Detection of Zeeman effect on AR 3014

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fulvio.mete
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Detection of Zeeman effect on AR 3014

Post by fulvio.mete »

I detected this morning on the two main components of the sunspot group AR 3014, with the spectrograph Hires Solarscan, the inverse Zeeman effect in non-polarized light, in order to measure the magnetic strength of the umbra of the spots.At a first glance, it does not seem to me that there are significant differences between the first component (marked as 1 in the image) and the second (marked as 2) despite the considerable greater extension of the first.This is possibly due to the fact that the first component of the group is very structured and consists of a set of small sunspots, while the second is much more compact, with a fairly well-defined umbra. I reserve further details, if possible.

Fulvio Mete
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Re: Detection of Zeeman effect on AR 3014

Post by p_zetner »

Very nice!
The Fe 6173A line exhibits the classic Zeeman triplet pattern and your spectrum (for the single spot) seems to give a clear splitting into the two sigma lines (in the penumbra). Why don’t you calculate the magnetic field?
Cheers.
Peter


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Re: Detection of Zeeman effect on AR 3014

Post by fulvio.mete »

Thanks, Peter:
I'll measure the splitting with Visual Spec (hoping to get two cusps in the spectral profile) as usual.Unfortunately the main component of 3014 (with multple spots) hasn't a clear umbra as the second.For this type of objects I'll need a long focal lenght telescope, instead the 355 mm of 60 mm Takahashi I use with Solarscan.

Fulvio


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Re: Detection of Zeeman effect on AR 3014

Post by fulvio.mete »

Hi, Peter, I evaluated the magnetic strenght of component 2 of 3014 sunspot group in 1683 Gauss, while that of component 1, much more extended, is only 1641 G.The reason of the apparent inconsistency is due, as I said before, to the fact the the slit did not cover all the umbral zone of component 1, as i tried to show in the attached image, based on a Hires shot of the group of this morning.
Cheers

Fulvio
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Re: Detection of Zeeman effect on AR 3014

Post by p_zetner »

Hi Fulvio.

These seem to be reasonable results. There is an empirical formula which relates the expected maximum field strength to the size of the spot (for isolated spots). The formula is given by Houtgast and van Sluiters (J.Houtgast and A.van Sluiters [1948] Bull.Astron.Inst.Netherl. V10, p235):

Bmax = 3.7A/(A+66) with sunspot area, A, in units of 1E-6 of the solar hemisphere and Bmax in kG.

You could measure the size (area) of the spot in component 2 and see if the measured field value is consistent with the prediction of the formula.

I’ve carried out an analysis of sunspot magnetic field using the Fe 6302.5 line:
https://www.cloudynights.com/topic/57 ... c-field/
The results were in line with predictions.

I’m planning to try the Mn 4070.3 line which is magnetically sensitive. I have a spectroheliograph now equipped with 3600 l/mm grating and measured spectral resolution of ~0.12 angstroms. Hopefully I can try this measurement out soon!

Cheers.
Peter


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Re: Detection of Zeeman effect on AR 3014

Post by fulvio.mete »

Hi, Peter, thanks for your interesting formula.
Your work on Fe1 6302 line was impressive: I downloaded it.
I made a report about Zeeman splitting in the Fe1 6137 A line in the main sunspots umbra of 2017 .
You'll find it here
http://www.lightfrominfinity.org/Osserv ... 202017.pdf
The Mn 4070.3 line sound interesting: what is its Landè factor?
Cheers

Fulvio


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Re: Detection of Zeeman effect on AR 3014

Post by Montana »

Wonderful results :hamster: very interesting :)

Alexandra


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Re: Detection of Zeeman effect on AR 3014

Post by fulvio.mete »

Thanks, Alexandra: it isn't an easy task, but worth it.

Fulvio


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Re: Detection of Zeeman effect on AR 3014

Post by p_zetner »

Hi Fulvio.

Sorry for the late reply to this post.
I read the document describing your Zeeman studies on sunspots and it was impressive! Very nice work.

As far as the Mn line at 4070 angstroms is concerned, the Lande g factor of this transition is 3.32 ... quite large. I made an attempt to examine this line on May 23 when there was a large spot present. Unfortunately, I captured a spectrum in the wrong spectral region by not setting my grating correctly! The blue / uv spectrum is very rich and my usual technique of setting the grating by visually comparing my observed spectrum with a BASS2000 or Liege spectrum failed. Have to be more careful and thorough next time!

I learned of the Mn line as a Zeeman splitting candidate from this paper - "Fraunhofer lines with large Zeeman splitting" by J. W. Harvey, Solar Physics volume 28, pages 9–13 (1973). The author presents a list of solar spectral lines having simple Zeeman triplet splitting with Lande g-factors equal to or greater than 2.5.

I've attached the list (Table III from the paper) below. With respect to the notation in the table, the product lambda*g is listed as a relative measure of Zeeman sensitivity since the Zeeman effect varies as lambda^2*g but line widths vary roughly as lambda. Line depth is measured in units of per cent of the continuum established from long wavelength intervals. Two numbers are listed; the first is the line depth referred to the continuum based on a long wavelength range and the second is estimated relative to the immediate wavelength range near the line. Blends are recorded as follows: 0 = no detectable blend, 1 = minor blending, 2 = significant blending, 3 = severe blend. The line strength in sunspots relative to the photosphere is listed, when possible, as: W = greatly weakened, w = slightly weakened, u = unchanged, s = slightly strengthened, S = greatly strengthened.

Hope you find this interesting / helpful.
Cheers.
Peter
Fraunhofer lines large zeeman splitting.jpg
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Re: Detection of Zeeman effect on AR 3014

Post by fulvio.mete »

Hi, Peter:
Thanks for reading my work, and thanks again for the suggestion of the Mn line at 4070.28 A: with a 3.32 Landè factor it should be possible for me to get a splitting of the line itself.I'll try it with POSS2, optimized for the near UV.The table with the sensitive Zeeman lines is a very interesting and helpful , for I had one similar, but for Iron lines only.

Cheers

Fulvio


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