“It’s coming right for us!” –Uncle Jimbo, from South Park
Welcome back to another Messier Monday, only here on Starts With A Bang! Each Monday, we take an in-depth look at one of the 110 deep-sky objects that make up the Messier Catalogue, the first accurate and comprehensive deep-sky catalogue of relatively bright, extended celestial objects that can be viewed with even the most primitive of skywatching equipment under good skies. Each one of these objects — ranging from nebulae to star clusters to galaxies — holds its own, unique story.
This week, we’re going to travel deep into the Virgo Cluster — the nearest giant cluster of galaxies to us — to find one of the most extreme objects in the entire night sky. We’ve entered the Virgo Cluster once before here on Messier Monday, but we’ll be going back often; there are a whopping fifteen galaxies in the Virgo Cluster represented in the Messier Catalogue! Today, we’re taking a look at a unique, very large elliptical galaxy, Messier 86. Here’s how to find it.
The brightest star in the northern celestial hemisphere is the orange giant Arcturus, which you can always easily find by following the “arc” of the Big Dipper‘s handle. A little farther along — if you “speed-on” — you can find the bright blue star, Spica, with the planet Saturn hanging out nearby towards the east these days. But if you look in the other direction, towards the west of the imaginary line connecting Arcturus-to-Spica, you’ll see a few other prominent stars, including Vindematrix and Denebola. If you can locate those stars, you can find Messier 86.
Practically directly between those two stars, there are virtually no other stars that stand out; the closest you’ll get are the fifth-magnitude ones labelled above. But directly between those two stars — practically equidistant from both — you’ll find a series of fuzzy, dim lights through a telescope or binoculars. Look for the following configuration of Hipparcos stars through your eyepiece(s), and you’ll be well on your way to finding Messier 86.
Let’s remind ourselves what the Virgo Cluster is, to get a sense of what we’re looking into when we’re seeing this object. A collection of more than 1,000 large galaxies, the Virgo Cluster literally dwarfs all the other, smaller clusters and groups within 50 million light-years of our Milky Way.
Deep in the heart of the Virgo Cluster — which is where we’re looking — there are a series of big, intrinsically bright, very massive galaxies. Some of the brightest — and their relative positions — are shown below.
This galaxy, M86, is actually part of a very famous chain of galaxies, Markarian’s Chain, found there. Messier 86 is the giant elliptical that’s second-from-the-end, as pointed out with the orange arrow below.
Giant elliptical galaxies are rarities in our local corner of the Universe; we are dominated by spirals, both large and small. What’s so different about the Virgo Cluster? When you get this much mass together in such a (relatively) small region of space, gravitational interactions and mergers between galaxies is much more common.
And when approximately equal-sized objects merge together, or when many mergers take place over billions of years, the result is inevitably larger, more elliptically-shaped galaxies.
We find that in relatively sparse regions — like our local group — practically all of the galaxies are spirals, while in large clusters and superclusters — like Virgo — a great percentage are ellipticals. The percentage of ellipticals will only rise as time goes on.
So what’s so special about Messier 86?
At around 53 million light-years distant, it lies in the heart of the Virgo cluster, just slightly off-center from the cluster’s calculated center-of-mass. With more than three thousand globular clusters in its halo — maybe 20 times the number our Milky Way has — it’s full of a huge number of stars that are much older than the typical stars found within our galaxy.
As a giant elliptical, it looks rather non-descript; far less interesting, visually, than its neighboring, merging pair of galaxies known best as The Eyes. It appears to be having dust stripped away from it, and may be merging with the smaller galaxy seen directly atop it in the image above.
But there’s something fantastic that separates Messier 86 from all of its nearby neighbors.
You see, being some 50 million light-years away in an expanding Universe, the entire Virgo Cluster recedes from us at an average of about 1,000 km/sec, or some significant fraction (0.3%) the speed of light! But while all the other galaxies in the image above recede from us at somewhere around that speed, Messier 86 approaches us at some speed between 244 and 419 km/sec, depending on who’s measuring it!
