Celestia Forums

First orbit measurement of eclipsing binary in Andromeda!
========================================

This could be fun to implement in Celestia and is also of considerable astrophysical interest:

Published in the Astrophysical Journal 2006, here is the respective paper :

http://arxiv.org/pdf/astro-ph/0511045

Title:

First Determination of the Distance and Fundamental Properties of an Eclipsing Binary in The Andromeda Galaxy

--------------------------------------------
Abstract:

We present the first detailed spectroscopic and photometric analysis of an eclipsing binary in the Andromeda Galaxy (M31). This is a 19.3-mag semi-detached system with components of late-O and early-B spectral types. From the light and radial velocity curves we have carried out an accurate determination of the masses and radii of the components. Their effective temperatures have been estimated from the modeling of the absorption line spectra. The analysis yields an essentially complete picture of the properties of the system, and hence an accurate distance determination to M31. The result is d=772+/-44 kpc ((m-M)_0=24.44+/-0.12 mag). The study of additional systems, currently in progress, should reduce the uncertainty in the M31 distance to better than 5%.
-------------------------------------

They give all needed orbit parameters in the paper, hence I could easily convert the data to Celestia frame data with my PERL code.

Would be cool to watch a binary system orbiting within my nice Andromeda galaxy setting

Bye Fridger

Also an eclipsing binary in Triangulum:

http://arxiv.org/abs/astro-ph/0606279

Title:

The First DIRECT Distance Determination to a Detached Eclipsing Binary in M33

--------------------------------------------
Abstract:

We present the first direct distance determination to a detached eclipsing binary in M33, which was found by the DIRECT Project. Located in the OB 66 association at coordinates (alpha, delta)=(01:33:46.17,+30:44:39.9) for J2000.0, it was one of the most suitable detached eclipsing binaries found by DIRECT for distance determination, given its apparent magnitude and orbital period. We obtained follow-up BV time series photometry, JHKs photometry and optical spectroscopy from which we determined the parameters of the system. It contains two O7 main sequence stars with masses of 33.4+/-3.5 Mo and 30.0+/-3.3 Mo and radii of 12.3+/-0.4 Ro and 8.8+/-0.3 Ro, respectively. We derive temperatures of 37000+/-1500 K and 35600+/-1500 K. Using BVRJHKs photometry for the flux calibration, we obtain a distance modulus of 24.92+/-0.12 mag (964+/-54 kpc), which is ~0.3 mag longer than the Key Project distance to M33. We discuss the implications of our result and the importance of establishing M33 as an independent rung on the cosmological distance ladder.
--------------------------------------------

Again, the parameters of the binary are given.

Time to smash the 16kly limit?

chaos syndrome wrote:
Time to smash the 16kly limit?

RIGHT...

Bye Fridger

chaos syndrome wrote:Time to smash the 16kly limit?

We need to =\

Hungry4info wrote:

chaos syndrome wrote:Time to smash the 16kly limit?

We need to =\

But I doubt it'll happen for a loong while.

Hi

Just a question: How did you passed the 16 kyr limit? I still don't understand it.

starcreator wrote:Hi

Just a question: How did you passed the 16 kyr limit? I still don't understand it.

The 16k ly limit in Celestia was a precision issue. Now distances between stars and the observer are calculated at high precision which is enough to fix the problem.

You might perhaps be interested also in my thread "Games with Orbiting Stars in Alien Galaxies..." over in our CelestialMatters site. It's from past fall...

http://forum.celestialmatters.org/viewt ... 10&start=0

There I coded a bunch of stars encircling the Black Hole in the center of our galaxy as well as lots of moving stars over in M 31 (Andromeda).

In this thread, I made some cute videos, too, which you may have to download first depending on your line speed. They are 1024 pixels wide...

Fridger

Another one of these nice extragalactic eclipsing binaries with distance determination: OGLE-051019.64-685812.3 which consists of two G-type giants.

Another eclipsing binary in Andromeda

Incidentally the binary referred to by Fridger in the first post of the thread is now referred to as M31V J00443799+4129236 instead of M31V J0044380+41292350... the perils of coordinate-based designations!