Image Credit & Copyright: European Southern Observatory (ESO).
There’s a ghost near the heart of the galaxy. This planetary nebula cataloged as IC 1295 resides a in the constellation Scutum (The Shield) roughly 3300 light years away. Though there have been many renditions of this object produced, this is the most detailed ever.
This faint, dying star goes almost unnoticed near the massive star field that is the core of our galaxy. Hidden in the bright lights of the star city, near downtown, everyone else is too busy to notice this green, transparent ghost among us. It’s worth mentioning in the event that you’re asking; that other planetary nebula, (dying stars) have multiple colors or at least, there aren’t many solid green ones. The reason for this is that each chemical element glows in its own color and this particular object is comprised of primarily ionized oxygen. Near the center of this object you can see the near death star, faint and blue, now in its white dwarf phase. With the outer shells of itself dispersed into space, the now exposed inner layers shower its outer layers with massive amounts of UV radiation which ionizes the material, rendering it aglow.
Want a little more detail into what a planetary nebula is?
Inside the core of a star, pressures and temperatures are so great that a process called Thermo Nuclear Fusion can take place. It’s important to remember that stars don’t “burn” as burning is a chemical reaction. Thermo Nuclear Fusion is a nuclear reaction. Hydrogen atoms are being fused together to create helium atoms. When the two nuclei fuse together the combined mass is slightly less than the sum of the original nuclei and the difference is released as energy. As the progenitor star burns through all of its available fuel the star quickly begins to die. The key word here is “available” fuel as most of the hydrogen in a star will never be fused in the core. When this happens gravity begins to win over the outward pressure of the nuclear reaction. The star then begins to crush down onto itself from the extreme inward pressure that gravity is now imposing on it.
Ironically enough, this very process of compression causes the core to become super-heated. Core temperatures rise to ten-times the temperature they were while in the main sequence phase. Once the temperature reaches 180,000,000 degrees the temperature will be hot enough to fuse helium into carbon. As this continues, the star will begin to quickly use up its available helium fuel. The massive temperatures cause the star to swell and the asymptotic giant branch aka, the infamous red giant phase begins. Vast layers or shells of gas are then released into the surrounding cosmos creating what’s known as proto-planetary or pre-planetary nebula (PPN’s). The furiously hot star whose inner layers are now exposed, radiate massive amounts of ultraviolet radiation rendering the surrounding material aglow and that’s where the planetary nebula (PN) phase begins.
When the available helium begins to run dry, gravity once again begins to take over, and again the star is crushed in upon itself; this time down to about the size of the Earth. It is at this point when electron degeneracy pressure is enabled. This means that electrons themselves are being crushed together so tightly that their repulsive pressure on one another will hold the star up against the inward crush of gravity. That is where it will remain for billions of years as a white dwarf.
Most stars in the universe (about 95%) will end their lives this way; the rest will die as supernovae.
NAME: IC 1295.
WHAT IS IT?: Planetary nebula.
HOW FAR AWAY IS IT?: About 3300 light years.
HOW BIG IS IT?: 1.7’ X 1.4’ arcminutes on the night sky.
APPARENT MAGNITUDE?: 12.7 or +12.7.
WHERE IS IT? (General): Southern constellation of Scutum (The Shield).
WHERE IS IT? (Exact RA/DEC J2000): RA 18h 54m 37.25s / DEC -8° 49′ 39.41″.
ESO page for this image with information: http://www.eso.org/public/news/eso1317/
ESO page for this image: http://www.eso.org/public/usa/images/eso1317a/