The center of the Milky Way is the most prolific star-forming region in the entire Galaxy.
However, astronomers have only found a fraction of the young stars they expected here: there is ‘fossil’ evidence that many more stars were born in the recent past than the ones we actually see.
This is because looking towards the center of the Milky Way is not an easy task: clouds of dust and gas block the light from the stars and obscure the view.
“The Galactic center stands out as the most prolific star-forming environment of the Galaxy when averaged over volume,” said Dr. Francisco Nogueras Lara, an astronomer at ESO.
“In the last 30 million years, it has witnessed the formation of around one million of stars.”
“However, crowding and high extinction hamper their detection and, up to now, only a small fraction of the expected mass of young stars has been identified.”
Dr. Lara aimed to detect hidden young stars at the Galactic center by studying the stellar population in Sagittarius C.
In the study, he analyzed data from the HAWK-I infrared instrument on ESO’s Very Large Telescope.
He found that Sagittarius C was much richer in young stars than other areas in the Galactic center.
“We find that Sagittarius C hosts several hundreds of thousands of solar masses of young stars,” Dr. Lara said.
“We compared our results with the recently discovered young stellar population in Sagittarius B1, which is situated at the opposite edge of the nuclear stellar disk.”
“We estimated that the Sagittarius C young stars are around 20 million years old, and likely show the next evolutionary step of the slightly younger stars in Sagittarius B1.”
“Our findings contribute to addressing the discrepancy between the expected and the detected number of young stars in the Galactic center, and shed light on their evolution in this extreme environment.”
“As a secondary result, we find an intermediate-age stellar population in Sagittarius C (around 50% of its stellar mass with an age of between 2 and 7 billion years), which is not present in the innermost regions of the nuclear stellar disk (dominated by stars older than 7 billion years).”
“This supports the existence of an age gradient and favors an inside-out formation of the nuclear stellar disk.”
The findings appear in the journal Astronomy & Astrophysics.
F. Nogueras-Lara et al. 2024. Hunting young stars in the Galactic centre. Hundreds of thousands of solar masses of young stars in the Sagittarius C region. A&A 681, L21; doi: 10.1051/0004-6361/202348712