“Give me a man who says this one thing I do, and not those fifty things I dabble in.” –Dwight L. Moody
While star clusters may dabble in a number of physically interesting things, there’s one thing that they do above all others, and that is shine. For today’s Messier Monday, where we spotlight one of the 110 deep-sky wonders of the Messier catalogue, let’s take a look at one of the brilliant open clusters of stars that’s recently formed in our neighborhood of the galaxy and that will appear all winter long: Messier 50.
The fiftieth object in Messier’s catalogue, this star cluster rises just a little bit after the great winter constellation Orion, and can be seen from most locations on Earth over the coming months. Here’s how you can find this object for yourself on a clear night.
As easy as it is to identify Orion after sunset, rising over the eastern horizon, people often forget about two of the night sky’s most spectacular stars that come up just afterwards: Sirius, the brightest star in the entire night sky that dominates the constellation of Canis Major (the big dog), and Procyon, the eighth-brightest star overall and the brightest in Canis Minor (the little dog). If you draw an imaginary line connecting these two brilliant lights, you’re well on your way to finding Messier 50.
About a fifth of the way from Sirius-to-Procyon, you’ll run into an orange giant star — θ Canis Majoris — that’s still clearly visible to the naked eye, even under heavy light pollution. If you can keep onwards in that same direction for another fifth of the way towards Procyon, you’ll arrive at your destination: Messier 50.
While none of the individual stars in M50 are visible to the naked eye, the entire cluster as a whole can be seen with averted vision under very dark skies, and may have been found as early as 1711 by Cassini (the person, not the spacecraft)! Messier himself (re?)discovered this object in 1772, declaring it to be a:
Cluster of small stars, more or less brilliant, above the right loins of the Unicorn, above the star Theta of the ear of Canis Major, & near a star of 7th magnitude. It was while observing the Comet of 1772 that M. Messier observed this cluster. He has reported it on the chart of that comet, on which its trace has been drawn.
Here’s what it looks like in modern equipment comparable to Messier’s.
It’s easy to see how a cluster like this could evade detection for so long, even if it’s technically visible to the naked eye. After all, it’s silhouetted against a dense backdrop of stars with approximately equal brightness: that’s the plane of our galaxy, where most star clusters are found!
But through even modestly improved equipment, you can see a whole lot more.
What appeared to be a loose collection of dim stars actually turns out to be a huge number of bright, young blue stars packed together into a very small region on the sky, highlighted by the occasional red giant star.
In reality, this cluster is somewhere around 3,200 light-years away, placing it among the more distant of the open clusters in Messier’s catalogue. For something so far away to still be visible to the naked eye, you might think that means something interesting about this object. Well, you’d be right!
This is a very young star cluster, with an estimated age of just 78 million years, making it even younger than the Pleiades. Young clusters mean they’re filled with the youngest, hottest and bluest stars, which are also the ones that shine most brightly, explaining why a mere collection of stars that’s so distant can be seen by even the naked eye!
And even though the cluster itself takes up about a third-of-a-degree on the sky, it’s really the inner center of the cluster — spanning a mere 10 light-years in diameter — that shines the brightest.
Literally hundreds of individual stars become visible with long-exposure techniques, revealing not only bright blue stars and red giants, but also dimmer, yellower-and-redder stars that ought to far outnumber their brighter counterparts. It wouldn’t be a stretch to imagine nearly a thousand stars total in this cluster!
For a different view, we can always look to the infrared, and see what wonders show up in a new wavelength. Typically, redder stars will shine more brightly, while bright blue stars will appear less influential, and oftentimes “hidden” red stars will show themselves!
The red giants pop out very clearly, but the sheer number of faint, dim stars that show themselves in the infrared are what really stand out for me.
I love showing you what goes on inside the more hi-resolution photos, so enjoy this dive inside the NOAO photo with me, the most “professional” astrophoto I could find of this object; you won’t wonder about my estimate of 1000 stars after you look at this!
But there is one more thing you might be legitimately wondering: if this star cluster is so young, is there any dust left? The youngest clusters — typically of under 100 million years — oftentimes have surrounding dust that light can reflect off of, ionize, or otherwise interact with.
Well, none of the images so far have really said very much one way or the other, but I’ve saved the most visually stunning one for last, courtesy of the Canada-France-Hawaii telescope!
The answer, sadly, is no; there is no more nascent gas from the molecular cloud that gave birth to this star cluster. Instead, the cluster is dominated by the short-lived, bright blue stars that rush towards their red giant phase and an early grave, which will leave behind the longer-lived, sun-like stars that will eventually disperse throughout the galaxy, perhaps even giving rise to life and future civilizations like ours!
Every star cluster — every stellar nursery — is another chance the Universe gives us at a world like us, and I think of this every time I look at a star cluster in the night sky! That wraps up another Messier Monday, and including today, we’ve looked at the following objects:
- M1, The Crab Nebula: October 22, 2012
- M2, Messier’s First Globular Cluster: June 17, 2013
- M5, A Hyper-Smooth Globular Cluster: May 20, 2013
- M7, The Most Southerly Messier Object: July 8, 2013
- M8, The Lagoon Nebula: November 5, 2012
- M11, The Wild Duck Cluster: September 9, 2013
- M12, The Top-Heavy Gumball Globular: August 26, 2013
- M13, The Great Globular Cluster in Hercules: December 31, 2012
- M15, An Ancient Globular Cluster: November 12, 2012
- M18, A Well-Hidden, Young Star Cluster: August 5, 2013
- M20, The Youngest Star-Forming Region, The Trifid Nebula: May 6, 2013
- M21, A Baby Open Cluster in the Galactic Plane: June 24, 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
- M31, Andromeda, the Object that Opened Up the Universe: September 2, 2013
- M32, The Smallest Messier Galaxy: November 4, 2013
- M33, The Triangulum Galaxy: February 25, 2013
- M34, A Bright, Close Delight of the Winter Skies: October 14, 2013
- M36, A High-Flying Cluster in the Winter Skies: November 18, 2013
- M37, A Rich Open Star Cluster: December 3, 2012
- M38, A Real-Life Pi-in-the-Sky Cluster: April 29, 2013
- M39, The Closest Messier Original: November 11, 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
- M50, Brilliant Stars for a Winter’s Night: December 2, 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
- M56, The Methuselah of Messier Objects: August 12, 2013
- M57, The Ring Nebula: July 1, 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
- M71, A Very Unusual Globular Cluster: July 15, 2013
- M72, A Diffuse, Distant Globular at the End-of-the-Marathon: March 18, 2013
- M73, A Four-Star Controversy Resolved: October 21, 2013
- M74, The Phantom Galaxy at the Beginning-of-the-Marathon: March 11, 2013
- M75, The Most Concentrated Messier Globular: September 23, 2013
- M77, A Secretly Active Spiral Galaxy: October 7, 2013
- M78, A Reflection Nebula: December 10, 2012
- M79, A Cluster Beyond Our Galaxy: November 25, 2013
- 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
- M94, A double-ringed mystery galaxy, August 19, 2013
- M97, The Owl Nebula, January 28, 2013
- M99, The Great Pinwheel of Virgo, July 29, 2013
- M101, The Pinwheel Galaxy, October 28, 2013
- M102, A Great Galactic Controversy: December 17, 2012
- M103, The Last ‘Original’ Object: September 16, 2013
- M104, The Sombrero Galaxy: May 27, 2013
- M108, A Galactic Sliver in the Big Dipper: July 22, 2013
- M109, The Farthest Messier Spiral: September 30, 2013
Come back next week, where another deep-sky wonder of the night awaits you, only here, only on Messier Monday!