The origins of our Milky Way galaxy are now much clearer. Using a revolutionary “growth-chart,” scientists led by Melissa Ness of the Max Planck Institute for Astronomy in Heidelberg, Germany, discovered how our own Milky Way galaxy grew into what it is now.
They accomplished this by charting the ages of 70,000 stars and used that data to mock up a map for how the galaxy expanded and grew, Phys.orgstated.
“Close to the center of our Galaxy, we see old stars that were formed when it was young and small. Farther out, we see young stars. We conclude that our Galaxy grew up by growing out,” says Ness, lead author of the study. “To see this, we needed an age map spanning large distances, and that’s what this new discovery gives us.”
Scientists accomplished this by observing red giants in the inner and outer reaches of our galaxy. These stars are in the final stages of their lifespan. “If we know the mass of a red giant star, we know its age by using the fusion clock inside every star,” says Marie Martig, co-author of Ness’s study. “Finding masses of red giant stars has historically been very difficult, but surveys of the Galaxy have made new, revolutionary techniques possible.”
They did this by using spectra taken from one of the SDSS’s component surveys, titled the Apache Point Observatory Galaxy Evolution Experiment (APOGEE), the International Business Times reported.
“APOGEE is the ideal survey for this work because it can get high-quality spectra for 300 stars simultaneously over a large area of sky,” says Steve Majewski, Principal Investigator of the APOGEE survey. “Seeing so many stars at once means getting spectra of 70,000 red giants is actually possible with a single telescope in a few years’ time.”
As Steve Majewski said, this survey allowed them to map red giants across the galaxy. Although they could map red giants, the scientists couldn’t discover the ages of these stars through the survey alone — they had to use other data. In a brilliant move, the scientists studied light curves picked up from the Kepler satellite, a NASA space mission whose main goal is to find planets around stars.
These light curves allowed scientists to understand the ages of the red giants.
In summary, many of the red giants observed by APOGEE had also been observed by the Kepler satellite, allowing scientists to combine both sets of data to further understand our own universe.
“In the galaxy we know best – our own – we can clearly read the story of how galaxies form in a Universe with large amounts of cold dark matter,” says Ness. “Because we can see so many individual stars in the Milky Way, we can chart its growth in unprecedented detail. This unprecedented, enormous map really is one for the ages.”
It’s an interesting time in the world of space exploration and discovery. NASA recently released intentions to journey to Mars, according to the Wall Street Journal. Some estimates say that the first manned mission to Mars could take place around 2030.
Some say that extended manned missions to the moon could set up the building blocks to then reach Mars, but realistically this isn’t going to happen in the next decade.
For now, we get to celebrate the mapping of our own galaxy. Maybe someday soon mankind will be able to venture out into the far reaches of the Milky Way instead of just Mars.
[Image via Shutterstock]