I was answering a question about the Barr Effect on another sub, and I realized I can’t conceptualize what the effect translates to for us as observers. I’ll link the original post in a reply.
My understanding so far is that the Barr Effect was an observation that the longitude of periastron in spectroscopic binary systems was biased to be between 0-90 degrees.
I understand literally what it is, I think: the angle in the direction of motion between the ascending node and the point where the star in question is closest to the focus is biased to be between 0-90, but what does that translate to from our view point?
I was originally thinking it meant that the periastron of spectroscopically observed binary systems was biased to be further away from us, but I’m really not sure now.
My current explanation that I’m not sure is correct:
Since the Barr Effect is that most commonly observed angles are 0°-90°, it means that the point at which the stars are closest to each other tends to be *further* away from us, and also has a bias to be further away in one quarter of the orbit (rather than one half). The angle is defined in relation to the motion of travel, so 90° isn’t the same as 270°.
Picture a clock that you’re looking at directly. Between the 12 and the 3 is 0-90°. Now tilt that clock away from you so that the 12 is further away than the 6.
The Barr Effect says that the part where the stars are closest to the focus is likely to be in that 12- to 3-o’clock range.