Astrophoto: Incredible Deep View of Globular Clusters Swarming the Sombrero Galaxy

The Sombrero Galaxy and a Swarm of Globular Clusters. Credit: Rolf Wahl Olsen


You may recall in 2011 we featured an astrophoto by Rolf Wahl Olsen from New Zealand, who took the first amateur image of another solar system, Beta Pictoris. Olsen wrote to tell us he now has a new and better camera and recently focused on a new target with some incredible results.

“This time I have taken a very deep image of the famous Sombrero galaxy (Messier 104) showing 136 globular clusters around it,” Olsen said via email. “I have seen a few images before of the Sombrero with a couple of globular clusters identified, but not to this extent. It is really quite dramatic to be able to see how they literally swarm around the galaxy.”

Highlighted in this image are 136 of the Sombrero’s brightest globular clusters, ranging in magnitudes from 17.5 to 22+, the names and magnitude details of these clusters Olsen has listed on his website. This galaxy may have up to 1,900 in total of these satellite galaxies. Some of these globulars are very large and one is classified as a separate Ultra Compact Dwarf galaxy, SUCD1, the closest known example of such an object.

“I hope you enjoy it,” Olsen said. “This was certainly a fun project, though surprisingly laborious to mark and match all these faint clusters!”

Indeed, this seems to be a nearly Herculean task!

It is not known how the Sombrero amassed such a large number of globular clusters. While the Sombrero (M 104) is a disk galaxy, usually large elliptical galaxies typically have a greater concentration of clusters, such as the approximately 12,000 globular clusters orbiting the giant elliptical galaxy Messier 87. In comparison our own spiral Milky Way galaxy has only around 150-200 such clusters.

The Sombrero lies some 30 million light years away in the direction of the constellation Virgo.

You can find more information on Olsen’s website, and here’s a link to the full resolution image (1MB), which includes the list of details of all 136 globulars, and the unannotated full res image (1MB) is here.

Image details:
Date: 19th April, 22nd and 24th May 2012
Exposure: LRGB: 210:17:17:17m, total 4hrs 21mins
Telescope: 10″ Serrurier Truss Newtonian
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon LRGB E-Series Gen 2
Taken from Olsen’s observatory in Auckland, New Zealand

For more photos, check out Rolf’s astrophoto site.

Spitzer Spots Two Galaxies in One

Infrared imaging of the Sombrero Galaxy (M104) reveals both elliptical and disk structures.


The Sombrero galaxy has a split personalty, according to recent observations by NASA’s Spitzer Space Telescope. Infrared imaging has revealed a hazy elliptical halo of stars enveloping a dual-structured inner disk; before this, the Sombrero galaxy was thought to be only disk-shaped.

Spitzer’s heat-seeking abilities reveal both stars and dust within the Sombrero galaxy, also known as Messier 104 and NGC 4594. The starlight detected at 3.5 and 4.6 microns is represented in blue-green while the dust imaged at 8.0 microns is shown in red.

In addition, Spitzer discerned that the flat disk within the galaxy is made up of two sections — an inner disk composed almost entirely of stars with no dust, and an outer ring containing both dust and stars.

The galaxy’s dual personality couldn’t be so clearly seen in previous visible-light images.

Hubble image of M104. (NASA/The Hubble Heritage Team STScl/AURA)

“The Sombrero is more complex than previously thought,” said Dimitri Gadotti of the European Southern Observatory in Chile and lead author of the report. “The only way to understand all we know about this galaxy is to think of it as two galaxies, one inside the other.”

Although it might seem that the Sombrero is the result of a collision between two separate galaxies, that’s actually not thought to be the case. Such an event would have destroyed the disk structure that’s seen today; instead, it’s thought that the Sombrero accumulated a lot of extra gas billions of years ago when the Universe was populated with large clouds of gas and dust. The extra gas fell into orbit around the galaxy, eventually spinning into a flattened disk and forming new stars.

This is one of the first galaxies to be seen with such a dual structure — even though M104 has been known about since the mid-1700s.

“Spitzer is helping to unravel secrets behind an object that has been imaged thousands of times,” said Sean Carey of NASA’s Spitzer Science Center at CalTech. “It is intriguing Spitzer can read the fossil record of events that occurred billions of years ago within this beautiful and archetypal galaxy.”

At a magnitude of +8, the Sombrero galaxy is just beyond the limit of naked-eye visibility but can be seen with small telescopes (4-inch/100 mm or larger). It is 28 million light-years away and can be found in the night sky located 11.5° west of Spica and 5.5° northeast of Eta Corvi.

Read more on the NASA press release here.