James Webb telescope peeks into the birth region of massive stars

(ORDO NEWS) — Massive stars, eight or more times the mass of our Sun, live hard and die young. They often end their short lives in violent explosions called supernovae, but their birth is much more mysterious.

They form in very dense, cold clouds of gas and dust, but little is known about these regions. In 2021, shortly after the launch of the James Webb Space Telescope, scientists plan to study three of these clouds to understand their structure.

“What we’re trying to do is look at the birthplaces of massive stars,” explained Eric Young, principal investigator of the program that Webb will use to study the phenomenon.

He is an astronomer at the Space Research Association of Universities in Columbia, Maryland. “Determining the actual structure of clouds is very important for understanding the process of star formation,” he said.

These cold clouds, which can be up to 100,000 times the mass of the Sun, are so dense that they appear as large dark spots in the sky. While they appear to be devoid of stars, the clouds actually just obscure the light from the background stars.

These dark spots are so thick with dust that they even block infrared rays at some wavelengths, which is invisible to human eyes and can usually penetrate dusty clouds. That is why they are called “infrared dark clouds”. However, Webb’s unprecedented sensitivity makes it possible to observe background stars even through these very dense regions.

Birth Environment and Cookie Dough

To understand how massive stars form, you must understand the environment in which they form. But one of the things that makes studying massive star formation so difficult is that once a star ignites, it emits intense ultraviolet light and strong, strong winds.

“These forces destroy the birth environment in which the star was created,” explained infrared and dark cloud expert Kara Battersby, assistant professor of physics at the University of Connecticut. “The environment you look at after it has formed is completely different from the environment that helped shape it in the first place.

And since we know that dark infrared clouds are places where massive stars can form, but if we look at their structure before stars formed or just started to form, we can understand what kind of environment is needed for the formation of these massive stars. .

Battersby likens the process to baking cookies: once you bake them, they are completely different from the dough.

If you have never seen dough before, you will have no idea how they looked before the baking process. Infrared dark clouds are like raw dough before it is baked. Examining these clouds is akin to being able to look at cookie dough, see what’s in it, and know what its consistency is.

The Importance of Massive Stars

Understanding massive stars and their environment is important for a number of reasons. First, during explosive death, they release many elements that are necessary for life.

Elements heavier than hydrogen and helium, including the building blocks of life on Earth, come from massive stars. Massive stars have turned a universe made up almost entirely of hydrogen into a rich and complex environment capable of producing planets and humans.

Massive stars also produce huge amounts of energy. Once they are born, they give off light, radiation, and winds that can create bubbles in the interstellar medium, possibly causing stars to form in different places. These expanding bubbles could also break up the region where new stars are being formed. Finally, when a massive star dies in a spectacular explosion, it changes its environment forever.

Objectives the study will focus on the following three areas

Brick: One of the most infrared-dark brick-shaped clouds in our galaxy lies near the center of the galaxy, about 26,000 light-years from Earth. A brick over 100,000 times the mass of the Sun doesn’t seem to form any massive stars – yet.

But it has so much mass in such a small area that if it does start forming stars, scientists believe it will be one of the most massive star clusters in our galaxy, very similar to the Arches or Quintuplet cluster, also found near the center. our galaxy.

Serpent: A snake-inspired name, this is an extremely filamentous cloud located about 12,000 light-years away, with a total mass of 100,000 Suns. Scattered along the Serpent are warm, dense dust clouds, each 1,000 times the mass of the Sun, made of gas and dust.

These clouds heat up the young, massive stars that form inside them. The snake may be part of a much longer filament that is the “Bone of the Milky Way”, tracing the spiral structure of the galaxy.

IRDC 18223: About 11,000 light-years away, this cloud is also part of the “Bone of the Milky Way”. It shows active, massive star formation taking place in one part of it, while the other side seems completely calm and unruffled.

The bubble on the active side is already starting to break down the original thread that was there before. While the calm side has not yet begun to form stars, most likely it will happen soon.


To study these clouds, Yang and his team will use background stars as probes. “The more stars you have, the more differences,” Young said. “Each one is like a little pencil ray, and by measuring the color of the star, you can estimate how much dust is in that particular line of sight.”

The scientists will make maps – mostly very deep images – in four different infrared wavelengths. Each wavelength has a different ability to penetrate the cloud.

“If you look at this star and see that it is actually much redder than you would expect, then you can assume that its light has actually passed through the dust, and the dust has made the color redder than a typical, unhidden star. Yang said.

By observing the color difference based on these four different near-infrared measurements and comparing it to a dust darkening and reddening model, Yang and his team are able to measure the dust in that particular line of sight.

The Webb telescope will allow them to do this for the thousands and thousands of stars that penetrate each cloud, providing them with many data points. Since most stars of this type are similar in brightness and color, any noticeable differences that Webb can observe are mainly due to the effect of material between us and the stars.

Only with Webb Telescope

This work can only be done because of Webb’s exquisite sensitivity and superior angular resolution. Webb’s sensitivity allows scientists to see fainter stars and a higher density of background stars. Its angular resolution, the ability to distinguish the smallest details of an object, allows astronomers to distinguish between individual stars.

This study will be conducted under the Webb Guaranteed Time Observations (GTO) program. This program is designed to reward scientists who have helped develop key hardware and software components or technical and interdisciplinary expertise for the observatory. Young was part of the development team that created Webb’s Near Infrared Camera Tool (NIRCam).

The James Webb Space Telescope will be the world’s first space science observatory. Webb will unravel mysteries in our solar system, peer into distant worlds around other stars, and explore the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, the European Space Agency (ESA) and the Canadian Space Agency.


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