Home      Calendar      About OCA      E Zine      Resources      Image Gallery      Members
    www.ocastronomers.org/ e-zine/ monthly_meetings/ details /

OCA General Meeting
Friday September 18th, 2009, 7:30 PM
Chapman Universtiy
Free and open to public more

Helio Research

Sara F. Martin, a solar astronomer, is now President and Senior Scientist at Helio Research, a non-profit corporation founded in 1995 by Sara and her husband Douglas Martin along with other members of the board of directors. Sara has conducted much of her recent research using the 10-inch Martin telescope designed and built by Douglas, now retired from his former company, Spectra Optics. Sara also conducts collaborative research with an international team of solar astronomers who acquire data from an array of ground-based and space-based solar telescopes. Two findings in which Sara played a key role were the discovery of the counterstreaming in solar prominences and the roll effect in erupting prominences. These findings follow on earlier discoveries by Sara and colleagues showing that nearly every feature on the Sun has chirality or handedness including sunspots.

Helio Research Solar Observatory, La Crescenta, CA
This is a unique private 'one person' effort by Sara Martin to establish a simple observing facility for taking chromospheric observations of solar mass ejections, filament eruptions, and other solar activities. A 25-cm refracting objective is mounted on a peculiar equatorial mount, followed by a narrow band Lithium Niobate (LiNibO3) etalon filter and a CCD camera. Valuable scientific research data on solar mass ejections are being collected to understand the mechanism of filament eruption, CMEs (Coronal Mass Ejections) and solar geomagnetic effects. In Figure 2.4 is shown the equatorial solar spar telescope of Helio Research observatory, designed and built by Dong Martin.

The Three-dimensional Dynamic Structure of Solar Prominences
We can learn about the three-dimensional structure of solar phenomena from two dimensional images by several methods. The most direct technique is to use the fact that the Sun rotates on its axis at an average rate of 13 degrees per day. This allows us to view some solar phenomena from different perspectives if their duration is sufficiently long. Solar prominences are ideal subjects because their lifetimes range from less than a day for small prominences up to several weeks for large prominences. They are readily observed through small and large Earth-based telescopes using hydrogen alpha (Ha), calcium II (Ca II), and helium I (He I) filters. The term prominence historically has been used for observations of structures seen outside of the solar disk against the sky background. Specific sets of the same structures observed against the Sun's disk are now often called "filaments". A variety of solar prominences (filaments) seen from different viewing angles in Ha full-Sun images with low to medium spatial resolutions (in the range of 1-5 arc seconds) will be used to demonstrate the unique 3-dimensional overall structure of those prominences that correspond to filaments seen against the solar disk. High resolution but limited-field observations with spatial resolution down to 0.2 arc seconds reveal fine-scale threads in prominences (filaments) that are the building blocks of these intricate structures. Prominences and filaments are not static but consist of fine-scale flows along threads. Much of the volume of prominences and filaments consist of ribbons of closely-spaced, nearly parallel threads with interleaved flows in opposite directions by180 degrees. These basic properties of prominences (filaments) are shared by those in active regions, those on the quiet Sun and all intermediate ones. Doppler images in the light of Ha aid in seeing the threads with motions in our line-of-sight. Images in Helium II recorded by spacecraft experiments are especially helpful in detecting fainter parts of prominences (filaments) not fully seen in Ha. A few challenging observations and studies will be described that are within reach of amateur astronomers or small groups of amateur astronomers.

"What's Up?" in this month will be presented by Craig Bobchin

Pre-meeting Slide Show (~5 MB)
Club Announcements (~1 MB)

Previous Meetings

Copyright © 2001 - 2019 Orange County Astronomers
Bringing the universe into focus since 1967
About Us | Site Map | Contacts
Calendar | Gallery | General Meetings

amazon Amazon | OCAstroShop OCAstroShop | youtube YouTube | facebook Facebook | twitter Twitter | instagram Instagram