Image: European Southern Observatory
Astronomers are particularly interested in the life cycle of massive stars like the Pistol Star because these giants, with their powerful radiation fields and stellar winds, heavily influence the happenings in normal galaxies. The only problem is finding them. Though enormous, these stars are rare and flash through life much more quickly than lighter lights. And although their deaths arrive in violent supernovas, their younger years--like those of lighter stars--cannot be seen in visible wavelengths.
But the Son of Isaac (SOFI) instrument at the New Technology Telescope at La Silla Observatory recently spied a few nursing giants within Messier 17, also known as the Omega, Swan, Horseshoe or Lobster Nebula--depending on how you interpret its outline in visible light. This region is some 5,000 light-years away from us and appears in the southern constellation of Sagittarius. In the SOFI near-infrared image above, captured by Italian scientists Leonardo Testi and Leonardo Vanzi, the young and heavily obscured stars are recognized by their red color. A cluster of them appears toward the upper-left corner. Bluer objects are either foreground stars or well-developed massive stars. And the diffuse light in the photo results from protons and electrons recombining into hydrogen atoms.