Indian astronomers spot over 200 new stars in the Pacman Nebula — and 51 of them are yet to reach adulthood

• Astronomers from the Aryabhatta Research Institute of Observational Science (ARIES) have discovered 228 new variable stars in the Pacman Nebula.
• The cosmic cloud of gas and dust is located 1,000 light years above the plane of the Milky Way offering a clear view of the star-making process,
• Among the collection of new stars, 51 haven’t reached adulthood yet — they’re still collecting gas and dust before they burst into the nuclear fusion of hydrogen.

Not every star shines bright in Earth’s sky. In fact, some of them are clearly visible one moment but dulled out in the next. These stars are called variable stars. And astronomers in India just spotted over 200 new ones in the Pacman Nebula.

The Pacman Nebula — officially known as NGC 281 — is around 9,500 light years from Earth, which is relatively close in the astronomical sense.


A team of astronomers, led by Sneh Lata of the Aryabhatta Research Institute of Observational Science (ARIES), set their sights on this cosmic cloud of gas using the largest reflecting telescope in Asia — the 3.6-metre Devasthal Optical Telescope (DOT). It is set up near Nainital in the Indian state of Uttarakhand.

And they managed to find 228 new variable stars. Out of these, 81 turned out to be cluster members. Stars within the same cluster are assumed to have formed at nearly the same time, from the same cloud, and with the same composition. The only difference between them is their mass.

The other 147 variable stars likely belong to the field population. They’re located in the same area as the cluster stars, but don’t necessarily share the same characteristics.


They found stars that are yet to become adults
Among the variable stars detected, 51 were pre-main-sequence (PMS) stars. This means they’re still in the early stages of their life, acquiring mass from the dust and gas that surrounds them.

They will only start burning hydrogen in nuclear fusion once they reach adulthood. Until then, they’re just gathering the resources they need.

Among these PMS stars, 30 are less than ten million years old, called T-Tauri stars. These are smaller than 2 solar masses. However, stars with a mass 2.5 times the size of the Sun were also present. These are called Herbig Ae/Be stars.

Stars get age spots too — and it affects the way they glow
The researchers found that the bigger the star, the smaller its amplitude. For a star, its amplitude is the range of its luminosity — the most bright and the dullest it can be.

According to the paper, the smaller aptitudes for larger stars could be due to the lack of material around them to chomp on or that distribution of spots on the photosphere — the outermost surface — of the stars is uneven.

And the variability of the amplitude also increases with age. This suggests that the distribution of spots on the surface of these variables changes with their age.

The Pacman Nebula has been key in examining the birth of stars and how they evolve. And it's unlike other star forming regions because it's located 1,000 light years above the plane of the Milky Way Galaxy. This means that astronomers have a nearly unfettered view of the star formation happening within.