T5 Web Apps

[whulorigan]

Yerkes type VI are, as far as i can tell, low metalicity low initial helium main sequence stars.
On the HR diagram, they're a parallel line, and only exist in the G5-M5 spectra.

CORRECT. That is an accurate description of what a Subdwarf is. The low metallicity and low initial Helium are believed to be due to the fact that (often) they are older stars. The low metallicity results in a physically smaller (less luminous) star. Most are found in eccentric orbits at all angles in the galactic halo, but some are found in the Galactic Plane as they intersect it on their orbits.

Type VII are "white dwarves" in the O7 (or so) to K5 range. The remnants of dead main sequence stars below the black hole threshhold.

"Type VII" is the older (discontinued) classification for White Dwarf. The "D(Letter)(Decimal)" classification is the current scheme. *

* - The Letter and Decimal do not correspond to the Yerkes scheme for Main Sequence Stars, however. There are in fact no White Dwarfs whose tempertaure would correspond to normal star values below "K4-5" on the Yerkes scale.
​

 

[inexorabletash]

Hey Admins - is it possible to split this thread off?

 

[aramis]

Traveller pretty much has always used the Yerkes system. Only T5 uses the revised Yerkes.

Also, the older versions of the spectral class system included a longer sequence...
OBAFGKMNS.

N and S were dropped when the definitional aspect of stars was discovered to be that they fuse... and so the N and S were expected never to be found (thought to not exist at all), and got dropped. In the meantime, they got reused for other (high metalicity) stars...

And then they found them. So the relabeled the old N and S ranges with L, T, and Y. Low end main sequence V & VI sizes can be burning into the L range, and non-burning but newly collapsed substellar objects can be as warm as mid M, while smaller ones may start in the L or Y ranges.

The whole thing gives me headaches. Every time I start to get a handle, some new change to the nomenclature is passed by the IAU. Or introduced in new academic papers, and adopted.

Some of the new classification affixes also leave me in head scratcher mode.

 

[DonM]

And it probably doesn't help that T5SS is only partially complete in the stellar data cleanup. I'd focused more on other elements than the stellar data recently. We did do quite a bit of stellar cleanup, but we also recognized there was more work to do in that area.

For example, the next release of T5SS data will have a four-character polity code rather than two-character (Im will probably become 3Imp, although that's not fully worked out yet.

Definitely an "after Winter War" project...

 

[thalassogen]

All this talk of T5SS and my google foo failing - where do I get this data/spreadsheets/etc.? (Besides downloading each sector via the TravellerMap API.)

 

[inexorabletash]

All this talk of T5SS and my google foo failing - where do I get this data/spreadsheets/etc.? (Besides downloading each sector via the TravellerMap API.)

The closest to the raw data to the raw SS data is the various .tab files in the TM source - these are generated by opening up the spreadsheet and saving out a worksheet - automated by a script.

https://github.com/inexorabletash/travellermap/tree/master/res/Sectors

The data available through the API comes from loading these .tab files, parsing them, doing some cleanup (e.g. de-capitalizing HiPop world names, etc), and re-serializing. So it's possible something is lost in that process.

 

[whulorigan]

And it probably doesn't help that T5SS is only partially complete in the stellar data cleanup. I'd focused more on other elements than the stellar data recently. We did do quite a bit of stellar cleanup, but we also recognized there was more work to do in that area.

For example, the next release of T5SS data will have a four-character polity code rather than two-character (Im will probably become 3Imp, although that's not fully worked out yet.

Definitely an "after Winter War" project...

In that case, I will wait patiently since it is a work in progress.
(Or at least semi-patiently).

 

[thalassogen]

https://github.com/inexorabletash/travellermap/tree/master/res/Sectors

Ah, thank you!

 

[DonM]

In that case, I will wait patiently since it is a work in progress.
(Or at least semi-patiently).

I'll confess that we had a plan, but then Marc needed all the Imperial UWPs for some T5 nobility grant project... so we sort of focused completely on that, and then started back at the plan, and then...

I really, really need to get all my stuff reorganized. After Winter War.

 

[inexorabletash]

After more reading of both real-world stellar classification and older Traveller editions, it's clearer to me that yes, D in Traveller is intended to be for white dwarf stars. Mea culpa. The T5SS data had biased me into thinking "all white dwarfs are the same and are all WD" but that doesn't match Traveller precedent, T5SS data, or the real world. I've updated http://travellermap.com/doc/secondsurvey.html#stellar with what I hope captures the state of the data better.

So far as I can tell, you could refer to the same stellar remnant in Traveller as: M0D (blindly following the generation rules), MD (omitting the decimal), DM (older editions, e.g. Bk6, MT) or WD (per T5SS data). And that still doesn't match the real world where different spectral letters are used (A B C O Z Q X) following the D prefix.

 

[aramis]

And that still doesn't match the real world where different spectral letters are used (A B C O Z Q X) following the D prefix.

Which simply tell you what the atmosphere of that core is.

 

[whulorigan]

After more reading of both real-world stellar classification and older Traveller editions, it's clearer to me that yes, D in Traveller is intended to be for white dwarf stars. Mea culpa. The T5SS data had biased me into thinking "all white dwarfs are the same and are all WD" but that doesn't match Traveller precedent, T5SS data, or the real world. I've updated http://travellermap.com/doc/secondsurvey.html#stellar with what I hope captures the state of the data better.

Your new table is much clearer. Thanks.

