M27 is a glorious orb in the summer night sky, a showpiece that also is a memento mori for what will happen to our own sun and most stars of its type.
The discovery of this remarkable object is credited to Charles Messier, a French astronomer who was a champion comet-finder. He was the first in his country to spot Halley’s Comet on its predicted return of 1758-59. So adapt did he become at discovering comets that King Louis XV dubbed him the “comet ferret.”
Determined not to be thrown off the scent by the many fuzzy, comet-like objects he could see that were not comets, he compiled his Messier list of such things as galaxies, star clusters and nebulas. If he were to search near the star Merak and spy an elongated patch, he could consult his list and exclaim, “Hein? That is not a comet, it’s only M108.” Publication of the list must have been a huge boon for comet hunters of the past but the list is even more valuable to today’s amateur astronomers, as it points out the locations of some of the most beautiful, and easiest to see, deep-space objects.
Two hundred, forty-six years ago this month, Messier was scanning the heavens with a telescope when he stumbled upon a large fuzzy spot in the constellation Vulpecula, the little fox. According to an on-line translation of his notes, he wrote, “On July 12, 1764, I have worked on the research of the nebulae, and I have discovered one in the constellation Vulpecula, between the two forepaws, & very near the star of fifth magnitude, the fourteenth of that constellation. … I have examined it with a Gregorian telescope which magnified 104 times: it appears in an oval shape; it doesn’t contain any star; its diameter is about 4 minutes of arc.”
[M27 floats amid stars in a view I took in Emery county, the early morning of July 13, 2010]
It was the 27th non-comet blob that he had documented, and from then on has carried the designation Messier 27. It also was the first object of its class to be recorded, as M27 is a planetary nebula. It is the closet of all planetary nebulas. NASA pegs it as 1,200 light-years away and 2.5 light-years across.
M27 is called the Dumbbell Nebula because its shape, especially when seen in a smaller telescope, resembles a fitness barbell with two lobes. Through more powerful telescopes the lobes are shown as brighter sections of a round shape.
Of all the objects in Messier’s 110-member list (one is only a double star and a couple of others are considered dubious), only three other planetary nebulas appear: M57, the Ring; M76, called the Barbell, the Little Dumbbell, the Cork and the Butterfly; and M97, the Owl Nebula. Many fainter planetaries have been discovered since his time.
Planetary nebulas are termed that because they often appear like dim planets floating amid the stars; they actually are the remains of normal stars like our own Sun.
NASA’s description from the Astronomy Picture of the Day Site, dated June 26, 2008, says M27 is “now known to be an excellent example of a gaseous emission nebula created as a sun-like star runs out of nuclear fuel in its core. The nebula forms as the star’s outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star’s intense but invisible ultraviolet light.”
At the center of M27, and visible in my photo, is the progenitor star.
When a planetary nebula has puffed off its atmosphere, what is eventually left is termed a white dwarf star — a star that has lost most of its normal matter and is compressed into a tiny bright ball. It could retain half the mass of the sun, smashed into the volume of Earth. Brilliantly bright, a white dwarf can be 200,000 times as dense as the Earth, according to the Goddard Space Flight Center.
The glowing cinder will shine for billions of years before it dies out.
A site operated by Johns Hopkins University for NASA, dedicated to the Far Ultraviolet Spectroscopic Explorer probe, CLICK HERE, does not call the M27 central star a white dwarf. Instead, it says the core star is “on its way to becoming a white dwarf star.” Nevertheless, it’s a most peculiar object, radiating at about 130,000 degrees. Even though it is small, the site adds, “it packs quite a punch in terms of heating the surrounding gas.”