Australian Students and Gemini Observatory
Remember back when you entered the science fair at school? I remember a winning entry that I did — something about yeast that my mother helped cook up. I didn’t get to go get my ribbon for that one because I was at home with measles. Nowadays, kids get vaccinated for measles (the smart parents all do this), and so having spotty bumps on one’s skin is no excuse for missing out on a science fair award.
A group of students from Sydney Girls High School in Australia went way beyond science fair with their idea — to use Gemini Observatory to study a pair of interacting galaxies called NGC 6872 and IC 4970. They were participating in a country-wide contest to suggest scientifically interesting and aesthetically pleasing objects for the observatory’s telescope to snare with its 8-meter mirror.
The contest sponsors liked their proposal so much that it was selected as the winner, and the image at right was the result. The main instrument used to make this image was the Gemini Multi-Object Spectrograph (GMOS), in its imaging mode on the Gemini South telescope in Chile.
The primary galaxy in the image (NGC 6872) shows what happens when galaxies interact and their original structure and form is distorted. When galaxies like these get too close to each other, the mutual gravitational pull starts to distort their structures. Their spiral arms get stretched out to enormous distances, with streamers of starburst knots following along. In NGC 6872, the arms have been stretched out to span hundreds of thousands of light-years—many times further than the spiral arms of our own Milky Way galaxy.
Over hundreds of millions of years, NGC 6872’s arms will fall back toward the central part of the galaxy, and the companion galaxy (IC 4970) will eventually be merged into NGC 6872. The coalescence of galaxies often leads to a burst of new star formation. Already, the blue light of recently created star clusters dot the outer reaches of NGC 6872’s elongated arms. Dark fingers of dust and gas along the arms soak up the visible light. That dust and gas is the raw material out of which future generations of stars could be born, and possibly even countless numbers of planets.
The search for these dynamic changes in galaxy structure was what sold the selection committee on the students’ observation proposal. They wrote, “If enough color data is obtained in the image it may reveal easily accessible information about the different populations of stars, star formation, relative rate of star formation due to the interaction, and the extent of dust and gas present in these galaxies.”
The team also presented a more emotional perspective by looking at the impact this image might have on people trying to understand our place in the universe. When viewers consider this image “in contrast to their daily life,” the team explained, “there is a significant possibility of a new awareness or perception of the age and scale of the universe, and their part in it.”
When I look at this picture, I really envy those kids. Imagine getting to have your science project executed on one of the world’s premier telescopes!