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Messier Monday: An Elliptical Rotating Wrongly, M59

There’s no wrong way to be a galaxy, but this one sure does challenge our expectations.

“Fantasy is a necessary ingredient in living, it’s a way of looking at life through the wrong end of a telescope. Which is what I do, and that enables you to laugh at life’s realities.” –Dr. Seuss

On the night of a new Moon, there’s no better time to go hunting for galaxies at any location with dark skies. Of all the 110 Messier objects — deep-sky fixtures from our galaxy and beyond — a full 40 of them are galaxies. In general, galaxies can be spirals or ellipticals, but these can be further classified into dwarfs, lenticulars and barred spirals.

Image credit: Mike Keith’s Periodic Table of Messier Objects, via http://cadaeic.net/astro/PeriodicMessier.htm.

Only six of the Messier objects are true giant ellipticals, and today’s object, Messier 59, is perhaps the most unusual of them all. Not because of its location, mind you; it’s located deep within the Virgo cluster, where all of Messier’s ellipticals except last week’s entry can be found. Here’s how to locate it for yourself.

Image credit: me, using the free software Stellarium, available at http://stellarium.org/.

Clearly visible from the northern hemisphere, the Big Dipper is perhaps the most recognizable sight in the night sky, with the prominent constellation of Leo shining brightly beneath the dipper’s cup. If you draw an imaginary line from Leo’s brightest star through it’s second brightest — from Regulus to Denebola — you’ll come to Vindemiatrix, the brightest star for about 10° in any direction.

Image credit: me, using the free software Stellarium, available at http://stellarium.org/.

Look in between Vindemiatrix and Denebola if you will: you’ll see four stars (labelled above) in a “kite” formation. Many galaxies of the Virgo Cluster — the nearest cluster of 1000+ galaxies to us — can be found in there, including today’s object, Messier 59. To get there, locate the bottom star of the kite: ρ Virginis, easily visible from most suburban (and darker) skies with the naked eye.

If you can drop a perpendicular line from ρ Virginis to the imaginary line that connects Vindemiatrix to Denebola, Messier 59 will be the faint, fuzzy isolated sight that awaits you at that intersection.

Image credit: me, using the free software Stellarium, available at http://stellarium.org/.

Through even a modest, small telescope, it’s visible as a bright central core that gradually dims out as you move away from the center, located very close to another of Messier’s ellipticals: M60. It was first observed by Messier just four days after its discovery — by Johann Koehler — on April 15th, 1779. His description was as follows:

Nebula in Virgo & in the neighborhood of the preceding, on the parallel of epsilon [Virginis], which has served for its determination: it is of the same light as the above, equally faint.

To Messier’s instruments, it might have looked something like this.

Image credit: © 2007 — George Sauter, via http://home.comcast.net/~rc_flier/dso.html.

Indistinct, faint and nebulous above all else, this is, in fact, one of the most massive objects in the entire Virgo Cluster, coming in only behind M49, M60 and the giant M87. But unlike the other giant ellipticals, Messier 59 is much longer in one direction than the other: it’s very non-spherical and truly ellipsoidal!

Image credit: National Optical Astronomy Observatory/Association of Universities for Research in Astronomy/National Science Foundation, via http://tcaa.us/Astronomy/Messier/Messier.aspx?id=M59.

Like many giant ellipticals, it’s found in a dense cluster of many galaxies and is likely the result of many major mergers. It contains little neutral gas or dust, has thousands of globular clusters (compared to just 150-200 or so for the Milky Way), and — as a look in the infrared reveals — has practically no new regions of star formation or hot, blue stars!

Image credit: Wide-field Infrared Survey Explorer (WISE), via http://www.jpl.nasa.gov/spaceimages/search_grid.php?sort=mission&instrument=WISE+Telescope. Messier 59 is at left; the green “tracks” are asteroids in our Solar System!

What it also has in common with many giant ellipticals is a huge black hole at its center. There’s obviously something interesting happening at the core, because it’s extremely bright in the infrared and the visible, and yet has no hot, young stars in there.

But things really get interesting if we start examining the motions of stars in this innermost region of M59.

Image credit: McDonald Observatory, NASA/AURA/STScI, via http://mcdonaldobservatory.org/news/gallery/core-galaxy-ngc-4621.

Can you see a disk-like feature in there? (Maybe if you squint?) This inner region has stars that are rotating in the opposite direction from the rest of the galaxy, a super bizarre phenomenon.

What could be causing it? Have a look at the X-ray (from Chandra, on the left) next to the visible light image (from SDSS, on the right) below.

Images credit: NASA / Chandra (Left); Sloan Digital Sky Survey (Right).

The innermost 200 light-years or so must be counterrotating, the smallest region in a galaxy ever observed to do so! Incredibly, the mass of the black hole required to cause these X-ray and gravitational effects must be a whopping 270 million Solar masses, nearly 100 times as massive as the Milky Way’s black hole.

There are also central outflows coming off of this galaxy, and this was one of the key galaxies in discovering the connection between central black holes and how giant galaxies form-and-evolve!

Image credit: courtesy of Sloan Digital Sky Survey/WIKISKY, via http://www2011.mpe.mpg.de/highlights.html.

The Sloan Digital Sky Survey has my favorite wide-field image of this galaxy,

Image credit: Sloan Digital Sky Survey, via Courtney Seligman at http://cseligman.com/text/atlas/ngc46.htm.

while the Hubble Space Telescope provides an outstanding view of just how much brighter this galaxy’s core region is than the rest of the galaxy itself.

Image credit: NASA / STScI / Hubble Legacy Archive, some image cleanup by me.

Of all the galaxies in Virgo, Messier 59 is home to the very first supernova ever detected as it went off in one: all the way back in 1939. (M87’s supernova in 1919 wasn’t detected until three years after-the-fact!) Amazingly, since that 1939 event, that galaxy has gone 85 years without another one!

And with that remarkable fact, we come to the end of another Messier Monday. Including today’s object, we’ve examined:

Thanks for joining me today, and enjoy your dark, new-Moon skies tonight!

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