What JWST found beneath the Sombrero galaxy’s hat

Since its discovery nearly 250 years ago, the Sombrero galaxy has delighted astronomers.

This image of the Sombrero galaxy, also known as Messier 104, represents what an amateur astronomer can capture with a modest, modern setup, revealing a bright, dusty halo of shining stars with a prominent dust lane crossing the center.

It appears nearly edge-on, inclined at a mere 6°.

This wide-field view of the Sombrero galaxy shows a 1.5° region of the sky, with two asterisms (or collections of bright stars) nearby: four stars in a hockey-stick configuration (jaws) just to the right of the galaxy, and the tetrahedron-like “stargate” at the lower-right.

Intrinsically, it’s the brightest known galaxy within 35 million light-years.

The Sombrero galaxy, shown in visible light and imaged by Hubble, is intrinsically the brightest galaxy within some ~35 million light-years of our Milky Way. One must look to the Virgo Cluster, some 50+ million light-years distant, to find significantly brighter, much more massive galaxies.

Puzzlingly, it displays features of both spiral and elliptical galaxies.

This view of the Sombrero galaxy comes from NASA’s Spitzer telescope, showing the inner part of the disk in near-infrared light, while hydrogen glows in red in the mid-infrared in an outer ring. This dual-nature galaxy has its disk-like component better revealed by infrared views.

Prominent dust lanes and spiral arms line a central disk.

This composite view of the Sombrero galaxy combines visible light (Hubble) data with infrared (Spitzer) data to create a view that highlights both the disk component and the elliptical-like halo component of this object.

A giant bulge-like component contains most of its mass, stars, and ~2000 globular clusters.

The Sombrero galaxy appears to have a large number of bright objects embedded in its halo; most of these are globular clusters, commonly found in great abundance around elliptical galaxies but in far smaller numbers around spirals. Whereas the Milky Way has ~150 globulars, the Sombrero has around 2000.

Additionally, its supermassive black hole reaches billions of solar masses.

Although this might not appear to be the Sombrero galaxy, it is: in X-ray light. Hot gas fills the central region of the disk, while bright point sources represent black holes, both within and far behind the galaxy.

All told, it possesses at least twice as many stars as the Milky Way.

This view of the central portion of the Sombrero galaxy showcases the thin, nearly edge-on disk of the galaxy, including many prominent dusty features. Although the spiral-like disk appears majestic, the majority of the galaxy’s mass and light comes from its elliptical halo.

It’s been viewed spectacularly across many wavelengths of light.

This combined view of the Sombrero galaxy uses X-ray data from Chandra, optical data from Hubble, and infrared data from Spitzer. Rich halo and disk features are both revealed across these different wavelength ranges.

The elliptical component can be subtracted out, revealing the spiral-like disk.

By identifying both the spiral (disk-like) and elliptical (halo–like) components of the Sombrero galaxy, one can subtract the elliptical portion of the data out from the optical image, leaving only the disk-like component. This view, created with Hubble data, reveals our best optical views of the disk-like portion alone.

Spitzer’s infrared eyes painted a bulls-eye picture of this galaxy.

But with mid-infrared views from JWST, we see it in a whole new light.

This cross-fade animation switches between JWST (blue) and Hubble (dominantly white) views of the Sombrero galaxy. The JWST view reveals many features never seen before.

The outer dust ring isn’t smooth, but turbulent, cloudy, clumpy, and warped.

Although the Spitzer space telescope’s infrared views could reveal many features, such as the warped disk, within the Sombrero galaxy, the superior size, resolution, and wavelength capabilities of JWST show a large set of features that Spitzer simply couldn’t resolve. The scientific gains, as well as visual ones, are there for us all to reap, with the “blank sky” regions of JWST’s views returning additional science about the presence of “extra” photons that could result from dark matter-driven processes.

Within it, only one solar mass worth of new stars forms annually.

This novel view of the Sombrero galaxy from JWST reveals a central, inner region in more detail than has ever been seen before. The central, supermassive black hole is slightly active, fed predominantly by heated gas in the inner disk that JWST’s mid-infrared instrument is sensitive to.

Centrally, the supermassive black hole slowly feasts on infalling gas.

Compared to the bright, matter-rich ring that lines the outer disk of the Sombrero galaxy, the inner disk is heavily depleted in terms of both stars and gas; the small amount of star-formation within the Sombrero galaxy largely takes place in this dust-rich outer ring.

A sparse, inner disk is largely dust-depleted.

Behind the Sombrero galaxy, which is only ~30 million light-years away, many hundreds of background galaxies can be found. With JWST’s eyes, we’re seeing more of them, and in greater detail, than ever before.

With JWST’s incredible vision, various galaxies abound in the background.

Long ago, the Sombrero galaxy was thought to be a spiral-dominated entity within a rich galactic group. Those other galaxies appear to have been devoured, forming an elliptical halo that still surrounds the disk-like remnant.

The Sombrero likely represents a galactic end-state: where a massive spiral has completely devoured its neighbors.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.