Pedantic..?
- Thread starter Sugarat
- Start date
There are a number of inconsistencies between the star descriptions in the system map and the actual underlying values used by the Forge, with respect to both mass and temperature ranges.
Additionally, there are stars whose description from the cockpit info panel and system map does not match their spectral class given on the galaxy map - for example I recently visited LEAMI JG-Y E434, a G supergiant with a galaxy map spectral class G7 IAB shows as an "F Supergiant" in the system map and info panel.
The actual temperature ranges so far as I know are;
0 <Y< 700 < T< 1300 < L < 2000 < M, MS, S, CN < 3700 < K < 5200 < G < 6000 < F < 7500 < A < 10000 < B < 33000 (?) < O < 70000 (?)
In game these are divided into ten equal subdivisions each, from 9 (coolest) to 0 (hottest).
In reality things are not as simple and stars can't be neatly parceled up into discrete batches. The divisions between spectral types broadly correspond to differences in the way the stars are burning fuel, which is affected by their mass but also by their composition and many other features, so while approximate values can be given for the boundaries between spectra you'll find they're not necessarily consistent.
If needed I can provide some broad values for the mass ranges (one of note: the line between TTS and He Ae/Be seems drawn at 3 solar masses), it'll take a little time to draw them out of the data. This chart may be of interest.
Additionally, there are stars whose description from the cockpit info panel and system map does not match their spectral class given on the galaxy map - for example I recently visited LEAMI JG-Y E434, a G supergiant with a galaxy map spectral class G7 IAB shows as an "F Supergiant" in the system map and info panel.
The actual temperature ranges so far as I know are;
0 <Y< 700 < T< 1300 < L < 2000 < M, MS, S, CN < 3700 < K < 5200 < G < 6000 < F < 7500 < A < 10000 < B < 33000 (?) < O < 70000 (?)
In game these are divided into ten equal subdivisions each, from 9 (coolest) to 0 (hottest).
In reality things are not as simple and stars can't be neatly parceled up into discrete batches. The divisions between spectral types broadly correspond to differences in the way the stars are burning fuel, which is affected by their mass but also by their composition and many other features, so while approximate values can be given for the boundaries between spectra you'll find they're not necessarily consistent.
If needed I can provide some broad values for the mass ranges (one of note: the line between TTS and He Ae/Be seems drawn at 3 solar masses), it'll take a little time to draw them out of the data. This chart may be of interest.
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Rather not, or else my head won't fit in the pilot's helmet anymore.
They make bigger helmets
. Haha, well as knowledgeable as some people are now after playing ED, apparently standard forum rules still apply. And if a couple hours go by, some people don't read whole thread before replying, even when I post a colorful friendly eye catching graphic to entice people to people to read. Here's a secret: This is the 2nd time I've posted this exact response to a similar question. But the forum amnesia doesn't always win. Usually by the 3rd or 4th similar posting, I'll see someone else beat me to the punch with an accurate response (ie one that required them to verify the info with other sources in depth and really learn it!). Then I feel like it's all worth worthwhile
First off, kudos on finding proof that the game takes main sequence evolution into account.
Let me explain,
The F class can be almost any mass, however what defines it is the temperature. And F class temp ranges between 6000 - 7500 K. The surface temperature is what determines the spectra of emission as well as the peak frequency of light emitted. The peak frequency determines the color. Which is why hot low mass white dwarves are white, and cool high mass giants are red. Temp and spectra are the things we can measure directly from earth. Mass is only measured indirectly, and after the spectra is determined.
Also, and this is important: The notes describe a common main sequence mass at birth.
Now here's where it gets a little complex. For stars under 1.5 solar masses are powered more by the P-P chain, the temperature increases as it gets older, however, for stars that are over 1.5 masses powered by the CNO cycle, the temperature decreases after birth onto the main sequence. So here we have a 0.5 billion year old star, that started life at the very low end of the A class and then steadily cooled down to just under 7500 K thus transitioning to an F class spectrum. From white to bright yellow, thus F.
View attachment 101722
Tldr:
Larger stars cool down slightly as they age on the main sequence, and can drop a letter class on the OBAFGKM "scale" if they're on the borderline while keeping (pretty much) the same mass.
