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Challenge #2 – M104, The Sombrero Galaxy

TargetTypeR. A.Dec.ConstellationMagnitudeSize
M104Galaxy12h 41m 03s-11° 44′ 07″Virgo+8.18.4 x 4.9 arcmin

Overview

M104, the Sombrero Galaxy, is part of the Virgo galaxy cluster, which also includes M86 and M84 which we looked at last month.

Virgo is renowned for being rich in galaxies and this month we’re going to track down one of the harder to locate members of that club.

M104 is approximately 8 x 5 arcminutes in size, but we won’t see it that large in smaller backyard scopes. The Sombrero galaxy shines at magnitude 8, which is relatively bright and certainly within reach of most scopes under moderately dark skies.

Sombrero Galaxy, M104, as imaged by the Hubble Space Telescope (source)

This galaxy lies almost edge-on with our line of sight, giving its distinctive shape with a bulge in the center. The galaxy is an ‘unbarred spiral’ around 30 million light-years away from us and 70,000 light-years wide. At its center is believed to be a black hole with the mass of one billion suns!

The Sombrero is distinguished for being the first galaxy to both have a large redshift measured, proving that it was moving away from us at 700 miles per second and so could not be part of our Milky Way. It is also the first galaxy proven to be rotating about that huge central black hole.

There are 2,000 or so globular clusters in the galaxy, around ten times the number in our own Milky Way, and they age M104 at 10-15 billion years old. It’s believed there are well in excess of 100 billion stars in the galaxy.

As usual, let’s begin with finder charts.

Finder Charts

This first chart shows the sky at 10:30pm mid-June.

The Sombrero galaxy is at the center of the image, between the shapes of Virgo and Corvus. At this time it is 30° over the southwest horizon. All of the stars in this SkySafari 6 image are at least magnitude 5 and visible in moderately light-polluted skies.

Click the image for a full-screen version.

The Sombrero Galaxy is 30° over the southwest horizon at 10:30pm in the middle of June.

When you’ve located the right patch of sky, the best way to find it is using the star Algorab (Delta Corvi). A patch of fainter stars looking like an inverse ‘Y’ nearby point the direction. Click on the images for full-screen versions.

Find Algorab and the nearby inverse ‘Y’ group of stars
Inverse monochrome for the same area of sky

The stars in the upside down ‘Y’ are all magnitude 5 and 6, so comfortably in range of all scopes. The last star in the group is 1° away from the Sombrero Galaxy, as shown by the ring in the pictures below.

The final 1° hop from the Inverse ‘Y’. Click for full-screen.

You are now ready to settle in and enjoy observing this delightful galaxy.

Inverse monochrome for the same area of sky

Observation

You will spy this galaxy in a relatively small scope, or even binoculars, looking like a ‘faint fuzzy’ – almost like an unresolvable patch of mist in your eyepiece. Remember to use a low power to begin with to accommodate the size of this object. Take the time to let your eye adjust to what it’s seeing and use averted vision to tease out any detail to shaping that you can.

When you’ve got the shape of it, switch to a higher magnification and see if you can distinguish the brighter center and the brim of the sombrero hat, the line that cuts through the middle.

Larger scopes collect enough light to help distinguish that central bulge from the planar disc. Six inches under a very dark sky or eight under a moderate one should just about do it. Larger scopes still – if you’re lucky enough to enjoy one – will reveal the dust lane cutting through the plane of the galaxy.

This is an awe-inspiring view even in a smaller scope and well worth your effort in hunting it down.