Institute for Astronomy Solar-C

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Coronal Magnetogram | Dark Energy | Thermal IR Prospects | Prime Focus Instrumentation

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IfA Oahu | IfA Maui | Jeff Kuhn | Haosheng Lin | E. John Messersmith
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What We Are Currently Investigating

Recent Discovery

Jeff Kuhn and Haosheng Lin recently produced a "coronal magnetogram" - a map of the magnetic field in the corona using OFIS, After several hours of continuous observing, we achieved the sensitivity needed to detect the coronal magnetic field. The magnetic fields were measured about 62,000 miles (100,000 km) above the surface of the Sun, which is comparable in strength to what a compass needle feels on Earth's surface.

Coronal Magnetogram

In the winter of 2005, this article was phlished in the Na Kilo Hoku newsletter.


The Coronal "dark energy" Problem

A critical problem for understanding the solar corona has been to measure its magnetic field that we believe determines its structure and dynamics from the upper chromosphere out into the heliospheric environment. The direct measurement of this field has been a longstanding problem. Only recently have Zeeman splitting observations of infrared coronal emission lines (Lin et al. 2000) been used to deduce the coronal magnetic flux density. We have extended this technique and report here our first results from a novel coronal magnetometer that uses an off-axis reflecting coronagraph (SOLARC) and optical fiber-bundle imaging spectropolarimeter (OFIS). Our results reveal the line-of-sight magnetic flux density with a sensitivity of a few gauss with 20 arcsec spatial resolution and approximately 60min temporal resolution. These full Stokes spectropolarimetric data of the forbidden FeXIII emission line at 1075nm imply a line-of-sight coronal magnetic field above an active region with a flux density of 9G. Although these first results from SOLARC/OFIS have relatively coarse resolution, they have potential for solving our coronal "dark energy" problem with infrared magnetometry.

For more information click here.


Thermal IR Prospects for Coronal Magnetic Field Measurement

The SOLARC Haleakala reflecting coronagraph was designed and built for studying the IR solar corona. High dynamic range imaging and spectroscopy in the thermal IR offers unique prospects for coronal field measurements. Here we summarize the interesting opportunities, our progress and results toward this goal.

For more information click here.


Strategies for Prime Focus Instrumentation in Off-axis Gregorian Systems

A new generation of off-axis telescopes has been proposed to address a number of high dynamic range problems in astrophysics. These systems present unusual problems and opportunities for the instrument designer. We will discuss some of the issues that must be resolved when placing instrumentation at the prime focus. The heat stop and occulter systems for the SOLARC off-axis coronagraph will be used to illustrate strategies for solar telescope applications.

For more information click here.

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