constellation Scorpius Archivi

Pismis 24: a glittering glimpse of starbirth

This sparkling scene of star birth was captured by the NASA/ESA/CSA James Webb Space Telescope. What appears to be a craggy, starlit mountaintop kissed by wispy clouds is actually a cosmic dust-scape being eaten away by the blistering winds and radiation of nearby, massive, infant stars.

Called Pismis 24, this young star cluster resides in the core of the nearby Lobster Nebula, approximately 5,500 light-years from Earth in the constellation Scorpius. Home to a vibrant stellar nursery and one of the closest sites of massive star birth, Pismis 24 provides rare insight into large and massive stars. This region is one of the best places to explore the properties of hot young stars and how they evolve.

In what appears as a celestial dreamscape, a blue and black sky filled with brilliant stars covers about two thirds of the image. The stars are different sizes and shades of white, beige, yellow, and light orange. Across the bottom third of the scene is a craggy, mountain-like vista with spire-like peaks and deep, seemingly misty valleys. These so-called mountains appear in varying shades of orange, yellow, and brown. Above their soaring spires is a wispy, ethereal white cloud that stretched horizontally across the scene. Steam appears to rise from the mountaintops and join with this cloud. At the top, right corner of the image, a swath of orange and brown structure cuts diagonally across the sky. — This sparkling scene of star birth was captured by the NASA/ESA/CSA James Webb Space Telescope. What appears to be a craggy, starlit mountaintop kissed by wispy clouds is actually a cosmic dust-scape being eaten away by the blistering winds and radiation of nearby, massive, infant stars.
Called Pismis 24, this young star cluster resides in the core of the nearby Lobster Nebula, approximately 5,500 light-years from Earth in the constellation Scorpius. Home to a vibrant stellar nursery and one of the closest sites of massive star birth, Pismis 24 provides rare insight into large and massive stars. This region is one of the best places to explore the properties of hot young stars and how they evolve. Credit: NASA, ESA, CSA, and STScI, A. Pagan (STScI)

At the heart of this glittering cluster is the brilliant Pismis 24-1. It is at the centre of a clump of stars above the jagged orange peaks, and the tallest spire is pointing directly toward it. Pismis 24-1 appears as a gigantic single star, and it was once thought to be the most massive known stars. Scientists have since learned that it is composed of at least two stars, though they cannot be resolved in this image. At 74 and 66 solar masses, respectively, the two known stars are still among the most massive and luminous stars ever seen.

Captured in infrared light by Webb’s NIRCam (Near-Infrared Camera), this image reveals thousands of jewel-like stars of varying sizes and colors. The largest and most brilliant ones with the six-point diffraction spikes are the most massive stars in the cluster. Hundreds to thousands of smaller members of the cluster appear as white, yellow, and red, depending on their stellar type and the amount of dust enshrouding them. Webb also shows us tens of thousands of stars behind the cluster that are part of the Milky Way galaxy.

Super-hot, infant stars (some almost 8 times the temperature of the Sun) blast out scorching radiation and punishing winds that are sculpting a cavity into the wall of the star-forming nebula. That nebula extends far beyond NIRCam’s field of view. Only small portions of it are visible at the bottom and top right of the image. Streamers of hot, ionized gas flow off the ridges of the nebula, and wispy veils of gas and dust, illuminated by starlight, float around its towering peaks. Dramatic spires jut from the glowing wall of gas, resisting the relentless radiation and winds. They are like fingers pointing toward the hot, young stars that have sculpted them. The fierce forces shaping and compressing these spires cause new stars to form within them. The tallest spire spans about 5.4 light-years from its tip to the bottom of the image. More than 200 of our solar systems out to Neptune’s orbit could fit into the width its tip, which is 0.14 light-years. In this image, the color cyan indicates hot or ionised hydrogen gas being heated up by the massive young stars. Dust molecules similar to smoke here on Earth are represented in orange. Red signifies cooler, denser molecular hydrogen. The darker the red, the denser the gas. Black denotes the densest gas, which is not emitting light. The wispy white features are dust and gas that are scattering starlight.

Webb image of Pismis 24 with compass arrows, scale bar, and color key. Image shows brilliant stars against a blue and black sky covering about two thirds of the image. Across the bottom third is a craggy, mountain-like vista with soaring peaks and deep, seemingly misty valleys. A wispy white cloud stretches horizontally across the mountaintops. At bottom left, compass arrows indicate the orientation of the image on the sky. The north arrow points downward in the 6 o’clock direction. The east arrow points in the 3 o’clock direction. At lower right is a scale bar labeled 1 light-year. The length of the bar is a about one-eighth the total width of the image. Below the image is a color key showing which NIRCam filters were used to create the image and which visible-light color is assigned to each filter. From left to right, filters are: F090W is blue; F187N is blue-green; F200W is yellow-green; F335M is orange; and F470N is red. — This sparkling scene of star birth was captured by the NASA/ESA/CSA James Webb Space Telescope. What appears to be a craggy, starlit mountaintop kissed by wispy clouds is actually a cosmic dust-scape being eaten away by the blistering winds and radiation of nearby, massive, infant stars.
Called Pismis 24, this young star cluster resides in the core of the nearby Lobster Nebula, approximately 5,500 light-years from Earth in the constellation Scorpius. Home to a vibrant stellar nursery and one of the closest sites of massive star birth, Pismis 24 provides rare insight into large and massive stars. This region is one of the best places to explore the properties of hot young stars and how they evolve.
Credit: NASA, ESA, CSA, and STScI, A. Pagan (STScI)

Press release from ESA Webb.

