generate realistic companions for the primary stars. The basic problem is one of proportion. As often as not, binary stars have companions whose masses are closer to their own.

This matching occurs through all of the spectral types (colors) of the main sequence (class V stars), as well as into the Giants class (IV, III, II stars). This is not a hard and fast rule, however, the Traveller system is more likely to produce a red dwarf (M V) companion to a solar kind of star (G V), than a pair of solar stars, or a solar star and an orange dwarf (K V). These last two examples are far more likely to be found, than would a solar and a red dwarf companion.

Some excellent examples of these star combinations are Alpha Centauri, 61 Cygni, and 70 Ophiuchi.

It is nearly impossible for a pair of white main sequence stars (A V-A V) to be generated by the present system.

Note: the term dwarf is used synonymously with main sequence, both here and in Astronomical references.

GAS GIANT POSITIONING:

The Traveller placement system prefers outer zone orbits for any Gas Giant generated around the stars of the Traveller universe. This has been contradicted by recent discoveries of those searching for new worlds today, especially 70 Virginis or 51 Pegasi.

CAPTION:

The four known planetary systems around normal stars in the galaxy: our own solar system, the planet aroung 51 Pegasi, and the newly-discovered planets around 70 Virginis and 47 Ursae Majoris. One AU (astronomical unit) is the average distance between the Earth and the Sun, or 94 million miles. M Jup is the mass of Jupiter, which is 318 times the Earth's mass.

PHOTO CREDIT:

Eric Williams, Geoff Marcy & Leigh-Anne McConnaughey
UC Berkeley & SF State

BOOK 6 - SCOUTS UPDATE:

I have a draft copy of rules that are intended to update Book 6: Scouts that I think produces more realistic planetary systems. The document is now stand-alone from the rules, though there is still some more work to be done.

WHITE DWARF STARS:

A White Dwarf Star (wds) is one stellar evolutionary endpoint. The nature of the star has drastic effects on the whole system. The normal balance in a star (like the Sun) is between outward pressure generated by fusion at the core, and gravitational pressure by the star's mass. At a point in the star's life, burning goes through several steps, and the balance is thrown off--the star expands to what is called the Red Giant phase. Certain mass stars eventually burn out the fuel they shine with, and stop core fusion. At this time, with no internal pressure to balance the gravity, the Red Giant star implodes, and then explodes. The result is a shelling off of mass from the star and compression of the core into degenerate matter. This shell eventually reaches interstellar space to form a planetary (an unfortunate astronomical term that has nothing to do with planets except for the appearance through a telescope) nebula, if there is enough mass, and not too much mass.
The remnant is the wds--a hot core that no longer fuses matter and merely radiates stored heat from the days of fusion. The wds does not provide enough heat to maintain the former star's Habitable Zone and any planet there would probably be radically changed, if not vaporized from the pre-wds Red Giant stage.

SUBDWARF STARS:

Sometime before I got on-line, Subdwarfs became some kind of terrible, evil thing. I can only speculate that this came from a misunderstanding associated with their astronomical definition. The problem is, that astronomers tend to use lingo that is not very conducive to the understanding of the lay-person (like Planetary Nebula, see above). This definition is that subdwarfs are, Metal-poor stars.
Yes--there is less metal in some of these stars, but the greater extremes are found in the core regions of the galaxy. When I say core, I don't mean in Vargr space. I am talking about kiloparsecs from the Sun in the direction of the galactic core.
The Subdwarfs (like all stars, a luminosity classification) are of the broader Population II stars. These stars are generally galactic core stars. The Population I stars are characteristic of the spiral arms of the Milky Way, like our Sun. This is the classification scheme of Walter Baade of 1944, however today there are five subgroups combining the Pop I and Pop II stars in a smoother transition:
  • Halo Population II
  • Intermediate Population II
  • Disc Population
  • Older Population I
  • Extreme Population I
    • The Sun is in the fourth category (Older Pop I) and the Disc Population is a transitional category. Subdwarfs, properly, could fit in the first three categories. Those in the Universe of Traveller would be in either the Disc Pop I, or in the Intermediate Pop II.
    The attributes I have heard of subdwarfs would be that they have few planets or asteroids if any, and probably mostly gas giants. That is certainly a possible interpretation of some Halo Pop II stars, but metals are not the only factors to consider for planet-building.
    I also have to point out that all of this was understood when these stars were first described, and reasonable science-fiction authors have used the setting of metal-poor stars (hence worlds) in books. As I recall, Isaac Asimov, one of the great harder-science SF writers, did this.
    Anyway, to please any gearheads out there, the Intermediate Pop II class provides us the way out of this. One of the categories of stars (Pop II) of the class are high-velocity stars. These are moving at high orbital velocities around the galaxy, because they are in extremely elliptical orbits. Their paths bring them out to the spiral arms, where they are subsequently enriched in the metals of the spiral arm population. By the way, it does not take much to bring a metal-poor star up to normal levels, and they can form planets from such passages. It is not a requirement that a planetary system form with the associated star. In fact, it is thought that some star systems formed from the close (a few light years) passage of a star.
    The approach, in Traveller, to all of this is to generate the few subdwarfs that occur (see the draft I have written/developed) and if they only have Gas Giants for planets, then most of the GG moons will be icy balls, and this star is an older Intermediate Pop II star (assumes also high-velocity) that has yet to interact with any metal-enriched regions of the galaxy. If it does have Terrans and/or Asteroids, then it is one of the Intermediate Pop II stars, or even one in transition in the Disc Population.

    Traveller is a registered trademark of Far Future Enterprises and is used with permission.
    Portions of this material are Copyright ©1977-1998 Far Future Enterprises.
    Last Update: 12 November 2002.

    Leroy's Castle is his Home!