How is this possible? Remember that every galaxy in the Universe, while they’re all caught up in the Hubble expansion of the Universe, they also are subjected to the local gravitational field of wherever they’re located. In the case of Messier 86, it’s on the opposite side of the Virgo Cluster from us, and is speeding towards the center of it so quickly — possibly as great as 1,500 km/sec — that it’s actually blueshifted relative to our point of view!
You might be skeptical of this claim, but you wouldn’t be if you looked at the Chandra X-ray image, which clearly shows a “tail” to this galaxy as it plows through the intra-cluster medium at breakneck speed!
This is actually fairly typical of galaxies in the Virgo Cluster, to have what we call peculiar velocities of as much as a few thousand km/sec. Messier 86 isn’t even the fastest blueshift in the Virgo Cluster; that distinction belongs (currently) to IC 3258, which approaches us at more than 500 km/sec. But it is the most blueshifted of not only all Messier galaxies, but of all Messier objects, period!
Pretty remarkable, especially for such an un-remarkable-looking elliptical galaxy.
So don’t just look up at this object as a “common,” boring elliptical dead-and-red galaxy; this is one of the most vibrant, speeding galaxies — relative to its home cluster’s center-of-mass, especially — that you can find in the entire sky! Explore the Virgo Cluster if you get a chance; it’s high in the night sky for the early part of the night now and for the next few months; don’t miss it!
- M1, The Crab Nebula: October 22, 2012
- M5, A Hyper-Smooth Globular Cluster: May 20, 2013
- M8, The Lagoon Nebula: November 5, 2012
- M13, The Great Globular Cluster in Hercules: December 31, 2012
- M15, An Ancient Globular Cluster: November 12, 2012
- M20, The Youngest Star-Forming Region, The Trifid Nebula: May 6, 2013
- M25, A Dusty Open Cluster for Everyone: April 8, 2013
- M29, A Young Open Cluster in the Summer Triangle: June 3, 2013
- M30, A Straggling Globular Cluster: November 26, 2012
- M33, The Triangulum Galaxy: February 25, 2013
- M37, A Rich Open Star Cluster: December 3, 2012
- M38, A Real-Life Pi-in-the-Sky Cluster: April 29, 2013
- M40, Messier’s Greatest Mistake: April 1, 2013
- M41, The Dog Star’s Secret Neighbor: January 7, 2013
- M44, The Beehive Cluster / Praesepe: December 24, 2012
- M45, The Pleiades: October 29, 2012
- M48, A Lost-and-Found Star Cluster: February 11, 2013
- M51, The Whirlpool Galaxy: April 15th, 2013
- M52, A Star Cluster on the Bubble: March 4, 2013
- M53, The Most Northern Galactic Globular: February 18, 2013
- M60, The Gateway Galaxy to Virgo: February 4, 2013
- M65, The First Messier Supernova of 2013: March 25, 2013
- M67, Messier’s Oldest Open Cluster: January 14, 2013
- M72, A Diffuse, Distant Globular at the End-of-the-Marathon: March 18, 2013
- M74, The Phantom Galaxy at the Beginning-of-the-Marathon: March 11, 2013
- M78, A Reflection Nebula: December 10, 2012
- M81, Bode’s Galaxy: November 19, 2012
- M82, The Cigar Galaxy: May 13, 2013
- M83, The Southern Pinwheel Galaxy, January 21, 2013
- M86, The Most Blueshifted Messier Object, June 10, 2013
- M92, The Second Greatest Globular in Hercules, April 22, 2013
- M97, The Owl Nebula, January 28, 2013
- M102, A Great Galactic Controversy: December 17, 2012
- M104, The Sombrero Galaxy: May 27, 2013
Come back next week, where we’ll look at another one of the deep-sky objects that make up the Messier Catalogue, only here, only on Messier Monday!