[Space] the problem with Sol

[Agemegos]

G'day

Sol's mass is by definition 1.0, and it's age is currently believed to be 4.8 billion years. It is categorised as G2 V, and its radius is 696 000 km. Let's work through its stellar characteristics using Step 18 of the Star System Generation sequence on pp. 102–105.

Mass = 1.0 implies M-span = 10. Age < M-span so the star is main-sequence.

From the table on p 103, MIN = 0.68, MAX = 1.60, S = 10, M = 5,800

L = MIN + [(A/S) * (MAX - MIN)]

= 0.68 + [(4.8/10) * (1.6 - 0.68)]

= 0.68 + 0.48*0.92

= 1.1216

R = (155,000 * sqrt(L))/T^2, where T = M for a main-sequence star

= 0.00488 AU

= 730 006 km

Close enough, do you think?

Regards,


Brett

[Anders]

Certainly. I believe it says that it's reasonable to modify all stats by 10% either way.

Edit: And I thought it was 4.6 billion years - but that may be old figures. And there are some people who say 6 000 years... :)

[Hex]

Originally Posted by Asta Kask

Edit: And I thought it was 4.6 billion years - but that may be old figures. And there are some people who say 6 000 years... :)

I thought it was 10,000 years...but I guess it can be modified by 10% either way.

Hex≈

[Anders]

According to most medieval authorities, the earth was created somewhere around 4 000 BC. That would place it at about 6 000 years.

[Kaldrin]

At first there was nothing... then God said, "Let there be light." And there was still nothing, but at least you could see it wasn't there.


I love how people ignore the basic interpretation in the bible. The actual translation of the term most think is 'day' is actually 'period of time'. It's in indefinite amount of time as it's written. The original language doesn't even give any indication that those periods were actually the same length...

As for Space being accurrate regarding our own main sequence star, well, I think that's just snazzy. :)

[jacobmuller]

Originally Posted by Kaldrin

At first there was nothing... then God said, "Let there be light." And there was still nothing, but at least you could see it wasn't there.
I love how people ignore the basic interpretation in the bible. The actual translation of the term most think is 'day' is actually 'period of time'. It's in indefinite amount of time as it's written. The original language doesn't even give any indication that those periods were actually the same length...
:)

yes, the folk who believe absolutely that TOTG created all in 6x24hrs and can give you a comparative date and time for it (October 15th, 6.35am, 4378 BC or somesuch {preceding data is gibberish}).
TOTG is infinite and eternal; time is relative; if you exist without beginning or end then the time since the universe began means nothing and trying to explain infinity to a mere human who hasn't even heard of the concept of nothing... (nothing, i.e. 0, was invented by medieval Arabs? Or at least 1-9 were. Hard to believe no-one could count properly before it... and they still built a clockwork solar system, etc)

Oh, and that is way cool that the numbers do work for the baseline star. I hate it when things don't match up...

[Phantasm]

Originally Posted by Asta Kask

According to most medieval authorities, the earth was created somewhere around 4 000 BC. That would place it at about 6 000 years.

While this is backed up with the first acknowledged civilization, ancient Sumeria, being that old, there is archeological evidence of what the experts call "proto-civilizations" that go back even father: there are ruins of the city of Jericho that go back to 7000 BC, Catal Hüyük in central Turkey dates back to around 6000 BC, and let's not forget the Ice Age hunters who were around ca 10 000 BC or thereabouts.

Dipping into "fringe archeology", there are some theories that a civilization, now lost, existed in the Nile Valley and elsewhere around 10 500 BC or so and was wiped out by the flooding that accompanied the glaciers melting at the end of the Ice Age. Two pieces of evidence support this, but are disputed by "conventional" archeologists: the erosion on the lower half of the Sphinx has been shown to be water damage, and precession - around that time frame, the constellation Orion, which the Egyptians identified with their god Osiris, would have been seen "standing" on the horizon in the spring.

I happen to know from experience that mentioning any of this to those who believe the first chapters of Genesis to be "100% literal" brings forth all sorts of arguements like "carbon-dating is a crock", "precession doesn't happen", and whatnot (never mind that, to my knowledge, it is impossible to carbon-date non-organic rocks).

[Woodman]

For poeple with a relaxed viewpoint on the matter of creation i would recommend "Strata" by Terry Pratchett, its a non discworld novel and explains how things are created and why one finds nice bones in the soil of a planet wich isnt even 20 years old.

[David Johnston]

It's a little surprising that the standard formula won't yield the Sun without fudging but not a big deal. What I'm worried about is this:

I have a planet orbiting the brown dwarf Epsilon Indii B.
It's orbiting at .05 AUs, just outside the inner limit of .04 AUs for
a mass .4 Brown dwarf. It's only 1.3 billion years old. Lumininosity
.0097. Does my planet really have a Black Body temperature of 390
degrees? What am I doing wrong?

[Agemegos]

Originally Posted by David Johnston

I have a planet orbiting the brown dwarf Epsilon Indii B.
It's orbiting at .05 AUs, just outside the inner limit of .04 AUs for
a mass .4 Brown dwarf. It's only 1.3 billion years old. Lumininosity
.0097. Does my planet really have a Black Body temperature of 390
degrees? What am I doing wrong?

Looks right to me. 390 kelvin. 117 C. 243°F

It's a dim star, but your planet is damned close. R^2 is less than L, so insolation is greater than that on Earth. So the blackbody temperature is higher.