Beautiful, fiery baby stars are born in the frigid, billowing, dark depths of one of the many giant molecular clouds, composed of gas and dust, that haunt the Cosmos. The young star then goes on to evolve through time–first enjoying a flaming youth, a vibrant middle age, and a magnificent old age before it dies. Small stars like our Sun, when they finally approach the end of their stellar existence, first become bloated, swollen, and enormous red giant stars, before they hurl into interstellar space their beautiful shimmering, glimmering outer gaseous layers to become one of the most beautiful objects in the Universe–a planetary nebula. The ghost star that hides itself within the heart of this magnificent, multicolored final blaze of glory, is termed a white dwarf– and it is the dead Sun-like star’s very dense and relatively tiny relic core. In August 2015, a team of astronomers released a breathtaking image of just such a beautiful bubble, dangling like a dazzling, brilliant phantom in the spooky darkness of interstellar space. This new image provides the best view yet of a little-known object dubbed ESO 378-1–and it was captured by the European Southern Observatory’s (ESO’s) Very Large Telescope (VLT) located in northern Chile.
Even though the dazzling, ghostly cosmic apparition appears beguiling, exotic, and mysterious, it is really a familiar type of astronomical object. Nicknamed the Southern Owl Nebula, this glimmering, glowing death shroud of a former star is a planetary nebula with a diameter of about four light years. It acquired its playful and informal nickname from its close visual kin in the northern hemisphere, dubbed the Owl Nebula, which is also catalogued as PN K 1-22 and PN G 283.6+25.3, situated in the constellation Hydra (Female Water Snake).
The Southern Owl Nebula, like other planetaries, has only a very brief existence. Lasting a mere few tens of thousands of years–only the wink of an eye in cosmological time–its “lifespan” is much shorter than a typical stellar lifetime of several billion years.
Planetary Nebulae form as the result of the ejected and expanding gas flowing out from dying, elderly stars. Even though they are intriguing and brilliant objects when they first form, these luminous and varicolored bubbles grow progressively dimmer and finally fade from view as their constituent gas travels away and the central white dwarf grows more and more faint.
The Southern Owl Nebula
The Southern Owl Nebula is about 8,000 years old. It is circular in appearance and displays little in the way of visible internal structure. It was born as the result of the outflow of material from the stellar wind rushing out from a doomed, dying star as it evolved into a white dwarf encircled by planetary nebula of incredible, glimmering beauty. The Southern Owl Nebula is constructed of a trio of concentric shells, with the outermost shell being approximately 20-30% larger than the inner shell. The owl-like appearance of the planetary is the result of an inner shell that is not circularly symmetric. Instead, the inner shell is a barrel-like structure aligned at an angle of 45 degrees to the line of sight.
The planetary contains approximately 0.13 solar-masses of material, composed of a fascinating mix of hydrogen, helium, nitrogen, oxygen, and sulfur–all with a density of less than 100 particles per cubic centimeter. The outer radius is approximately 0.29 parsecs and is expanding with speeds in the range of 27 to 29 kilometers per second into the ambient space between stars.
The 14th magnitude central star has arrived at an important turning point in its evolution whereby it is in the process of condening to create a white dwarf. It possesses 55 to 60% of our Star’s mass, and 41 to 148 times its brightness. It also has a temperature of about 123,000 Kelvin. The dying star has been successfully resolved by NASA’s infrared Spitzer Space Telescope, which reveals a point source that does not show the infrared excess that is normally displayed by a circumstellar disk. 바카라사이트
In the distant future, our Sun will become a white dwarf, surrounded by its very own death shroud of an exquisitely beautiful multicolored planetary nebula. Our Sun is a middle-aged star at about 4.6 billion years of age. It has approximately 5 billion years to go before it begins its death throes. But today our Star is still vibrant, bouncy, and fluffy enough to continue to go on blissfully burning hydrogen in its searing-hot heart as the result of the process of nuclear fusion–which creates heavier atomic elements out of lighter ones–in a process termed stellar nucleosynthesis. When our Sun–and other stars like it–have finally succeeded in fusing their necessary supply of hydrogen fuel in their seething-hot, roiling hearts, their looks start to change. They are now elderly stars, with little time left. In the heart of an elderly Sun-like star, there is a core of helium surrounded by a shell in which hydrogen is still being fused into helium. The shell eventually begins to swell outward, and the extremely hot helium core grows ever larger and larger, as the dying star grows older. The helium core itself finally begins to shrink under its own mighty weight, and it grows increasingly hot. This triggers a new stage of stellar nucleosynthesis. It is now the helium that is being fused to create the heavier atomic element, carbon.