NASA's Hubble Space Telescope has discovered the early "blueprints" of our galaxy in the Milky Way's central hub of stars.
The telescope revealed a collection of white dwarfs, which are the remnants of dying stars, deep within the Milky Way's core, NASA's Goddard Space Flight Center reported. These findings could help solve the mystery of how our galaxy evolved before the Earth and the Sun existed.
The Hubble observations are the most detailed look we have ever gotten at the Milky Way's central bulge. The white dwarfs contain information about stars that existed 12 billion years ago. The analysis supports the idea that the central bulge formed only about two billion years before its inhabitant stars were born; the sprawling disc and outside stars are believed to have formed much more slowly.
"It is important to observe the Milky Way's bulge because it is the only bulge we can study in detail," said Annalisa Calamida of the Space Telescope Science Institute (STScI) in Baltimore, Md. "You can see bulges in distant galaxies, but you cannot resolve the very faint stars, such as the white dwarfs. The Milky Way's bulge includes almost a quarter of the galaxy's stellar mass. Characterizing the properties of the bulge stars can then provide important information to understanding the formation of the entire Milky Way galaxy and that of similar, more distant galaxies."
Hubble also spotted two low-mass stars, suggesting that the environment and star formation mechanisms of the central bulge were once different than what was seen in the surrounding disc.
"These 70 white dwarfs represent the peak of the iceberg," said Kailash Sahu of STScI. "We estimate that the total number of white dwarfs is about 100,000 in this tiny Hubble view of the bulge. Future telescopes such as NASA's James Webb Space Telescope will allow us to count almost all of the stars in the bulge down to the faintest ones, which today's telescopes, even Hubble, cannot see."
The findings were published in a recent edition of the Astrophysical Journal.
