M 27 - HISTORICAL

1 - THE M27 DISCOVER

The Dumbbell nebula was discovered on the 12th July 1764 by the French astronomer Charles Messier. At the time of this discovering, he described it as a nebula without stars, perhaps because of the weak magnitude of the star in the middle of the nebula :

"Nebula without star, discovered in Vulpecula, between the two forepaws, & very near the star 14 of that constellation, of 5th magnitude according to Flamsteed; one can see it well with an ordinary telescope of 3.5-foot ; it appears of oval shape, & it contains no star. M. Messier has reported its position on the chart of the Comet of 1779, which was engraved for the volume of the Academy of the same year. Observed again January 31, 1781."

This nebula is the 27th object of Celeste that Charles Messier put in his classification, from which the name M27. In the XVIIIth century, an other astronomer, William Herschel, described it as "a double nebula tied by a gaze cloud ", considering the resemblance of the nebula with the number 8.So that's because the nebula's name is "Dumb-bell". William Herschel called, for the first time, nebulas like M27 "planetary nebula" because of their circularly form. The Dumbbell Nebula is in fact the first nebula which has ever been observed.

2 - THE PAST AND THE FUTURE OF M27

a) The past of M27

The Dumbbell nebula is the rest of a supernova aged 3 500 years old. It's the result of an explosion of a massive star. At the end of its life, this star became a "blue dwarf" after ejecting in space, the differents gas layers that compose the nebula. The gas layer due to this supernovae has spread since its explosion and got a form under which we can observe it nowadays. The Dumbbell nebula is always in continuous extension. Its center star is always visible nowadays but its low magnitude (13.5) prevent from observing at naked eye.

b) Future of M27

Like all nebula, M27 has it own speed of expension. In effect, the gas envelopes which compose its, deviate from its centre little by little, with the speed of 6,8 arcsecond per centery. This envelope will continue to deviate in the space at this speed. By way of the grant surface area on this the gas will be expanse, the nebula will become less and less visible with the time, but it will be more expansive in the space. The blue dwarf in centre will coll with the time. Finally, like the gas envelopes, it will disappear out of our sight.