'Green Pea' galaxies' mystery unveiled
An astronomer has unveiled the mysteries of the so-called ‘Green Pea’ galaxies. These newly-discovered galaxies appear to be compact low-mass galaxies undergoing intense star formation.india Updated: Sep 11, 2010 14:30 IST
An astronomer has unveiled the mysteries of strange so-called ‘Green Pea’ galaxies.
First discovered in 2007 by amateur stargazers, it has now been shown that these extraordinary and extremely compact star cities have low amounts of complex elements after being diluted by streams of gas and strong supernova winds.
And the latest announcement will trigger celebrations among amateurs who first discovered Green Pea galaxies.
Ricardo Amorin will present a talk explaining the nature of strange so-called Green Pea galaxies.
“This Green Pea discovery is a fabulous example of how normal citizens, ‘astronomy lovers’, can help scientists with their collective efforts. They discuss the science with professional astronomers, and have written an excellent Wikipedia entry about Green Pea galaxies which presents a lot of information to people of the world,” said lead scientist Ricardo Amorin.
Green Pea galaxies were first classified by hobby stargazers.
The online project Galaxy Zoo and Galaxy Zoo 2 asked interested members of the public to help sort through a vast depository of night sky images produced by the Sloan Digital Sky Survey.
Categorizing galaxy types is both important to learn about the evolution of the Universe, and also difficult because of the ambiguous shape of many.
Astronomers turned to the online community for help, and citizen scientists flocked to sift through the images and look for galaxy types.
Within 24 hours of launch the site was receiving an astonishing 70,000 classifications an hour.
These citizen scientists discovered a strange type of galaxy that did not fit with previously known types.
Small in size and green in colour, they were soon named “Green Pea” galaxies.
They appear to be compact low-mass galaxies undergoing intense star formation, and being around 1.5 to 5 billion light-years distant indicates that this is a brief but extreme stage of their evolution.
Green Pea galaxies are now known to be “metal-poor”; metals in this astronomical sense meaning any element other than hydrogen and helium.
The latest study suggests that gas gravitationally attracted from the outskirts of the Green Pea galaxies or beyond, combined with shockwaves from supernova explosions, are likely causes.
Amorin explained: “Discovering Green Pea galaxies has opened a new window to investigate galaxy evolution and star formation in the early Universe.”
“The Galaxy Zoo volunteers have put science very close to the citizens. This is an active and powerful way to spread science,” concluded Amorin.
The latest incarnation of Galaxy Zoo uses data provided by the famous Hubble Space Telescope, to peer deeper into the Universe than before.
The findings of the study were presented at the Joint European and National Astronomy Meeting (JENAM 2010).