Eclipsing Binaries

[eosophobiac]

I've been reading up on binaries, and was struck by one segment that stated that the brightness of an eclipsing binary will lessen as the companion star passes in front of or behind the primary star. I can understand why the brightness would be less as the companion passed in front, but I'm wondering why/how the brightness would be affected when the companion passed <b>behind</b> the primary star..? Can anyone explain to an amateur, and use little words, why this is?<br />Thanks! <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[yevaud]

It's extraordinarily rare for coupled binaries to be the same size/mass. One is usually larger than it's companion.<br /><br />When one passes in front of or behind the other, it's occluded by the other. So you get a sinewave of increasing/decreasing output of light. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[eosophobiac]

Thanks for that, Yevaud. You used those small words that I could understand, and somewhere in the back of my mind, it seems I should've known what you explained. It makes sense. I just kept thinking (not!) as I was reading that the stars would be about the same size, and now realize the likelihood of that happening is pretty small.<br />Thanks again. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

 

[yevaud]

Np. Btw, as a small thought experiment, imagine holding a softball in front of you, with a golf ball rotating around it. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[Leovinus]

Three cases to consider. <br /><br />1) stars are side-by-side. In this case, we get light from both.<br /><br />2) smaller behind bigger. In this case, we get light only from bigger one.<br /><br />3) bigger behind smaller. In this case, we get all light from smaller and not all of the light of the bigger.<br /><br />As you can see, no matter which star is in front of the other, you it won't be as bright as if the stars are side-by-side. <div class="Discussion_UserSignature"> </div>