Exploring Heliocentric Julian Day for Eclipsing Binaries Analysis

[Sastronaut]

Hi pf! I am working to better understand eclipsing binaries but to do so I need to understand a heliocentric Julian day; what it is and how it is advantageous for analyzing eclipsing binaries...could someone please explain to me how the Helio JD works and why its beneficial to use!? thanks!

 

[Drakkith]

Have you read the following article?
http://en.wikipedia.org/wiki/Heliocentric_Julian_Day

Also, see here: http://en.wikipedia.org/wiki/Barycentric_Julian_Date

 

[Sastronaut]

I have. I am still a little bit puzzled by it...

 

[Drakkith]

In what way?

 

[Sastronaut]

okay so the Heliocentric Julian Date (HJD) is the Julian Date (JD) corrected for differences in the Earth's position with respect to the Sun...but how is this beneficial when studying close orbiting eclipsing binary stars?

 

[Drakkith]

Say you take a few observations. Then you take a few more a month later. When you try to combine the data, you will find that the timing is off because of the extra distance the light has had to travel now that we are a month further along in our orbit. Using a heliocentric frame for timing, or better yet a baryocentric, would eliminate this timing error.