On June 20, 2022, the James Webb Space Telescope spent an hour looking at something called Messier 92 (or M92) which is located far away – it’s 27,000 light-years away! This was part of something called Early Release Science (ERS) program 1334. That’s one of 13 programs that astronomers use to understand how they can get the most out of the telescope.
NASA communicated with four people, Matteo from Italy, Alessandro from California, Roger from New Jersey, and Andy from Raytheon to understand more about what they discovered while trying to observe M92 in space. This was connected to a project that Kristen McQuinn spoke about last November regarding the tiny galaxy WLM.
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Can you tell me about this ERS program? What are its goals?
Alessandro Savino is working on a program that looks at stars located very close to Earth in groups such as M92. These stars can be seen by the James Webb telescope, and help us understand how galaxies and stars work. The things we learn help us figure out far away stars and galaxies too!
We’re working really hard to better understand the telescope. This project is helping us make sure that all measurements are accurate and providing data for other scientist’s projects, too.
Why did you decide to research M92 in particular?
Savino: M92 is an important globular cluster that can help us understand how stars work and evolve. We know a lot about it because it’s close to us, so we use it as a guide when studying stellar systems.
M92 is a very special globular cluster because it is thought to be one of the oldest we have found in our galaxy. Scientists think it is around 12-13 billion years old and contains some very, very old stars that can be seen and studied. This cluster helps us to understand more about what our universe looked like in its ancient days.
The astronomers chose to study the M92 globular cluster because it has a lot of stars that are very close together. (It’s even much denser than the region near our Sun!) This helps them test how their telescope works in areas where stars are super crowded. Studying this type of globular cluster can tell us a lot about how stars evolve over time.
Andy Dolphin said that they can take a really good look at a stars population in M92 because all the stars were formed around the same time with a similar mix of elements, but each one is different in size.
We know that all the stars in the star cluster we are looking at (called ” M92″ ) are roughly the same distance away from us. This is really useful as it means that any differences between them in brightness must be due to how they actually look, not just how far away they are. It makes comparing them easier with models.
Scientists have already studied this cluster of stars using the Hubble Space Telescope and other telescopes. What else can they learn by using Webb?
Webb and Hubble are both powerful telescopes, but they’re different in one important way – Webb operates at longer wavelengths, which is better able to observe stars with very low mass. In fact, we’ve even been able to find stars that are less than 0.1 times the weight of our Sun! That’s close to the boundary where stars become too small and turn into brown dwarfs, which doesn’t have enough gravity for its core to ignite hydrogen.
Correnti said that Webb is a lot faster than Hubble. You need hundreds of hours to see the small and faint stars with Hubble, but it only takes a few hours with Webb.
According to Cohen, these observations weren’t made to push the limits of the telescope. Even so, they still managed to detect such tiny stars without trying super hard.
So what makes these low-mass stars so special?
There are a lot of stars in the universe and scientists want to learn more about them. It has been hard to study stars that have less than half the mass of our sun because it is difficult to understand how they work.
Studying the light coming from stars with low mass can help us figure out how old globular clusters, like M92, are. This helps us learn more about when different parts of the Milky Way were formed. That information has an impact on what we know about our universe’s history.
Why is there a big gap in the middle of the image?
This picture was taken with a camera called Near-Infrared Camera (NIRCam). It has two parts, but there is a “space” in between them. The center of the group of stars was too bright and it would have messed up the data – but it looks pretty similar to pictures already taken by Hubble.
The main purpose of taking this picture was so other scientists could use it for their work. Are you excited about what you’ve done?
We have developed something called the DOLPHOT NIRCam module that helps scientists measure how bright stars and other “star-like” objects are. We created this for the cameras on The Hubble Space Telescope. By using this new module, astronomers can now analyze data from The Hubble and Webb telescopes together to create star catalogs that contain information from both telescopes.
Savino: This is a very important job to help the community. It is taking care of data and making it easier for everyone to understand.
About the Authors:
– Matteo Correnti works at the Space Science Data Center which helps out with exploring space and stars in Rome, Italy.
– Alessandro Savino studies at the University of California, Berkeley in the United States.
– Roger Cohen studies at Rutgers University which is located in New Brunswick, New Jersey also in the United States.
Andy Dolphin is a scientist who works in Tucson, Arizona at Raytheon Technologies. His job is based on research that hasn’t been reviewed by other experts yet.
