Astronomers in Brazil have discovered a cluster of stars in the very stages of formation on the edge of the Milky Way, according to a press release from the Royal Astronomical Society. Denilso Camargo of the Federal University of Rio Grande do Sul in Porto Alegre, Brazil lead the team, whose results were published in the journal Monthly Notices of the Royal Astronomical Society.
Our galaxy is a spiral galaxy with stars, gas and dust swirling outward from a central bar. If viewed from the side, the galaxy would appear to be a slim disc. Giant molecular clouds (GMCs) are breeding grounds for new stars and are mostly found in the inner area of the disc. Stars are typically born in clusters due to the grouping of gas in the GMCs.
Camargo and his colleagues used data from NASA's orbiting Wide-Field Infrared Survey Explorer (WISE) observatory and found GMCs thousands of light-years above and below the galactic disc, according to the press release. One of the GMCs contained not one, but two, star-baby making clusters. Astronomers had never before seen the birth of stars in a location so far away from the inner sanctum.
Camargo 438 and 439, the new clusters, are part of molecular cloud HRK 81.4-77.8. HRK 81.4-77.8 is believed to be 2-million-years-old and is around 16,000 light-years beneath the galactic disk - which is quite remote for star formation.
There are two explanations for the distant location of clusters, according to the press release. One relates to the Chimney Model in which violent happenings, like supernova, cause explosions that eject gas and dust out of the disk. When the material falls bac, a GMC is formed. The second idea suggests that the Milky Way and its satellites, the Magellanic Clouds, disturbed gas that was falling into the galaxy, thus forming a GMC on the edge.
"Our work shows that the space around the galaxy is a lot less empty that we thought," Camargo said, according to the press release. "The new clusters of stars are truly exotic. In a few million years, any inhabitants of planets around the stars will have a grand view of the outside of the Milky Way, something no human being will probably ever experience."
"Now we want to understand how the ingredients for making stars made it to such a distant spot," he continued. "We need more data and some serious work on computer models to try to answer this question."
The research was also conducted by Eduardo Bica, Charles Bonatto and Gustavo Bonatto, of the Federal University of Rio Grande do Sul and Colégio Militar de Porto Alegre -- Exército Brasileiro. The paper is titled, "Discovery of two embedded clusters with WISE in the high galactic latitude cloud HRK 81.4-77.8" and authored by D. Camargo, E. Bica, C. Bonatto, and G. Salerno.