One thing I'd love (with a capital "L") would be if the stellar data pane included metallicity. High metallicity stars are redder, which can also account for a high mass star showing up as a lower stellar classification.
I totally agree with you, though. I love that this game at least attempts to model stellar evolution! <3
Which means that you my dear CDMRs are several steps ahead of most people who have taken undergrad university astronomy courses. Let that sink in.
I bet many of those play ED too
.Yes, excellent catch! It certainly could be high metallicity reddening the star as well, but we don't yet know if metallicity is an actual factor in stars physical characteristics in the stellar forge. It is certainly a variable for systems. But we can only look at the planets which are a potential byproduct of star's metallicity and at their metal vs rock percentage to guess at a system wide Fe/H ratio. The stars themselves however are complete unknowns, and the only evidence we have that stellar metallicity comes into play are the extraordinary long lifespans of high mass B stars.
In either case, 578 milion years is sufficient time for this particular star to cool down ~40K which is enough to carry it over the soft boundary into the F category. It could definitely be both facets at play here though
I bet many of those play ED too
I certainly hope so!!! Assuming they play PC games and have heard of it. I didn't hear about until April 2015, and I am something of an avid PC gamer.
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Speaking of "soft boundaries" I just realized that ED uses 1.4 masses and 7600 K for the upper A-F boundary, rather than 1.5 and 7500 K. In astronomy, you get used to huge error bars on some figures and also the inconsistencies of and overlapping boundaries of classifications. Somethings we can know with astounding precision, and others are only "order of magnitude" correct. Including temperature. Even so, I am going to say that the aging alone probably wouldn't account for the temperature difference of 127 K and the extra .14 solar masses. So maybe metallicity is a factor after all? Or maybe the game has stars that are "variable" and were caught on one side of the cycle of expansion/contraction. The A-F boundary is within the "instability strip" on the H-R diagram so it's feasible and even likely to be the case, or at least a contributing factor. OK well now I am REALLY wondering how complex the sim is?
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Rule 2: If there is an exception to a rule it is not a rule.
A sufficiently complex system will seem to break its own rules. But really, it just means that we don't fully understand the rules.
If there's anything in this thread that is ripe for pedantic replies, it's this.
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Jon474
Banned
I, too, am loving this thread.
In fact, I think there are some seriously clever people contributing to the Exploration threads at the minute...ooh, "Threads". Wasn't that a TV program from a few years back? Contributions are impressive and I am learning so much.
Kind regards
Jon
T-6E pilot
PS: @OP I hope you did not take offence at my own pedantry earlier today. It was genuinely an attempt at humour! Really, though, I have never been very good at that.
In fact, I think there are some seriously clever people contributing to the Exploration threads at the minute...ooh, "Threads". Wasn't that a TV program from a few years back? Contributions are impressive and I am learning so much.
Kind regards
Jon
T-6E pilot
PS: @OP I hope you did not take offence at my own pedantry earlier today. It was genuinely an attempt at humour! Really, though, I have never been very good at that.
First off, kudos on finding proof that the game takes main sequence evolution into account.
Let me explain,
The F class can be almost any mass, however what defines it is the temperature. And F class temp ranges between 6000 - 7500 K. The surface temperature is what determines the spectra of emission as well as the peak frequency of light emitted. The peak frequency determines the color. Which is why hot low mass white dwarves are white, and cool high mass giants are red. Temp and spectra are the things we can measure directly from earth. Mass is only measured indirectly, and after the spectra is determined.
Also, and this is important: The notes describe a common main sequence mass at birth.
Now here's where it gets a little complex. For stars under 1.5 solar masses are powered more by the P-P chain, the temperature increases as it gets older, however, for stars that are over 1.5 masses powered by the CNO cycle, the temperature decreases after birth onto the main sequence. So here we have a 0.5 billion year old star, that started life at the very low end of the A class and then steadily cooled down to just under 7500 K thus transitioning to an F class spectrum. From white to bright yellow, thus F.
View attachment 101722
Tldr:
Larger stars cool down slightly as they age on the main sequence, and can drop a letter class on the OBAFGKM "scale" if they're on the borderline while keeping (pretty much) the same mass.
Rep for you sir.