PARIS.- A new type of stars, which remain silent for long periods of time before exhaling a cloud of smoke, have just been detected by scientists.
“Old smokers”: that is the nickname of this new type of star, hidden in the heart of our galaxy, the Milky Way, according to a study published on Friday.
They are a new type of red giant stars, stars at the end of their life that acquire a large size and a low surface temperature at this stage.
They are very pale and reddish, to the point that “sometimes you can’t see them at all,” explains Dante Minniti from the Chilean Andrés Bello University, in a statement.
The peculiar exhalation of these stars had not been detected until now, adds astrophysicist Philip Lucas, in conversation with AFP.
The international team of scientists behind the discovery were not looking for old stars during their 10-year research, in which they analyzed hundreds of millions of stars across the sky, using the VISTA telescope in the Chilean Andes.
They were looking for newborn stars, called protostars, which are prone to frequent and exuberant eruptions.
They detected 32 protostars, “the largest number in a single group found so far,” said Lucas, a professor at the University of Hertfordshire in the United Kingdom and lead author of a new study.
But in the background there was a “pleasant surprise,” he added.
We don’t fully understand it
The “old smokers” were located near the center of the Milky Way, a densely populated, metal-rich region called the Nuclear Stellar Disk.
“The surprising thing about this new discovery is that we are seeing stars that were just sitting there doing nothing at all,” Lucas said.
Then, abruptly, the stars became 40 to 100 times dimmer, sometimes so faint that the telescope’s infrared vision could barely detect them.
A couple of years later, seemingly without warning, they returned to their former brilliance.
“Everything we’ve been able to find out about them suggests it’s a case of stars puffing out smoke, for reasons we don’t fully understand,” Lucas said.
These puffs of smoke are believed to temporarily obscure the stars from our view.
There are many other “heavy elements” — anything heavier than hydrogen and helium — in this region of the galaxy, which could create more dust in the star’s atmosphere, Lucas said.
What that powder is exactly remains a mystery.
But if this theory is correct, then the amount of matter ejected by these stars could play a significant role in how heavy elements are dispersed throughout our galaxy, and beyond, he said.
Lucas emphasized that these were just early assumptions.
“We’re just digging around to see what makes the most sense,” he said.
The researchers detected at least 21 “old smokers,” but they suspect there are many more.
The study was published in the monthly bulletin of the British Royal Astronomical Society.
Source: With information from AP
