Our home galaxy is even more twisted than we thought. Astronomers have created a 3D map of the Milky Way’s disk revealing that it is warped, not flat.
To make the map, astronomers looked to its bright, pulsing stars called cepheids. These stars burn up to 10,000 times more brightly than the sun so they are visible from across the galaxy and through interstellar clouds of gas and dust. Crucially, cepheids are “standard candles”: Their light waxes and wanes at a rate that corresponds to their inherent brightness. Astronomers can combine their true brightness with their apparent brightness, measured from Earth, to calculate how far away they are. Using a 1.3-meter telescope at Las Campanas Observatory in Chile, astronomers monitored the steady pulses from more than 2400 stars and pinpointed their location on a 3D model of the galaxy.
The research, published today in Science, helps us see the galaxy in a whole new way. From above, the Milky Way can be seen as a spiral-shaped galaxy, but this spiral disk doesn’t sit flat on the galactic plane. The cepheid stars cluster along an S-shaped curve, showing that the Milky Way’s disk is more warped than previously thought. For many years, astronomers had to rely on measurements from other galaxies to infer the size and shape of the Milky Way. But new data, such as the cepheid map and billions of stars mapped by the European satellite Gaia, are helping astronomers find our place among the stars.