Triple star system burns bright in new image from the James Webb Space Telescope

It’s a scene that could evoke popular fantasy stories, with sparkling stars shining above misty mountaintops, but the James Webb Space Telescope image you see above is of a very real part of our universe. It shows peaks jutting up from a vast nebula that sits about 5,500 light-years away from our planet.

The nebula is NGC 6357, which is also known as the Lobster Nebula in the constellation of Scorpius, the Scorpion. As a vast cloud of mainly molecular hydrogen gas, NGC 6357 is a huge stellar nursery. In the core of the nebula we find the Pismis 24 cluster of hot, young, massive stars, whose ultraviolet light is eating away at the gas from which NGC 6357 is made, ionizing it and clearing out a large cavity inside the nebula.

In the James Webb Space Telescope‘s (JWST) image, taken with its Near-Infrared Camera (NIRCam), we only see a small portion of the nebula, part of the inner edge of its cavity, lined with a mountain range of jagged spikes of molecular gas. These spikes are huge — the largest seen in this image is 5.4 light-years from tip to base, and the tip itself is 0.14 light-years across. Inside that tip you could fit the solar system out to the distance of Neptune, which is about 2.8 billion miles (4.5 billion kilometers) from the sun, 200 times over. The sheer scale of this nebula is mind-boggling.

The extreme size of the nebula goes hand in hand with some of the extreme stars it has given birth to. The brightest stars in the image, sporting the diffraction spikes, are the most massive in the Pismis 24 cluster. One in particular, designated Pismis 24-1, was once thought to be the most massive star known, holding an incredible 300 times the mass of our sun.

However, as it turns out, Pismis 24-1 is not quite that extreme — although it is still impressive. In 2006, the Hubble Space Telescope imaged Pismis 24 and found 24-1 is actually a triple star system. Hubble was able to resolve two of the stars, one of which is 66 times more massive than the sun. The other two stars are what’s known as a spectroscopic binary; they are too close to each other for Hubble or even the JWST to distinguish them, but we can detect their motion about one another by calling on the Doppler shift. It is thought that the two stars in the spectroscopic binary are twins with individual masses about 36 times the mass of our sun.

All three stars are massive enough to end their lives in supernova explosions in about a million years.

The largest spire of molecular gas in the image seems to be pointing toward Pismis 24-1. The gas around it has been eroded by ultraviolet radiation from the stars, but the gas in the spire is denser and can resist the ultraviolet onslaught. Not that it escapes unscathed, though. The gas inside the spire is being stirred up and compressed to the point that it is beginning to undergo gravitational collapse and form more stars. Eventually, those newborn stars will erode the spire from the inside out and they will emerge from their gaseous cocoon to begin new lives in the Milky Way.

Speaking of stars, the scene is littered with thousands of them. Several hundred belong to the Pismis 24 cluster, while many more are in the background, far beyond NGC 6357.

The stars in the image are in false color — remember, the JWST detects infrared light that the human eye cannot see, so it has to be converted into a visible analog. In this image, the color of the stars relates to their stellar type, or how hot and massive they are, and also to how much light-absorbing dust is around them.

The nebula is also presented in false color. Cyan indicates hot, ionized gas that is scattering light from nearby hot stars. Orange shows micron-sized dust particles while red represents cooler, denser molecular hydrogen gas that can still form stars. The denser the molecular gas, the deeper red it has been colored, with the densest gas seen in black because it is opaque and emits no light.

What really completes the scene, however, is the white mist that seems to be evaporating off the jagged mountaintops of gas in the nebula, like a sublimating frost. This isn’t water vapor, but rather gas and dust streaming off the spires as it is energized by the radiation from the stars. This gas then scatters starlight to create a diffuse, wispy and magical quality fitting of a scene straight out of a space fantasy.