Stars are born from big clouds of principally hydrogen fuel floating in area. Astronomers like me examine this fuel as a result of it helps us perceive how stars and galaxies kind and develop.
Hydrogen fuel provides off a faint glow that’s invisible to human eyes however will be noticed with a telescope tuned to detect radio waves.
Not too long ago, my colleagues and I had been utilizing a telescope like this – a radio telescope referred to as MeerKAT, in South Africa – to search for hydrogen fuel in a selected galaxy. We had been solely observing for lower than three hours, which is kind of a brief period of time for the reason that hydrogen glow is so faint.
After we appeared on the outcomes, we had been in for an enormous shock. As an alternative of discovering hydrogen fuel within the galaxy we aimed toward, we noticed it in a minimum of 49 beforehand unknown galaxies. Our findings are revealed within the Month-to-month Notices of the Royal Astronomical Society.
Gasoline in galaxies
The enormous clouds of fuel through which stars are born are referred to as nebulae. When stars ultimately die, they expel their fuel into their surrounding setting, the place it will definitely cools and types new nebulae.
Galaxies are like big factories the place the life cycle of stars repeats itself time and again. To correctly perceive galaxies and the way they develop and evolve, astronomers want to contemplate each the celebs and the fuel making up the galaxy.
One factor we’re significantly excited by is “merger occasions”, when two galaxies collide and merge right into a single, bigger galaxy. These occasions may affect the fuel, and kickstart star formation.
Learning fuel can typically assist us perceive a galaxy’s historical past. Gasoline typically extends far additional out than the celebs in galaxies.
After we see trails of disturbed fuel, it’s a basic clue {that a} latest galaxy merger or interplay has occurred.
However we don’t see galactic fuel simply with optical telescopes. Fortunately, radio telescopes are an ideal device for locating hydrogen fuel.
The MeerKAT radio telescope, made up of 64 radio dishes working collectively to behave as a bigger telescope.
South African Radio Astronomy Observatory (SARAO)
The MeerKAT radio telescope
The MeerKAT radio telescope in South Africa not too long ago celebrated its fifth birthday. It is likely one of the “pathfinder” telescopes for the a lot bigger Sq. Kilometre Array (SKA), a venture below building in South Africa and Australia.
MeerKAT has already achieved some nice outcomes, from detecting big radio galaxies to learning the centre of our personal galaxy, the Milky Method.
There are giant survey initiatives underway with MeerKAT to check the star-forming hydrogen fuel in galaxies. These embody the MIGHTEE-HI and LADUMA surveys, the latter of which can use MeerKAT for greater than 3,000 hours looking out one a part of the sky for hydrogen fuel in very distant galaxies. These surveys are particularly centered on discovering hydrogen fuel and are fastidiously deliberate and carried out with that aim in thoughts.
However that’s not the one method MeerKAT can be utilized. Astronomers may pitch concepts for “open time” observations to sort out different science questions or targets.
That’s how this discovery took place. I hoped to detect hydrogen fuel in a single particular galaxy with MeerKAT, as it’s the most delicate telescope for these research.
We didn’t discover hydrogen fuel in that galaxy, which was positive. We astronomers don’t all the time discover what we’re in search of.
However once I inspected the MeerKAT knowledge, I noticed some fuel situated away from the goal galaxy. So we investigated additional.
Through the use of methods developed for the bigger MeerKAT science surveys comparable to LADUMA, we discovered much more fuel. In complete, we had 49 detections.
The 49 new gas-rich galaxies detected by the MeerKAT radio telescope in South Africa. Every detection is proven as colored contours, with redder colors indicating extra distant fuel from us, and bluer colors as nearer fuel. The background picture comes from the optical PanSTARRS survey.
Glowacki et al. 2024
Meet the 49ers
Every detection of the fuel in these galaxies was model new. In little greater than two hours of observing time, MeerKAT had revealed a number of collections of neighbouring galaxies.
A few of these neighbours are even interacting with one another, as their fuel content material reveals. This was under no circumstances apparent from simply trying on the optical pictures of their stars.
In a single case, a galaxy is stealing fuel from two companion galaxies, and utilizing it to gasoline its personal star formation.
Examples of particular person detections of the fuel detected by MeerKAT (white contours) on high of a three-colour optical picture from the DECaLS DR10 survey. The fuel seen right here extends additional out than the celebs within the galaxies.
Glowacki et al. 2024
I’ve informally nicknamed this assortment of galaxies the 49ers, a reference to the miners of the 1849 California gold rush.
Whereas MeerKAT took the observations containing the 49 gold nuggets in simply a few hours, winnowing them out required a number of different instruments. These included the ilifu cloud supercomputer, the place we diminished the MeerKAT observations (“knowledge discount” is a form of pre-processing that makes the uncooked observations helpful) and a knowledge visualisation device referred to as CARTA which we used for the preliminary discovery of the 49 new galaxies.
We additionally examined our knowledge with iDaVIE-v, a digital actuality software program for viewing astronomical datasets in 3D. This software program has already been used for brand spanking new discoveries comparable to polar ring galaxies.
VR view of a number of “49er” gas-rich galaxies.
VR view of a zoom-in of the 49er galaxies.
Extra gold nuggets to be discovered
Discovering 49 new galaxies in such a brief quantity of commentary time is kind of uncommon, even with a telescope as highly effective as MeerKAT. Nonetheless, we all know there are extra galaxies ready to be present in upcoming and current MeerKAT observations.
In another latest work, our crew discovered traces of fuel in additional than 80 galaxies (most model new) throughout three separate MeerKAT observations. Every of those observations was initially centered on a single galaxy, just like the “open time” commentary through which we discovered the 49ers.
What’s going to we discover subsequent? We don’t know, however with MeerKAT – and ultimately its extra highly effective successor, the SKA telescope – we’re assured astronomers will flip up lots extra items of gold.