New massive stars to stir up galaxy
Three astronomers found the most numerous batch of young, supermassive stars yet observed in our galaxy, including several hundreds of the most massive kind - blue stars dozens of times heavier than our Sun.india Updated: Dec 02, 2011 13:20 IST
Three astronomers at the University of Toronto have found the most numerous batch of young, supermassive stars yet observed in our galaxy, including several hundreds of the most massive kind --blue stars dozens of times heavier than our Sun.
The light these newborn stars emit is so intense it has pushed out and heated the gas that gave them birth, carving out a glowing hollow shell about a hundred light-years across.
"By studying these supermassive stars and the shell surrounding them, we hope to learn more about how energy is transmitted in such extreme environments," said Mubdi Rahman, who led the work with his supervisors, Professors Dae-Sik Moon and Christopher Matzner.
Such large nurseries of massive stars have been noticed in other galaxies, but were so far away that all stars are often blurred together on images taken by telescopes.
"This time, the massive stars are right here in our galaxy, and we can even count them individually," Rahman said.
Studying the individual stars will require intricate measurements. The cluster of bright stars is located nearly halfway across our galaxy, 30,000 light-years away, and the line of sight is blocked by dust.
"All this dust made it difficult for us to figure out what type of stars they are."
The researchers used the New Technology Telescope at the European Southern Observatory in Chile to collect whatever light they could from a few dozen stars. They measured in details how much light the stars emit in each colour, and were finally able to confirm that at least a dozen stars in the cluster were of the most massive kind, some possibly a hundred times more massive than our Sun.
In fact, before turning a ground telescope toward the stars themselves, Rahman first noticed the glow from the large shell of heated gas using the WMAP satellite, which is sensitive to microwaves (between radio waves and visible light). To make an image of the gas shell being blown away and heated up, the researchers used the Spitzer satellite, which works with infrared light (between microwave and visible light).
Rahman suggested the name ‘Dragonfish’ after comparing the infrared image of the celestial gas shell with Peter Shearer’s illustration of the deep-sea creature with the same name.
The astronomical image resembles a dark gaping mouth-like shape with teeth, two eyes, and a bright fin to the right. The ‘mouth’ is the volume from which the gas has been cleared by the light of the stars, pushed outward to form a shell that is particularly bright in spots corresponding to the eyes and the fin of the animal.
“There may be newer stars already forming in the eyes of the Dragonfish,” Rahman added.
Some areas in the shell glow particularly bright, and the researchers think the gas there may have been compressed enough to ignite even more stars.
The study will be published in Astrophysical Journal Letters.