THE SOUTHWORTH PLANETARIUM
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Founded January 1970

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THE DAILY ASTRONOMER

Tuesday, May 3, 2016

A May Messiers!


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HAPPY BIRTHDAY, A.A.A.!

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When perusing a star chart, one quite expects to see stars, which most often appear as black dots imprinted on white paper.   A more elaborate chart would also include a grid allowing users to pinpoint a celestial object's precise location. a magnitude key indicating each star's brightness and M-objects.   These are Messier objects and are listed with a capital M followed by a number, such as M13, M31 or M42.    M-objects are named for French astronomer Charless Messier (1730-1817).  Messier was an avid comet hunter who observed many celestial objects that resembled comets when viewed telescopically.  Realizing that other comet hunters might be similarly frustrated when finding these imposters, Messier compiled a catalog of prominent celestial bodies that other astronomers might mistake for comets.

 

This chart features the Messier Objects within the Virgo region.    Each Messier object is denoted with a capital M and a number.  This number indicates the object's position in the Messier Catalog. 

 

Today, we look at a beautiful "May Messier," defined as a Messier object that is visible most of the night in May.    During the next DA school year (Sept 1, 2016 - Aug  4, 2017), we will attempt to examine every single Messier object as a way to commemorate the 200th anniversary of Charles Messier's passing.       For now, we think a single Messier will suffice

 

Look at the bottom of the above star chart and notice the object labeled M104: the Sombrero Galaxy.   Here, deeply imbedded within the depths of Virgo is a distant galaxy notorious for its furiously energetic core.  Its circular disk and bulging center lend it an appearance of Mexican head wear, hence the name.

 

M104: The Sombrero Galaxy.  An unbarred spiral galaxy within the constellation Virgo the Maiden.    Astronomers believe that this distant galaxy might conceal a gigantic black hole in its nucleus.

 

M104 is classified as an "unbarred spiral," meaning that its nucleus is more spherical than bar-shaped.   Our Milky Way is a barred spiral galaxy in which spiral arms radiate away and curl around a central bar.    The Sombrero is as bar less as Prohibition era Kentucky.     Like most galaxies, the Sombrero's nucleus harbors a super massive black hole.  Astronomers estimate its mass to be about one billion times greater than the Sun's.   They can measure this mass by measuring the velocities of surrounding stars.    The faster the stars. the greater the mass of the black hole they're orbiting.

Though its diameter is only about 50,000 light years, compared to the Milky Way's 100,000 light year span, it is a prominent galaxy by virtue of its bulging and brilliant center.    However, as it is more than 16 times dimmer than the faintest naked eye stars, one needs a telescope to see it and a time exposure photograph to discern its more notable features.   

Were we able to see the bodies deeply hidden within Virgo's darkness, we would behold myriad galaxies scattered across the view field.    Virgo is rich in galaxies as it marks the location of the Virgo Cluster of Galaxies.         M104 lurks to the south of this cluster at such a distance that it is difficult to know whether or not it is part of the Virgo Cluster, itself. 

We do know that the Sombrero Galaxy is a gorgeous unbarred spiral that loiters in our mid spring evening sky far beyond our naked eye vantage point in the depths of intergalactic space.