Monday, 11 September 2017
There’s one variety of solar prominence that I’ve been wanting to see for a long time. Even from before acquiring my first Hydrogen Alpha telescope. Coronal Loops.
I’ve been starved of any form of solar observing for a long time thanks to the terrible run of poor seeing conditions that have persisted over Sydney for several months. Even just at 50X magnification, the image of both the Sun and the Moon are unbearably shimmering. Yesterday I took a chance on a break in conditions, and boy, I was richly rewarded!
My first peak through the eyepiece saw my jaw hit the ground, and I started “Yahooing”! Coronal Loops! A big cluster of them too!
This is where another part of my fascination with astro kicks in. I did not know the name of this type of prominence, so if you don’t know something, you ask. I sent a text message to a fellow solar buddy of mine, Ivan, about the fabulous apparition. He was also kind enough to enlighten me on the association that these proms come from.
These are a rare prominence type, associated with highly volatile Active Regions on the Sun’s surface. Here, very high temperature plasma (atoms that are so hot they have been stripped of their electrons), is electrified and is racing along magnetic fields. These magnetic fields are also connected to areas containing Sunspots. Sunspots are a common feature on the Sun’s surface. However, Coronal Loops are not always present. They are only seen during periods of high activity, particularly during the Solar Maximum.
The Sun has been very subdued for a time, with very little prominence activity. These last few days has seen things take a major turn with not only several prominences appearing, but the Coronal Loops indicate a burst in activity.
This first sketch shows a complex set of Coronal Loops, erupting from several points.
Today, Ivan sent me a message to bust out the solar scope again. I couldn’t resist the suggestion. The Coronal Loops cluster had changed in appearance, and I just had to sketch this new apparition. There’s also two sets of sun spots that can be seen towards the bottom of these first two sketches. It can be seen the difference in the position of these two sets from one day to the next, indicating the rotation of the Sun during the 24 hour period.
The circumference of the sun was riddled with hedgerow proms, pillars, detached proms, pyramid proms, spicules, inclined proms, and one massive eruption. Along with the extraordinary Coronal Loops, the entire scene just demanded a sketch of the full disk – something I had not done before.
For my prominence sketches, I use a Quark Prominence filter on an ED80 refractor. While this filter is exquisite for prominences, details on the chromosphere are not particularly evident. These details are still there, but they take some doing to tease out. To help me tease out these details more easily, I use a little PST. This little scope allows me to quickly identify where significant chromosphere and then I use the Quark to pull out more detail from these specific areas. This way I was able to more easily identify where several filaments were, and another Active Region around a small group of sunspots.
It has been quite a wonderful return to solar sketching these last couple of days. From nothing for several months to three pieces that filled me with excitement. From very little solar activity, to a spectacular set of Coronal Loops and a massive eruption and an amazing collection of different prom types.
I hope you enjoy these three pieces too.