Fw: Sun rotation project

["Bob Sciamanda" <trebor@velocity.net>]

Leigh asked:

> Perhaps you could help us by asking your colleague for help. Ask him if
> the H-alpha light he's observing in is within the Fraunhofer absorption
> linewidth. I'm betting it is.

> Leigh

Following is a forwarding of the reply I received from our campus
astronomer, Jim LoPresto, when I asked about the project which maps solar
rotation by observations of the H alpha line.

Bob Sciamanda   sciamanda@edinboro.edu
Dept of Physics   trebor@velocity.net
Edinboro Univ of PA  http://www.edinboro.edu/~sciamanda/home.html
Edinboro, PA   (814)838-7185


-----Original Message-----
From: Maize Sunfire <LOPRESTO@edinboro.edu>
To: trebor@velocity.net <trebor@velocity.net>
Date: Sunday, February 01, 1998 9:55 AM
Subject: Re: Sun rotation project


> That is an old project.  We are now doing a Solar Activity project and at
> Kitt Peak we are measuring wavlength shifts of closely spaced lines with
> very different excitation potentials or very different ionization
potentials
> using the 1 meter Fourier Transform Spectrometer.  The line are usually
> separated by 0.1 to 0.001 nanometers.  We are doing this over a range of
> both excitation and ionization potentials (although the latter are not as
> numerous as the former).  Then we apply a theoretical model of so called
> contribution functions to calculate the shape and details of the line
shapes
> with depth.  This presumably will provide us with more structural detail as
> a function of depth in both the photosphere as well as the chromosphere.
>
> We have already observed one thing we sort of expected.  Namely, the
> chromosphere in particular (having radiative temperatures in the range
> of about 15000 to 100000 Kelvins is highly non uniform.  This simply means
> that applying a simple height vs. depth model is at best highly wishful
> thinking.  The tops of these layers are the so-called transition region
> wherein over a small change in height the temperatues measured in a variety
> of ways spikes from the values above to coronal values in the millions and
> near condensations hundreds of millions.
>
> By the way one our main conclusions via our rotation project was that the
> Sun changes its rotation characteristics rapidly; e.g., the equatorial
speed
> can change by 5% in one day!  The polar swirls or solar polar vortex seems
> to come and go randomly?  The appears also to be a secular slow change in
> rotation vs. latitude that appears to be modulated by the solar cycle or
> the other way around?  The rapid changes cite above are probably caused by
> very thin "rivers", "streams" and "currents".  I find it hard to believe
that
> the Sun changes it angular momentum so rapidly.  These ideas have been in a
> general way confirmed by Helioseismolgy meaurements.
>
> Jim
>
> Dr. James C. LoPresto
> Observtory
> Edinboro University of PA
> Edinboro, PA 16444
> Phone: 814-732-2469