NGC 6210, also known as the Turtle Nebula, has fascinated folks since its discovery in 1825. Located 6500 light-years out, in the constellation Hercules, it has recently helped to visually confirm our solar model and the Theory of Stellar Evolution.
According to our models, the life of a Sun-like star ends when the fuel available to its thermonuclear engine runs out after some ten billion years or so. When the star is about to go kaput, it becomes unstable and ejects its outer layers, forming a planetary nebula. This leaves behind a tiny, but very hot, very dense object, known as a white dwarf. Its fate is to slowly cool down and fade away… Stellar evolution theory predicts that our Sun will experience the same fate as NGC 6210 in about five billion years.
Thanks to a super high-res image captured by Hubble, we have visual affirmation of this process in action. This is a star slightly less massive than our Sun at the final stage of its life cycle. The multiple shells of material ejected by the dying star form a superposition of structures with different degrees of symmetry, giving NGC 6210 its odd, turtley shape. This sharp image shows the inner region of this planetary nebula in unprecedented detail, where the central star is surrounded by a pinkish bubble of material that once formed its guts. That is surrounded by a blue bubble of lighter, gaseous material that once formed its outer layers. Then that rests inside the delicate filamentary structures that were once its surface, atmosphere, and anything it vaporized while it swelled to enormous proportions That gives it its trademark appearance. Then, right in the center, you can see a bright white dot. Bammo! That’s the leftover white dwarf!
The closeup picture was created from images taken with Hubble’s Wide Field Planetary Camera 2 through three filters: the broadband filter F555W (yellow) and the narrowband filters F656N (ionized hydrogen), F658N (ionized nitrogen) and F502N (ionized oxygen). The exposure times were 80 s, 140 s, 800 s and 700 s respectively and the field of view is only about 28 arc-seconds across.