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The protoplanetary disc XUE 1 shows that rocky planets can form in extreme environments; the study has been published in The Astrophysical Journal

An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to provide the first observation of water and other molecules in the inner, rocky-planet-forming regions of a disc in one of the most extreme environments in our Galaxy. These results suggest that the conditions for rocky-planet formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments.

At the centre of the image, a bright light source illuminates a surrounding disc, which transitions from colours of white, grey, to orange. The disc is slightly tilted from upper left to lower right, and has spiral features that are most prominent near the star. Small, rocky objects are scattered throughout the disc. At upper right, there is a gap through which background stars can be seen. — This is an artist’s impression of a young star surrounded by a protoplanetary disc in which planets are forming.
An international team of astronomers have used the NASA/ESA/CSA James Webb Space Telescope to provide the first observation of water and other molecules in the inner, rocky-planet-forming regions of a disc in one of the most extreme environments in our galaxy. These results suggest that the conditions for rocky-planet formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments.
Credit: ESO/L. Calçada

These are the first results from the eXtreme UV Environments (XUE) James Webb Space Telescope programme, that focuses on the characterisation of planet-forming disc in massive-star-forming regions. These regions are likely representative of the environment in which most planetary systems formed. Understanding the impact of environment on planet formation is important for scientists to gain insights into the diversity of the observed exoplanet populations.

The XUE programme targets a total of 15 discs in three areas of the Lobster Nebula (also known as NGC 6357), a large emission nebula roughly 5500 light-years away from Earth in the constellation Scorpius. The Lobster Nebula is one of the youngest and closest massive star formation complexes, and is host to some of the most massive stars in our Galaxy. Massive stars are hotter, and therefore emit more ultraviolet (UV) radiation. This can disperse the gas, making the expected disc lifetime as short as a million years. Thanks to Webb, astronomers can now study the effect of UV radiation on the inner rocky-planet-forming regions of protoplanetary discs around stars like our Sun.

“Webb is the only telescope with the spatial resolution and sensitivity to study planet-forming discs in massive-star-forming regions,” said team lead María Claudia Ramírez-Tannus of the Max Planck Institute for Astronomy in Germany.

Astronomers aim to characterise the physical properties and chemical composition of the rocky-planet-forming regions of discs in the Lobster Nebula using Webb’s Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI). This first result focuses on the protoplanetary disc termed XUE 1, which is located in the star cluster Pismis 24.

Graphic titled “XUE 1 Irradiated Protoplanetary Disc, MIRI Medium -Resolution Spectroscopy” shows a graph of brightness versus wavelength from 4.95 to 5.15 microns, with carbon monoxide peaks highlighted. — This graphic presents some of the first results from the eXtreme UV Environments (XUE) James Webb Space Telescope programme. These results suggest that the conditions for rocky-planet formation, typically found in the discs of low-mass star-forming regions, can also occur in massive-star-forming regions and possibly a broader range of environments.
Astronomers focussed on rocky-planet-forming regions of discs in the Lobster Nebula using Webb’s Medium Resolution Spectrometer (MRS) of the Mid-InfraRed Instrument (MIRI). This first result focuses on the protoplanetary disc termed XUE 1, which is located in the star cluster Pismis 24.
This graphic features the observed signatures of carbon monoxide spanning 4.95 to 5.15 microns
Credit: NASA, ESA, CSA, STScI, J. Olmsted (STScI), M. C Ramírez-Tannus (Max Planck Institute for Astronomy)

“Only the MIRI wavelength range and spectral resolution allow us to probe the molecular inventory and physical conditions of the warm gas and dust where rocky planets form,” said team member Arjan Bik of Stockholm University in Sweden.

Because of its location near several massive stars in NGC6357, scientists expect XUE 1 to have been constantly exposed to a high ultraviolet radiation field throughout its life. However, in this extreme environment the team still detected a range of molecules that are the building blocks of rocky planets.

“We find that the inner disk around XUE 1 is remarkably similar to those in nearby star-forming regions,” said team member Rens Waters of Radboud University in the Netherlands. “We’ve detected water and other molecules like carbon monoxide, carbon dioxide, hydrogen cyanide and acetylene. However, the emission found was weaker than some models predicted. This might imply a small outer disc radius.”

“We were surprised and excited because this is the first time that these molecules have been detected under such extreme conditions,” added Lars Cuijpers of Radboud University. The team also found small, partially crystalline silicate dust at the disc’s surface. This is considered to be the building blocks of rocky planets.

These results are good news for rocky planet formation, as the science team finds that the conditions in the inner disc resemble those found in the well-studied disks located in nearby star-forming regions, where only low-mass stars form. This suggests that rocky planets can form in a much broader range of environments than previously believed.

The team notes that the remaining observations from the XUE programme are crucial to establishing the commonality of these conditions.

“XUE1 shows us that the conditions to form rocky planets are there, so the next step is to check how common that is,” says Ramírez-Tannus. “We will observe other discs in the same region to determine the frequency with which these conditions can be observed.”

These results have been published in The Astrophysical Journal.

Press release from ESA Webb

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