NGC 604 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.
This image from Webb’s NIRCam instrument of star-forming region NGC 604 shows how stellar winds from bright, hot young stars carve out cavities in surrounding gas and dust. Image credit: NASA / ESA / CSA / STScI.
NGC 604 is a star-forming region located 2.73 million light-years away in the Triangulum Galaxy.
Also known as RX J0134.5+3047, it was discovered by the German-born British astronomer William Herschel on September 11, 1784.
NGC 604, which is estimated to be around 3.5 million years old, extends to some 1,300 light-years across.
In the new images from the Near-Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI) onboard the NASA/ESA/CSA James Webb Space Telescope of NGC 604, cavernous bubbles and stretched-out filaments of gas etch a more detailed and complete tapestry of star birth than seen in the past.
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 gives astronomers an opportunity to study these objects at a fascinating time early in their life.
This image from Webb’s MIRI instrument of NGC 604 shows how large clouds of cooler gas and dust glow in mid-infrared wavelengths. Image credit: NASA / ESA / CSA / STScI.
“In Webb’s near-infrared NIRCam image, 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,” the Webb astronomers said.
“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 (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.”
“Webb’s exquisite resolution also provides insights into features that previously appeared unrelated to the main cloud,” they added.
“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 the NASA/ESA 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, there are noticeably fewer stars,” the astronomers said.
“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.”