A clever trick to cook young stars discovered for the first time – astronomers highlight magnetic field as missing ingredient

For the first time, astronomers have discovered the missing ingredient to cook stars in the same way you would steam a Christmas pudding. Just as a pressure cooker has a weight on its lid that maintains pressure to make a festive dessert rich and moist, so galaxies merge to create ideal conditions for star formation. may require a magnetic field.

However, until now, the existence of such forces has not been observed, but only theorized.

An international research team led by Imperial College astrophysicist Dr David Clements has discovered evidence of a magnetic field associated with a disk of gas and dust hundreds of light years across deep within two merging galaxies known as Arp220. .

They say these regions could be the key to cooking the centers of interacting galaxies with large amounts of hydrogen gas, making them suitable for young stars. This is because the magnetic field could effectively prevent the intense burst of star formation at the center of a merging galaxy from “boiling” if it gets too hot.

A new paper revealing the discovery has been published in Monthly Notices of the Royal Astronomical Society.

“This is the first time we’ve found evidence of a magnetic field at the center of a merger,” Dr. Clements said. “But this discovery is just a starting point. We now need better models, and we need to see what’s happening in other parts of galaxy mergers.” ”

He used a cooking analogy to explain the role of magnetic fields in star formation.

“If you want to make a lot of stars (Christmas puddings) in a short period of time, you need to squeeze a lot of gas (or material) together. This is what we see at the core of mergers. But then you can make young stars (Christmas puddings). or the rice cooker) can build up and boil, causing the gases (or the pudding mixture) to disperse,” Dr. Clements said.

“To stop this, we need to add something to hold everything together, like a magnetic field within the galaxy or a pressure cooker lid and weight.”

Astronomers have long searched for the magic ingredient that allows some galaxies to form stars more efficiently than normal.

One of the problems with galaxy mergers is that they can form stars very quickly, in a phenomenon known as starbursts. This means that the relationship between the star formation rate and the mass of stars within the galaxy behaves differently from other star-forming galaxies, and it is more efficient than galaxies other than starburst galaxies. It seems to be turning into a star. Astronomers are puzzled as to why this happens.

One possibility is that the magnetic field acts as a special “binding force” that holds the star-forming gas together longer, resisting its tendency to expand and dissipate as it is heated by young, hot stars or supernovae. This means that there is a possibility of doing so. Massive stars die.

Theoretical models have previously suggested this, but the new observations are the first to show that a magnetic field is present in at least one galaxy.

Researchers used the Submillimeter Array (SMA) on Mauna Kea, Hawaii, to probe deep inside the ultra-bright infrared galaxy Arp220.

SMA is designed to take images of light at a wavelength of about 1 millimeter, at the border of infrared and radio wavelengths. This opens the door to a wide range of astronomical phenomena, including supermassive black holes and the birth of stars and planets.

Arp220 is one of the brightest objects in the extragalactic far-infrared sky, resulting from the merger of two gas-rich spiral galaxies, which triggered starburst activity in the core region of the merger.

The extragalactic far-infrared sky is the cosmic background radiation, consisting of integrated light from dust emissions in distant galaxies. About half of all starlight appears in far-infrared wavelengths.

The team’s next step is to use the Atacama Large Millimeter/Submillimeter Array (ALMA), the most powerful telescope for observing molecular gas and dust in the cold universe, to study other ultra-bright infrared galaxies. It’s about exploring magnetic fields.

That’s because the next brightest local superluminous infrared galaxy after Arp220 is more than a quarter fainter.

The researchers hope that their results and further observations will shed more light on the role of magnetic fields in some of the brightest galaxies in the local universe.