Binary system

Phy_enthusiast · Sep 22, 2013

which is the first binary star system discovered ever?

Drakkith · Sep 22, 2013

According to wiki it's Xi Ursae Majoris.

http://en.wikipedia.org/wiki/Xi_Ursae_Majoris

Phy_enthusiast · Sep 23, 2013

ok.but is it the first ever known to man???

Drakkith · Sep 23, 2013

Per wiki:

Xi Ursae Majoris (Xi UMa, ξ Ursae Majoris, ξ UMa) is a star system in the constellation Ursa Major. On May 2, 1780, Sir William Herschel discovered that this was a binary star system, making it the first such system ever discovered.

I'd say that's a yes.

Phy_enthusiast · Sep 23, 2013

but there are ancient records that people identified some stars to be binary....even before gravity was discovered.

Drakkith · Sep 23, 2013

Phy_enthusiast said: ↑

but there are ancient records that people identified some stars to be binary....even before gravity was discovered.

Those are visual binaries. Some of them have turned out to be real binary stars, but no one actually knew about gravitationally bound binary stars until 1780.

Vanadium 50 · Sep 23, 2013

Phy_enthusiast said: ↑

but there are ancient records that people identified some stars to be binary....even before gravity was discovered.

Please provide references for this. Especially if you are going to claim the answer you got was wrong.

snorkack · Sep 23, 2013

Consider the other easy binaries...
from
http://www.ianridpath.com/binaries.htm
Xi UMa/Alula Australis - semimajor separation 2,5´´, period 60 years, magnitudes 4,3/4,8
for comparison:
Eta Cas - 12´´, 480y, 3,5/7,4
Alpha For - 4,0´´, 269y, 4,0/7,2
Castor - 6,8´´, 467y, 1,9/3,0
Gamma Leo - 4,2´´, 510y, 2,4/3,6
Gamma Vir - 3,6´´, 169y, 3,5/3,5
Toliman - 7,6´´, 80y, 0,0/1,3
Xi Boo - 4,9´´, 152y, 4,8/7,0
44 Boo - 3,7´´, 210y, 4,8/6
70 Oph - 4,5´´, 88y, 4,2/6,2
61 Cygni - 24,3´´, 678y, 5,4/6,1
Zeta Aquarii - 3,4´´, 487y, 4,3/4,5

It is odd that Alula Australis should have been the first... compared to say 70 Ophiuchi and especially Toliman.

Phy_enthusiast · Sep 23, 2013

from ancient times it is known in indian astronomy that two stars mizar and alcor is a binary system in big dipper asterism.

Phy_enthusiast · Sep 23, 2013

it is probably the most ancient and first of its kind discovered in sky by early astronomers

Drakkith · Sep 23, 2013

Phy_enthusiast said: ↑

from ancient times it is known in indian astronomy that two stars mizar and alcor is a binary system in big dipper asterism.

Phy_enthusiast said: ↑

it is probably the most ancient and first of its kind discovered in sky by early astronomers

Yes, but they didn't know it was an actual binary star at the time. And by "actual" I mean two stars gravitationally bound to each other.

Phy_enthusiast · Sep 23, 2013

It is mentioned in indian texts that one of the star moves ahead of other over certain period of time and then the first one moves ahead of second one.this obserbvation of movement clearly indicates first sign of astronomical phenomenon of binary star.

Phy_enthusiast · Sep 23, 2013

This observation was made over a course of many centuries in indian astronomy.

Drakkith · Sep 23, 2013

Mind giving a reference?

Phy_enthusiast · Sep 23, 2013

You can search for Vashistha and arundhati on internet.These are the ancient indian name for Mizar and alcor.

Drakkith · Sep 23, 2013

Throwing them into an orbital period calculator gives me an orbital period of approximately 10 million years. Assuming I'm within even an order of magnitude, it seems unlikely that ancient indians could know they moved with each other. The time scale is simply too long. Even over 5,000 years their orbital motion would not be able to be seen.

jim mcnamara · Sep 23, 2013

A reference is not a "google search" for two star names. Please. We want real references here. Do you know what that means? An article written by an expert astronomer, could be a hundred years old. Observations you mention were made visually a long time ago and cannot be verified as an observation of a real gravity-bound system.

This seems like a rhetorical post to me. You assume you already know the answer, and it appears that you do not.

Thanks.

Phy_enthusiast · Sep 25, 2013

I dont know the answer, i suggested alcor and mizar because it was observed before william herschel discovered other binaries.I think they were first visual binaries ever discovered.But there proper motion was also studied by ancient indians.

Drakkith · Sep 25, 2013

Phy_enthusiast said: ↑

I dont know the answer, i suggested alcor and mizar because it was observed before william herschel discovered other binaries.I think they were first visual binaries ever discovered.

Alcor and Mizar have been known as a visual double since before antiquity.

But there proper motion was also studied by ancient indians.

I don't see how. They are WAAAY too far apart for their orbital motion around each other to be noticeable over a few thousand years. Especially before the invention of the telescope in the 1600's. It's likely that any reference to them moving around each other is based on something other than visual observation.

phinds · Sep 25, 2013

Drakkith said: ↑

It's likely that any reference to them moving around each other is based on something other than visual observation.

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Binary system

Phy_enthusiast

Drakkith

Staff: Mentor

Phy_enthusiast

Drakkith

Staff: Mentor

Phy_enthusiast

Drakkith

Staff: Mentor

Vanadium 50

snorkack

Phy_enthusiast

Phy_enthusiast

Drakkith

Staff: Mentor

Phy_enthusiast

Phy_enthusiast

Drakkith

Staff: Mentor

Phy_enthusiast

Drakkith

Staff: Mentor

jim mcnamara

Phy_enthusiast

Drakkith

Staff: Mentor

phinds

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