Poutnik wrote:

Dne 20/02/2016 v 23:07 Thomas 'PointedEars' Lahn napsal(a):
Poutnik wrote in sci.physics, sci.astro, and sci.physics.relativity:
Dne 20/02/2016 v 17:55 Thomas 'PointedEars' Lahn napsal(a):
I do not see the reason why did you hijacked my post to SPR,
as nature of topic is not SR/GR related.
Nothing was "hijacked […] to SPR", especially not "your post".

You have crossposted without Followup-To (which is unwise at best) to
sci.physics and sci.astro, and I have set Followup-To to the newsgroup
where I think that this discussion belongs. You might disagree, but
that does not give you the right to throw insults.

Follow-to is not mandatory,

That depends on the server that one uses; there are servers that would not
allow crossposting without Followup-To, or crossposting to more than three
newsgroups. There are newsreaders that would issue a warning on attempt.
At least it is the polite and recommended behavior to respect the
organization of Usenet into *topics*, and set Followup-To accordingly.
Likewise, it is the polite and recommended behavior to trim one’s quotes to
the parts that one is referring to. You did neither.

default behavior is following to crossposted groups.

Which is why it is a bad idea.

“No posting is relevant to more than a handful of newsgroups.
If World War III is announced, it will be announced in
news.announce.important.”
–Peter da Silva (translated)

See also “no spam” in http://www.eternal-september.org/index.php?language=en&showpage=terms.

Similarly ReplyTo in mails is not mandatory,
with default reply to the sender.

The important difference being that the e-mail is still directed to only a
few people or one person.

Most of stars of binary systems are not twins,
while twin stars are most probably not
a part of the same binary system.

It is the modern definition of a binary star (system) that it is actually
two stars revolving around a common center of mass. You are confusing
*double* stars with *binary* stars and *twin* stars.

A “twin star”, by contrast, would be *one* star that has approximately
the same characteristics as another star (cf. “twin planet”) where
nothing would be implied about their orbits. But your definition above
proves that you were not referring to that.

No, you have misinterpreted my words.
You can see there is no redundancy.
2 stars being twins and being bonded in binary system
are 2 indenpendent pieces of information.

I have not misinterpreted your words. You have claimed that “twin stars are
most probably not a part of the same binary system.” Lack of evidence
notwithstanding, as “twin star” usually means something else than you think
it does, your statement is nonsense. You can invent your own terminology,
but you should not be surprised if that leads to misunderstandings and
others frown when you insist on that only your private terminology is the
correct one.

Therefore, as Isaac Newton (1687) showed already, Kepler’s laws are
only an approximation of the observed planetary motion.
^^^^^^^^^^^^^^^^
But it is not fully the case of the 3rd law with sum of masses.
^^^^^^^^^^^^^^^^^^
I beg your pardon?

..obsessive nitpicking arrogance...

/Ad hominem/ again because you cannot face the fact that your statement
is wrong. In fact, both you and the resource that you cite claim that
the approximation of Kepler’s laws *holds* in the case of binary stars.

It is applicable as well for planet-moon systems

No doubt about that, although there appears to be no official (IAU)
definition what distinguishes a planet–moon system from a double planet
system.

It does not really matter, it can be generalized to all 2 body systems,

Then there was no reason to mention this as a special case, was there?

where GR effects can be still beglegted.

YSCIB.

GR effects for stars of Sun mass at distance 2 AU are very minor,

There are stars in binary star systems that have masses greater than the
Sun and a minimum distance from each other less than 2 AU. For example,
Eta
Carinae A has ≈120 to {170 to 200} M☉, and Eta Carinae B has 30 to 80 M☉
[1], while the minimum distance between the stars is estimated to be 1.6
[AU 2] (the orbits are highly eccentric, which is why it took so long to
recognize that Eta Carinae is actually a binary star system).

https://en.wikipedia.org/wiki/Eta_Carinae

I am aware about Eta Carinae.

So you were deliberately misrepresenting the facts, i.e. lying? Because Eta
Carinae, for example, shows that you are proceeding from a false assumption,
namely that GR would never be needed to describe binary star systems
*properly*.

and negligible wrt to accuracy of data.
Either do the math or cite evidence in which the math is done.

If you think about it more, you will agree,
considering accuracy of the periods and distances.

IOW, you are not able or willing to substantiate your claims. Figures.

Score adjusted.

F'up2 sci.physics.relativity

PointedEars
--
Q: What did the female magnet say to the male magnet?
A: From the back, I found you repulsive, but from the front
I find myself very attracted to you.
(from: WolframAlpha)