Binary Stars Observable with Binoculars: Periodicity

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SUMMARY

This discussion centers on the visibility of binary stars with binoculars, specifically focusing on Alpha Centauri and Algol. Alpha Centauri, the nearest binary star system, can be resolved with a 6" reflector or a reasonable refractor, but not typically with binoculars due to its close separation. Algol, with an orbital period of just under 3 days, exhibits observable brightness changes to the naked eye during eclipses, but does not allow for resolution of individual stars. The discussion highlights the challenges of observing binary stars with short orbital periods and the limitations of current observational tools.

PREREQUISITES
  • Understanding of binary star systems
  • Familiarity with telescope types, specifically reflectors and refractors
  • Knowledge of stellar brightness and magnitude scales
  • Basic concepts of orbital mechanics and separation distances
NEXT STEPS
  • Research the observational capabilities of different telescope types for binary star resolution
  • Learn about the light curves of eclipsing binary stars, focusing on Algol
  • Investigate the orbital dynamics of Alpha Centauri and its historical separation
  • Explore advanced binocular options for astronomical observation
USEFUL FOR

Astronomy enthusiasts, amateur astronomers, and educators interested in binary star observation and the limitations of binoculars versus telescopes.

thetexan
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Are there any binary stars that can be seen with binoculars which have orbital periods you can observe from week to week or month to month?
tex
 
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Not that I know of. I don't even know of any of that orbital period where you can resolve both stars through a telescope. For such a short orbital period the two stars would have to be very close together. Somewhere on the order of 1 au or less, depending on the masses of the stars. There are no telescopes for visual observation able to resolve two stars that close.
 
Algol has a period just under 3 days. You cannot resolve the individual stars, but you can see the decrease in brightness - even with the naked eye - when the dimmer star eclipses the brighter. Algol goes from a bright second magnitude star to a relatively dim third magnitude star. This dim period lasts for 10 hours.
 
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thetexan said:
Are there any binary stars that can be seen with binoculars which have orbital periods you can observe from week to week or month to month?

Not that I am aware of ...unless they were substantially sized bino's ( haven't personally tried the BIG ones)

Alpha Centauri is easily split with a modest 6" reflector or a reasonable refractor ( been doing that and showing others since I was a kid)Dave
 
davenn said:
Not that I am aware of ...unless they were substantially sized bino's ( haven't personally tried the BIG ones)

Alpha Centauri is easily split with a modest 6" reflector or a reasonable refractor ( been doing that and showing others since I was a kid)Dave
Is it still possible?
Being the nearest binary, Alpha Centauri should be the easiest to see moving. (Any more distant, and a binary is either hard to resolve if short period, or slow moving if long period).
https://upload.wikimedia.org/wikipedia/commons/e/ee/Orbit_Alpha_Centauri_AB_arcsec.png
The separation of Alpha Centauri was at a global maximum around 1980. It is now near the local minimum. The global minimum is due in 2037.
Can you now, at the local minimum, resolve Alpha Centauri by binoculars, without excessive shaking?
 
snorkack said:
Can you now, at the local minimum, resolve Alpha Centauri by binoculars, without excessive shaking?

haven't tried over the last few years
I was looking at Alpha Cent. on Saturday nite with a group of people I took out for their first telescope and deep sky imaging session.
Used it as one of the 3 alignment stars for the GOTO scope. Looked at it so quickly, I cannot remember if I could split it or not.Dave
 
I calculated somewhat optimal conditions: let's imagine we would have two 100 solar mass stars orbiting each other at a distance of just 4 light years to us. We do not have those, of course. To get an orbital period of 1 month with circular orbits, the separation would be 1.1 AU, about 0.9 arcseconds in the sky. That still needs a telescope.

Edit: fixed missing factor of 2.
 
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