So far as I can tell, you could refer to the same stellar remnant in Traveller as: M0D (blindly following the generation rules), MD (omitting the decimal), DM (older editions, e.g. Bk6, MT) or WD (per T5SS data).

Personally I like the simple "D" or "WD" for White/Degenerate Dwarfs, but none of the rulesets generate that particular code, as far as I can see. It is curious that the T5SS includes it.

And that still doesn't match the real world where different spectral letters are used (A B C O Z Q X) following the D prefix.

In the real world, the spectral classification of all stars has to do with the actual thermal emission spectrum as well as absorption lines due to the presence of particular elements in the star's spectrum.

In regular stars, this generally correlates with the star's surface temperature (and hence color). In White/Degenerate Dwarfs, the Spectral Classificaton has far more to do with the absorption lines, and does not neatly correspond to surface tempertaure (and hence the spectral classification codes are quite different due to the presence of different substances). When temperature is included in a White Dwarf Spectral Classification, it is a decimal number ("N") at the end of the code (and represents the temperature of the WD as: Temp (^oK) = 50400 ^oK / N. So a DZ3 White Dwarf would have a surface temperature of 50400/3 = 16800 ^oK.

Traveller (when it assigns spectral classifications to White Dwarfs) uses the Spectral Classes of regular stars for simplicity sake (since most Traveller campaigns are concerened with stellar temperature, and are not overly worried about what elements are present in stellar atmospheres). Using the above formula to calculate the tempertaures and convert to "normal" stellar codes for Traveller purposes generates a range from "Late" OD ("D_1") thru early KD ("D_9"). No MD dwarfs have ever been observed, which matches with current theory, as the Universe is not actually old enough yet for WD's to have cooled down that far.

 

[inexorabletash]

Personally I like the simple "D" or "WD" for White/Degenerate Dwarfs, but none of the rulesets generate that particular code, as far as I can see. It is curious that the T5SS includes it.

I'm of two minds; on the one hand, the spectra of a white dwarf really shouldn't matter to a game of Traveller; unlike the system's primary, the precise details of the bright but point-like companion isn't going to really change the visual appearance of the system or affect navigation. On the other hand, using WD everywhere detracts from the "real world flavor" of the stellar data. If real white dwarf classification isn't going to be used, though, I'd prefer just WD everywhere.

The stats show that the T5SS stellar data can and should (for consistency) be tweaked, and will have minimal consequence on the bulk of the dataset regardless of what approach is taken.

And since we've totally derailed this thread....

T5 introduces the non-standard BD for brown dwarfs (real is a subset of L stars, plus T and Y). Is there any need for a classification of other types? The two that come to mind are the other degenerate star types: neutron stars (and pulsars), and stellar-mass black holes. Or is a catch all of Un plus documentation sufficient? (Looking at statistics, there should be a few neutron stars in charted space, unlikely to be any black holes.)

 

[aramis]

I'm of two minds; on the one hand, the spectra of a white dwarf really shouldn't matter to a game of Traveller; unlike the system's primary, the precise details of the bright but point-like companion isn't going to really change the visual appearance of the system or affect navigation. On the other hand, using WD everywhere detracts from the "real world flavor" of the stellar data. If real white dwarf classification isn't going to be used, though, I'd prefer just WD everywhere.

Actually, as one "descends" the chromatic sequence, the brightness should tend to decline as it cools, and the color will shift as well due to blackbody radiation color changes.

On that score, it's actually MORE useful to retain the no longer used OBAFGK (with O3 being about +11 magnitude, and K5 or so being about +14.5 Magnitude, from looking at the HR diagram), than to use the now current WD_ (which doesn't specify temp, color, nor magnitude, but does tell what is in the atmosphere.)

 

[inexorabletash]

T5 introduces the non-standard BD for brown dwarfs (real is a subset of L stars, plus T and Y). Is there any need for a classification of other types? The two that come to mind are the other degenerate star types: neutron stars (and pulsars), and stellar-mass black holes. Or is a catch all of Un plus documentation sufficient? (Looking at statistics, there should be a few neutron stars in charted space, unlikely to be any black holes.)

Apparently, MgT's Aslan places a black hole in the 627-301 system in Trojan Reach. It's not noted in the T5SS stellar data.

http://travellermap.com/world?sector=Trojan Reach&hex=3003

 

[DonM]

Yes. That's a known item. There's several questions I ask whenever it comes up, and I'm sure that others could come up with even more.

And you guys have already summarized a year's worth of stellar classification arguments in this thread. Thank you for that, and I see you haven't come to a consensus either

 

[stevenspizick]

would love to see character generator in future???

 

[thalassogen]

A character generator is intended. I am just waiting for a new errata document to continue my work. It may even be possible that I will release it not only as part of the web apps, but also as an offline app like http://jochenlinnemann.de/?page_id=82

 

[thalassogen]

I am currently focusing on other projects and still awaiting errata, but as we are working on an LBB-like PDF output for your sectors which should eventually be read like Library Data entries, I thought I could as well share the current state with you.

Just upload a sector or create a random one and then click the button "Create LBB-inspired PDF file".

Have fun!

 

[Magnus von Thornwood]

Black holes, big deal.

Seriously while I agree having neutron stars, pulsars, and other neato stars, black hole (excepting galactic scale ones) aren't that impressive gravitionally. Sure once roll up on it sure, but it runs out the event horizon is fairly small as in 10s to 100s of kilometers. Unless you run over it in jump space somehow, it should never bother anyone. And since this is marked, everyone should be safe.

It's thEm uncharted ones that keep me on watch.