The James Webb Space Telescope continues to provide stunning images of the Universe, proving that the years of development and the delays were well worth the wait! The latest comes from Judy Schmidt (aka. Geckzilla, SpaceGeck), an astrophotographer who processed an image taken by Webb of the barred spiral galaxy NGC 1365. Also known as the Great Barred Spiral Galaxy, NGC 1365 is a double-barred spiral galaxy consisting of a long bar and a smaller barred structure located about 56 million light-years away in the southern constellation of Fornax.
Measuring more than 200,000 light-years in diameter, about twice the size of the Milky Way, NGC 1365 is distinctive for the way its broad arms extend from its central bar to give it a Z-shaped appearance. The galaxy was selected for observations by JWST due to its iconic nature and the amount of its interior structure that is obscured by dust. In particular, its second bar is more prominent in infrared images, and previous instruments (like the Hubble and Spitzer space telescopes) were limited in terms of what they could visualize.
Astronomers theorize that this bar plays a crucial role in the evolution of the galaxy, drawing gas and dust to the core, forming new stars and fueling the supermassive black hole (SMBH), which is about two million solar masses and rotates at a speed close to the speed of light. It is also suspected that this region arose from a combination of dynamical instabilities in the region, possibly due to stellar orbits, density waves, global disk rotation, and the likelihood that the inner bar is faster than the bigger bar.
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The image was acquired by Webb’s Mid-Infrared Instrument (MIRI) and offers new insight into the inner workings of this galaxy. This includes the most detailed look at the central barred region and the many smaller, thinner arms extending from it. The bright center shows the SMBH (the bright dot in the middle) and the halo-shaped star-forming region, and the illuminated dust surrounding it. Bright spots are also dotted across the two largest arms, which look more like extended archipelagos than single structures.
As Schmidt indicates, she processed the image using data provided by the Physics at High Angular resolution in Near Near GalaxieS (PHANGS) team:
“Dusty barred spiral galaxy NGC 1365. Interestingly, the dust bar is not as prominent as it is in visible light. In the center is a modest active galactic nucleus (AGN). Circumnuclear dust is also quite striking. This time I was happy to receive the data reduction from the PHANGS team. It’s much easier because their mosaic was much better matched and aligned.
NGC 1365 and other barred spiral galaxies are of great interest to astronomers with new observations indicating that the Milky Way may also be a barred spiral galaxy. These galaxies are estimated to make up two-thirds of all spiral galaxies in the Universe, and studying them could reveal things about the formation and evolution of ours. Given its advanced suite of infrared optics, the JWST is well suited for studying the nuclei of these galaxies and observing the forces driving things like star formation, supermassive black holes, relativistic jets, and more.
Among his many scientific goals, Webb will study parts of the Universe that are largely inaccessible in visible light astronomy, such as molecular clouds (star-forming regions), circumstellar disks that give rise to planets, and the nuclei of active galaxies. This includes the center of the Milky Way galaxy, which has been very difficult to observe due to all the cosmic dust between it and Earth. These observations will reveal clues about its supermassive black hole (Sagittarius A*), the stars that orbit it, and the dense “galactic bulge” that surrounds it.