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Can amateurs detect binary orbits?

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#1 jerwin

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Posted 16 February 2013 - 11:25 AM

Question for you binary star enthusiasts. Can amateurs/amateur telescopes detect the orbits of binary starts around each other? If the answer is yes, is it typically over the course of several years or is it faster than that? I’m sure the speed would vary depending on the binary system but in general, can we detect it.
Would it be that February 16th, 1983 the companion star was on the left and 30 years later it's on the right, or is it much more subtle, where it's just slightly closer after 30 years?
I've read of variable binaries and seen animations but I feel like that orbit can't be as fast as a normal variable star changes it brightness.
Appreciate your input.
Jim

#2 Astrojensen

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Posted 16 February 2013 - 12:29 PM

Oh yes! And in quite a few pairs, even. Castor comes to mind, as does Gamma Virginis and Gamma Andromedae BC. Castor has clearly widened a lot in my time as an amateur astronomer (twenty years). Gamma Virginis changed position angle through almost 90° in less than a year, when it was closest a few years ago. Zeta Bootis has closed markedly during the past decade. I used to use it as an elongation test in my 80mm, but now it's impossible. Sirius is another favorite, with an orbital period of 50 years, so it's possible to follow a complete orbit in one human lifetime. There are many more.


Clear skies!
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#3 jerwin

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Posted 16 February 2013 - 12:38 PM

Thank you Thomas. I was hoping the answer was yes but size, time and distance are a lot different in space than I can even pretend to understand.

I wasn't sure if things took a year, a 10 years, 10 thousand years or 10 million years.

Truly appreciate your knowledge on the subject.

Jim

#4 gregj888

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Posted 16 February 2013 - 11:45 PM

Jim,

Depending on how deep you want to get, you can split some very close doubles ( < 0.7 arcsec). Check out "lucky imaging" and "Speckle interferometry" (Reduc).

http://www.clearskyo...ble-star-plates

http://www.ast.cam.a...jects/lucky....

http://www.altazinit...blStar-Home.htm

Sorry to just post links, but there's a lot of information that's presented better than I can.

Debending on the size of the scope and location oc course. Several at the conference presented results < 0.6 arcsec with 20" scopes.

Greg

#5 azure1961p

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Posted 17 February 2013 - 09:36 AM

They move relatively slow to centuries long but the *faster* ones can be had over a few years time in terms of seeing widening or closing distances. I'm currently waiting for Andromedae Bs component to become visible if even partially again through my 8". Glen Chapil of Astronomy mag had a decent article on such *fast movers* some issues back. Then there are doubles like Albireo that would seem to take thousands of years leading even some to believe maybe they aren't really orbiting but merely a chance alignment of relatively close distance.

For this kind of pursuit the greater your aperture the longer the list of available doubles that make apparent motion detectable. Medium aperture and larger would be the way to go.

Pete

#6 Ed Wiley

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Posted 17 February 2013 - 12:42 PM

As Greg said, it all depends on how deep you want to get into this field. Another way of "seeing" the movement is to obtain all the historical measures and plot them. Then do you own measures and see how you stack up with the previous results. To do so you need to know how to work the Washington Double Star Catalog, how to request the data and a bit of data processing (all covered in various JDSO articles). Some of the Herschel and Struve (STF) doubles have histories that date back to the later 18th century and many of the pairs with known orbits have hundreds of observations. An example is attached, its STF73AB and the red dot is my measure.

There is all sort of observational and "armchair" fun you can have with doubles.

Ed

Attached Files



#7 FlorinAndrei

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Posted 17 February 2013 - 05:35 PM

I wasn't sure if things took a year, a 10 years, 10 thousand years or 10 million years.


All of the above. Well, maybe not the millions. It depends on the distance between components, and on their masses. Components closer to each other, and/or more massive, orbit each other more quickly. Larger distances and/or less massive stars - slower orbits.

#8 PJ Anway

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Posted 18 February 2013 - 09:52 PM

One of my favorites is 70 Ophiuchi, with an 88-year orbit.

#9 Astrodj

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Posted 19 February 2013 - 01:22 AM

Below is a link to part 5 of a five part write-up about stars with orbital periods amateurs can follow visually.

Be sure to check out parts 1-4 also.

http://admin.prairie...rg/dblstar5.htm

#10 WRAK

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Posted 19 February 2013 - 04:01 AM

DJ, great link, thanks.
Wilfried

#11 PJ Anway

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Posted 19 February 2013 - 02:29 PM

Below is a link to part 5 of a five part write-up about stars with orbital periods amateurs can follow visually.

Be sure to check out parts 1-4 also.

http://admin.prairie...rg/dblstar5.htm


Here is their "new" site:

Prairie Astronomy Club

#12 Astrodj

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Posted 19 February 2013 - 05:12 PM

Thanks PJ! :thanx:






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