If you are fascinated by nature, these pictures of spiral galaxies will not help you escape your magic.
These images show stunning detail in 19 spiral shapes, imaged head-on by the James Webb Space Telescope. The galactic arms are illuminated by a large number of infrared stars, as are the dense galactic cores, where supermassive black holes are located.
The James Webb Space Telescope captured these images as part of the Physics at High Angle Resolution in Nearby Galaxies (PHANGS) programme. Fang It is a long-term program aimed at understanding how gas and star formation interact with galactic structure and evolution.
One of Webb's four primary scientific goals is to study how galaxies form and evolve, and the PHANGS program fuels this effort. VLT, ALMA, Hubble, and now JWST have all contributed to this.
JWST can see in near-infrared (NIR) and mid-infrared (MIR) light. This means that it reveals different details, more detail, than even the powerful Hubble Space Telescope, which operates in visible light, ultraviolet light, and a small portion of infrared light.
In these high-resolution images from the James Webb Space Telescope, the red color is gas and dust emitting infrared light, which the James Webb Space Telescope excels at seeing. Some images contain bright diffraction bumps in the center of the galaxy, which are caused by a huge amount of light.
This could indicate an active supermassive black hole, or it could be from an extremely high concentration of stars.
“This is a clear sign that there may be an active supermassive black hole,” said Eva Scheinerer, a scientist at the Max Planck Institute for Astronomy in Heidelberg, Germany. “Or the star clusters towards the center are so bright that they saturate that area of the image.”
The stars near the galactic center are usually much older than the stars in the arms. The farther a star is from the center of the galaxy, the younger it is. The newest stars appear blue, having blown up the cocoon of gas and dust in which they were born.
Orange masses indicate younger stars. It is still wrapped in a blanket of gas and dust, still actively collecting and shaping materials.
“This is where we can find the newest and most massive stars in galaxies,” said Eric Rozolovsky, a professor of physics at the University of Alberta in Edmonton, Canada.
The new images were released alongside some Hubble views of the same galaxies. These highlight how observing different wavelengths of light reveals or obscures different details in galaxies. In the PHANGS observing program, different telescopes observed galaxies in visible, infrared, ultraviolet, and radio light.
Since the human eye cannot see infrared light, different visible colors are assigned to different wavelengths of light in order to make images meaningful. In the JWST image of NGC 628 above, the galactic center is filled with ancient stars that emit some of the shortest wavelengths of light a telescope can detect. They have been given a blue color to make them visible.
In the Hubble image, the same area appears more yellow and dull. The region emits the longest wavelengths of light that Hubble can sense, so it has different color assignments than the James Webb Space Telescope.
Janice Lee is a project scientist at the Space Telescope Science Institute in Baltimore.
She spoke for us all when she said: “Webb's new images are extraordinary. They are astonishing even to researchers who have studied these same galaxies for decades. The bubbles and filaments are resolved down to the smallest scales ever observed and tell a story about the star formation cycle.”
These galaxies are all spiral galaxies like the Milky Way, which means they are defined by massive arms. The spiral arms resemble waves traveling through space rather than individual stars moving collectively. Astronomers study the arms because they can provide fundamental insights into how galaxies are built and maintained and stop star formation.
“These structures tend to follow the same pattern in certain parts of galaxies,” Rozolovsky added. “We think of them like waves, and their spacing tells us a lot about how the galaxy distributes gas and dust.”
Since it began science operations, the James Webb Space Telescope has provided astronomers with a massive stream of data that will fuel research for years and decades to come. These beautiful images are just part of a larger data release that includes a catalog of about 100,000 star clusters.
“The scale of analysis that can be done with these images is far greater than anything our team can handle,” said Eric Rozolovsky of the University of Alberta. “We are excited to support the community so all researchers can contribute.”