<p><a href="https://i.sstatic.net/kjIy9.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/kjIy9.png" alt="Image of light curve of an eclipsing binary with description"></a></p>

<p>This light curve seems really weird to me, I'm used to seeing light curves where the barycenter is a straight line. It either stays at a place, moves at a constant speed or slowly increases its speed. But here it looks like the barycenter periodically changes its speed. Why is this happening? Can someone please explain the details of this graph.</p>

CC BY-SA 4.0
2018-07-29T19:39:44.730Z
Is there a third star in the system that could be causing additional fluctuations, or is it just these two stars?
HDE 226868
CC BY-SA 4.0
2018-07-30T07:21:30.007Z
As a minor bugbear, I'm used to a light curve being brightness vs time, so I wouldn't call this a light curve. That said, I'm with @HDE226868: it looks like there's a third body. I had thought that it might be something about the Earth's motion around the Sun but the period isn't right.
Warrick
CC BY-SA 4.0
2018-08-08T16:36:56.930Z
If there's a third body, it could be a supermassive blackhole. Or something really massive compared to the other two.
Arnab Chowdhury
CC BY-SA 4.0
2021-04-21T20:58:24.383Z
You question is about a screen shot of some source you haven't cited. Please retype the text as actual text so that the question is more easily searchable and vision-impaired community members can read it with a [screen reader](https://en.wikipedia.org/wiki/Screen_reader), and so that the context of the question can be researched by anyone interested. *Thanks!*
uhoh
<light-curve><time-domain-astronomy><eclipsing-star-systems>
Sinusoidal Light curve of an eclipsing binary
Arnab Chowdhury
# Sinusoidal Light curve of an eclipsing binary

(Asked by: username_0 on 2018-07-29)

[![Image of light curve of an eclipsing binary with description](https://i.sstatic.net/kjIy9.png)](https://i.sstatic.net/kjIy9.png)

This light curve seems really weird to me, I'm used to seeing light curves where the barycenter is a straight line. It either stays at a place, moves at a constant speed or slowly increases its speed. But here it looks like the barycenter periodically changes its speed. Why is this happening? Can someone please explain the details of this graph.

**Tags:** light-curve, time-domain-astronomy, eclipsing-star-systems
> **Comments:**
> **username_1**: Is there a third star in the system that could be causing additional fluctuations, or is it just these two stars?  
> **username_2**: As a minor bugbear, I'm used to a light curve being brightness vs time, so I wouldn't call this a light curve. That said, I'm with @HDE226868: it looks like there's a third body. I had thought that it might be something about the Earth's motion around the Sun but the period isn't right.  
> **username_0**: If there's a third body, it could be a supermassive blackhole. Or something really massive compared to the other two.  
> **username_3**: You question is about a screen shot of some source you haven't cited. Please retype the text as actual text so that the question is more easily searchable and vision-impaired community members can read it with a [screen reader](https://en.wikipedia.org/wiki/Screen_reader), and so that the context of the question can be researched by anyone interested. *Thanks!*  

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