Observer's Corner for August
Death of the Stars!
By Professor Hal Jandorf
As the Summer Triangle (Vega, Deneb and Altair) reaches the zenith on hot August nights, cool deep sky treats await you and your telescope.
There are three examples of Stellar Death: Planetary Nebulae. A planetary nebula is a misnomer and has nothing to do with planetary properties at all.
They are the last death throes of the evolution of normal stars, including our sun. As the core of the star collapses into a small White Dwarf (due to gravity),
the outer atmosphere of the star is slowly ejected from the core as an expanding shell of helium and hydrogen. This forms the faint, round appearance
of the ghostly “planet” in a small telescope (that’s why they are called “Planetary Nebulae”).
M-57 Ring Nebula in Lyra
M-57 Ring Nebula in Lyra. Located nearly centered between Beta and Gamma in Lyra. Best magnification: 100X +
This can be seen as a tiny faint “smoke ring” in small telescopes. Distance is 4100 Light Years. A large telescope is needed to see the center white dwarf.
R.A. 18h 54m Dec. +33 degrees
Our sun will convert hydrogen into helium for approximately 5 billion more years until the core runs out of hydrogen fuel. The sun has a balance between fusion (which tries to expand the sun) and gravity (which forces the sun to contract).
This is called Hydrostatic Equilibrium. When fusion stops, gravity dominates and collapses the star into a White Dwarf. Unused and rarefied hydrogen and helium in the outer atmosphere of the star expands into the Planetary Nebula.
Helix Nebula NGC 7293
Helix Nebula NGC 7293. This is one of the closest P.N. at a distance of 700 Light Years. This faint round glow extends to half the size of the full moon!
In a very dark sky, 7X50 binoculars can detect this object. A nebula filter in the eyepiece at low magnification is best!
R.A. 22h 30m Dec. -20.8 degrees
Planetary nebulae (P.N.) signifies the fluorescent dance of stellar death. Many P.N's are round like the Ring Nebula M-57 in Lyra or the Helix Nebula in Aquarius.
Other P.N's have twisted shells like the Dumbbell Nebula M-27 in Vulpecula. Telescopic views show ghostly, faint blue-green objects like stars that are out of focus.
But astro-imaging shows spectacular colors.
M-27 Dumbbell in Vulpecula
M-27 Dumbbell in Vulpecula. This P.N. is brighter than M-57. It looks like a faint apple core or hourglass, narrowed near the center.
Can be located 3 degrees due north of Gamma in Sagitta. Distance is 1400 Light Years. Best seen at 100X
R.A. 20h 00m Dec. +22.7 degrees
