MEXICO: The presence of stars just 100 million years old in the Milky Way Galaxy’s central regions confirms our galaxy’s nonviolent past.
If we could peer through all the dust and gas shrouding the Milky Way’s center, we’d find an oddly tasty sight: a Twinkie-shaped bulge. Like your typical Twinkie, the contents are fairly old (ok, the stars in the galactic bulge are a little older than the sweet cake, by 8 billion years or so). And like a Twinkie, it turns out, our galaxy’s bulge contains a surprising cream filling: a thin plane of very young stars.
István Dékány (Pontifical Catholic University of Chile) and colleagues found the plane when they discovered 35 Cepheid variable stars, each no older than 100 million years. The team will report the discovery in Astrophysical Journal Letters.
When Henrietta Leavitt discovered in 1912 that Cepheid stars pulsate with a beat directly related to their intrinsic brightness, she gave astronomers an invaluable tool: a distance measure. By watching a Cepheid’s brightness vary and comparing the variations’ timing to the star’s apparent brightness, astronomers use these stars to measure distances to stars far outside our galaxy.
Recently, Dékány’s team turned the power of Cepheids toward a problem closer to home: the hidden depths of our galaxy. Crowded with stars, gas, and dust, the central region of our pancake-shaped galaxy is hard to puzzle out in visible light. So the VISTA Variables in Vía Láctea (VVV) team, using the VISTA telescope in Chile, peers in infrared through the mist to look for Cepheid variables pulsing.
