spectro-aras.com

Hello at all,

Led by Gary Cole who has been dedicating almost part of his life to stellar polarimetry, I show here a spectro-polarimeter sketch that I'll try to build during this year.

If you see C. Buil's website, you will realize that this isn't the first attempt to connect this "new" observational specialty.

The main aim is to fill an important gap in the stellar study.

This way are plenty of doubts and unknowns, that is only the beginning, then we'll see.

Having projects helps to have good feelings.

Your opinion is very important to me.

Cheers, Joan.

Hello Joan

I don't know which of Christian's pages you're referring to, but to do spectropolarimetry you need to use a high-resolution spectrograph (> R=20000) to see the Zeeman effect, for example.

And you need to be able to turn the 1/4-wave plate during acquisition to obtain various polarization values:

See Christian's setup here :
http://spectro-aras.com/forum/viewtopic.php?t=1680

And Guillaume Bertrand's article adapted to a Star'Ex HR :
https://www.shelyak.com/spectropolarime ... ime-en-3d/

Many year ago, I've also done some tests with Daniel Verilhac and a whoppshel spectrograph R=30000

FIGU eshel equip with a left circular and right circular polariser



and the result with Cor Carolie for the Zeeman effect.



So spectropolarimetry for amateur il only dedicated to very bright target (to have a very good SNR).

Bonjour Olivier,

How are things going?

Many thanks for all your explanations and help, I'll be on account for them.

If my memory doesn't fail, C.Buil had to make something with a LISA spectrograph.

You know that I'm only an, - few times a good -, observer and I don't know anything about reduction data and astrophysics matters, but it seems that this project of a low-resolution spectro-polarimeter had interested to three university doctors in physics, - they don't know each other -, I don't know why about this interest.

The first one of three has been working and taking precious data for a lot of years in low-resolution, and the other two are looking forward to this data in their different types of star studies.

Also, there exists the aeronautical possibility that all of them are wrong too.

So a practical solution is to make one low-resolution spectro-polarimeter and see if all of it works, we'll see.

At the moment, I'm going to send them this link with your interesting explanations.

Best regards, Joan.

Hola Joan,

I think the page you are referring to on LISA in polarimetric spectro is this one:
http://www.astrosurf.com/buil/polar4/

Of course, the Zeeman effect isn't measured in this case, so it's accessible at low resolution, but on luminous targets because the variations to be measured are of the order of 1% between different polarizations, so quite low and requiring a very good SNR. Not to mention that the spectro needs to be very stable from one measurement to the next (by changing polarization orientation) to obtain the various I, Q and U parameters.

But I'm curious about what your three university doctors in physics wanted to mesure ?

Hi Joan !

Very interesting all that
I am a fan of spectro polarimetry Polarization is a fascinating property of light. Too bad this field is not explored more by amateurs.
After some convincing tests in high resolution on circular polarization (see the link given by Olivier above or this one https://guillaumebertrand.notion.site/S ... c46c4adea9)
I have been actively working for several months on linear polarization in low resolution with a Newton 150 and a Star'Ex 300l/mm. It is more difficult for me! The mediocre and very variable weather of the last few months really does not help... Christian had really done a great job with his LISA.

Bonjour Olivier et Guillaume,

I'm very impressed with your work and knowledge about spectro-polarimetry, it's a sample of the growing interest in this specialty during the last few years. And you are dedicating effort and time to it.

In my case, under indications. tips, advice, etc. I only have designed this low-resolution spectro-polarimeter to achieve some analysts' demands.
As said, I don't know anything about their data reduction, application, or their analysis.

It's beginning its construction phase, so it rests for many months before its first light, then I will be able to bring useful polarimetric spectra to the faintest possible magnitude.

In addition, it is possible that if the observations fulfill the standard requirements, their demand will grow progressively.

We have to give time to time.

Cheers, Joan.

Hello,

These are the last sketches.

Joan.

Hello,

Two modules are finished, without the optics, of course.

J.G.

Hello,

This is a picture from 27 08 2024. Slowly the container is growing.

Joan.

Hello,

This is the current state.

JG.