Decoding Star Genesis: Webb’s Infrared Insight Into NGC 604

NGC 604 (Webb NIRCam Image)

This image from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) of the star-forming region NGC 604 shows how stellar winds from bright, hot young stars carve out cavities in surrounding gas and dust. Credit: NASA, ESA, CSA, STScI

Unique Opportunity To Study High Concentration of Massive, Young Stars Nearby

In the astronomy field, the term “nearby” is quite relative. Neighboring galaxies to our home galaxy, the Milky Way, are a few million light-years away. In contrast, some of the most distant galaxies ever detected, closer to the Big Bang, are billions of light-years away. In some cases, the ability to study nearby objects at an extremely high resolution can help astronomers better understand more distant objects.

Take the star-forming region NGC 604 as one example. Located 2.73 million light-years away in the nearby Triangulum galaxy, this region is similar to familiar starbirth regions in our Milky Way galaxy, such as the Orion Nebula, but it is much larger in extent and contains many more recently formed stars. Such regions are small-scale versions of more distant “starburst” galaxies, which underwent an extremely high rate of star formation.

NGC 604 (Webb MIRI Image)

This image from NASA’s James Webb Space Telescope’s MIRI (Mid-Infrared Instrument) of star-forming region NGC 604 shows how large clouds of cooler gas and dust glow in mid-infrared wavelengths. This region is a hotbed of star formation and home to more than 200 of the hottest, most massive kinds of stars, all in the early stages of their lives. Credit: NASA, ESA, CSA, STScI

Peering Into the Tendrils of NGC 604 With NASA’s Webb Space Telescope

The formation of stars and the chaotic environments they inhabit is one of the most well-studied, but also mystery-shrouded, areas of cosmic investigation. The intricacies of these processes are now being unveiled like never before by NASA’s James Webb Space Telescope.

Two new images from Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) showcase star-forming region NGC 604, located in the Triangulum galaxy (M33), 2.73 million light-years away from Earth. In these images, cavernous bubbles and stretched-out filaments of gas etch a more detailed and complete tapestry of star birth than seen in the past.

Insights Into NGC 604

Sheltered among NGC 604’s dusty envelopes of gas are more than 200 of the hottest, most massive kinds of stars, all in the early stages of their lives. These types of stars are B-types and O-types, the latter of which can be more than 100 times the mass of our own Sun. It’s quite rare to find this concentration of them in the nearby universe. In fact, there’s no similar region within our own Milky Way galaxy.

This concentration of massive stars, combined with its relatively close distance, means NGC 604 provides astronomers with an opportunity to study these objects at a fascinating time early in their life.

This video compares images of star-forming region NGC 604 taken in visible light with the Hubble Space Telescope’s WFPC2 (Wide Field and Planetary Camera 2), near-infrared with the James Webb Space Telescope’s NIRCam (Near-Infrared Camera), and mid-infrared with Webb’s MIRI (Mid-Infrared Instrument). Credit: NASA, ESA, CSA, Alyssa Pagan (STScI)

Webb’s Near-Infrared and Mid-Infrared Observations

In Webb’s near-infrared NIRCam image (image at top of page), the most noticeable features are tendrils and clumps of emission that appear bright red, extending out from areas that look like clearings, or large bubbles in the nebula. Stellar winds from the brightest and hottest young stars have carved out these cavities, while ultraviolet radiation ionizes the surrounding gas. This ionized hydrogen appears as a white and blue ghostly glow.

The bright orange-colored streaks in the Webb near-infrared image signify the presence of carbon-based molecules known as polycyclic aromatic hydrocarbons, or PAHs. This material plays an important role in the interstellar medium and the formation of stars and planets, but its origin is a mystery. As you travel farther from the immediate clearings of dust, the deeper red signifies molecular hydrogen. This cooler gas is a prime environment for star formation.

NGC 604 (Webb NIRCam Compass Image)

This image of the NGC 604, captured by Webb’s NIRCam (Near-Infrared Camera) shows compass arrows, scale bar, and color key for reference.
The north and east compass arrows show the orientation of the image on the sky.
The scale bar is labeled in light-years, which is the distance that light travels in one Earth-year. (It takes 3 years for light to travel a distance equal to the length of the scale bar). One light-year is equal to about 5.88 trillion miles or 9.46 trillion kilometers.
This image shows invisible near-infrared wavelengths of light that have been translated into visible-light colors. The color key shows which NIRCam filters were used when collecting the light. The color of each filter name is the visible light color used to represent the infrared light that passes through that filter.

Webb’s exquisite resolution also provides insights into features that previously appeared unrelated to the main cloud. For example, in Webb’s image, there are two bright, young stars carving out holes in dust above the central nebula, connected through diffuse red gas. In visible-light imaging from NASA’s Hubble Space Telescope, these appeared as separate splotches.

Webb’s view in mid-infrared wavelengths also illustrates a new perspective into the diverse and dynamic activity of this region. In the MIRI view of NGC 604 (2nd image from top of page), there are noticeably fewer stars. This is because hot stars emit much less light at these wavelengths, while the larger clouds of cooler gas and dust glow. Some of the stars seen in this image, belonging to the surrounding galaxy, are red supergiants – stars that are cool but very large, hundreds of times the diameter of our Sun. Additionally, some of the background galaxies that appeared in the NIRCam image also fade. In the MIRI image, the blue tendrils of material signify the presence of PAHs.

NGC 604 is estimated to be around 3.5 million years old. The cloud of glowing gases extends to some 1,300 light-years across.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

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