The next supernova?

[JohnDenim]

Will we ever see one in our lifetime?

I know Eta Carinae is not far off, at about 100 times the size of our sun.

What an experience it would be to see a star die.

Am I right in thinking all of the nebulae that we see are all dying stars?

[John]

There have been lots of supernovae in my lifetime and I've seen two of them - one at the SGL5 star party last April and the latest one, SN2011b, a month or so ago. I think ones that can be seen with amateur scopes are less common but still occur now and then.

Some nebulae are the results of supernovae but some are star forming regions (eg: M42) so contribute to the birth of stars.

[Nexus 6]

Will we ever see one in our lifetime?

its possible one could happen at any second, as there no way of knowing for sure when one may happen its means there's always some chance, of course like you say we have detected signs from possible candidates, Eta Carinae and then there's Betelgeuse

[Ad Astra]

Statistically, the probabilities are one supernova per galaxy per century. We haven't had one in the Milky Way in almost 500 years - so we're due!

Absolutely no way to predict exactly when any star will go. Betelgeuse, Antares and Aldebaran are all red giants that might go "pop" in our lifetimes. More likely we would suddenly see an astra nova or 'new star' - an old star too far away for any of us to notice suddenly becomes a brilliant supernova in the skies of Earth.

I can't wait!

Dan

[Skylook123]

Will we ever see one in our lifetime?

I know Eta Carinae is not far off, at about 100 times the size of our sun.

What an experience it would be to see a star die.

Am I right in thinking all of the nebulae that we see are all dying stars?

We are certainly late for one in our own galaxy. However, other galaxies do have them. I've observed a dozen or so over the years. Just as with comets and other phenomena, the International Astronomical Union will report all detected supernovae in it's circulars, but you have to pay to get on the list; the circulars are pretty stale by the time we folk get access to them, unless we sign up for the paid reports. The word does get out pretty quickly, though, in a variety of sources such as Spaceweather.com, Astronomy and Sky and Telescope web sites, even here in the Lounge. I find the Latest Supernova web site (link below) helpful in identifying supernovae available for observing:

Linky ==> Latest Supernovae

As to the nebulae we see around the sky, there are five types. Three types are not related to stellar evolution: emission nebulae (gas clouds energized by close high energy stars such as The Orion Nebulae), reflection nebulae (gas clouds reflecting light from stars close enough to provide light, but far enough away that no electron stripping is going on, such as The Swan), and dark nebulae (just dust getting in the way of the background). Emission nebulae tend toward the red end of the spectrum due to the hydrogen atoms being disrupted then reformed due to the high energy of a nearby star or star field. Reflection nebulae tend toward the blue, because of the nature of the light spectrum and absorbtion. Dark nebulae are just that; inky dark spots in the field, such as the Milky Way dark lane, or the dust in the path of the light from The Swan that causes the swan head shape. In infrared imaging, stars behind the dark nebulae can be imaged since the infrared spectrum does penetrate through the dust.

That leaves the final two nebulae (Greek for clouds, BTW). Planetary nebulae are the cast off outer shells of stars that are approximately the size of our sun at the end of their lives. These end of life artifacts are not caused by catastrophic "explosions" due to the stars' collapses; they are more like sneezes, as the star uses up about 75 percent of its hydrogen from the core out and can't fight the gravity collapse. The collapse causes a new nuclear reaction in the helium that has been forming over the billions of years of life, making nitrogen and oxygen from the helium in the core, whilst the hydrogen in the outer part of the star is still merrily cooking away as well. This extra energy in the core causes the star to grow into a huge red giant; giant because of the energy forcing the new size, and red because the energy is distributed throughout such a large volume that the temperature drops leaving the star in a red state. Our sun, in this phase, may grow to be as large as the orbit of the earth, or larger. This is the end of life of a star from bigger than half of our sun's mass up to maybe 3 or 4 times as massive. When the helium is mostly used up, another collapse happens and a new nuclear reaction happens among the products. From here it gets very specialized to the mass of the star and the constituent elements. Many possible paths it can take. Eventually, every one of these collapses causes a sneeze off of several percent of the outer layer. At the end, these sneezes will have blown off a good percent of the star's contents which are spreading outward, leaving behind a white dwarf glowing for many billion years due to the residual heat and some small amount of remaining fusion. Eventually, it will burn out many billion years later but the matter sneezed off will spread around the universe, or at least the galaxy, and form the seeds for planets, asteroids, comets, and even mix in with hydrogen in later generation stars. We are star stuff! There are something over 1,500 or so of these in the NGC/IC catalogs, with interesting shapes and names such as The Ring, The Dumbbell, The Helix, Saturn Nebula, Blue Snowball, Ghost of Jupiter, and many others. Generally they can be seen easier with an O-III filter due to the ionized oxygen in the cast off material. An Ultra High Contrast filter does well, also, since this filter includes the hydrogen beta lines and thus the ionized hydrogen also shed.

That leaves Super Nova Remnants, the most famous being The Crab and The Veil. If the source star is larger than three or four times the mass of our sun, it does not get to go through repetitive cycles of collapse and element formation, and growth to a red giant. It only gets one collapse, due to the mass involved, and catastrophically ends its life in a violent reaction. While a planetary nebula's generation may lead to elements as high as iron, the rest of the elements get formed in a supernova. This is because iron is endothermic; it can not be forced into a nuclear fusion process by heat and pressure, so that's where the benign end of life ends. With the more massive stars, the supernova event includes the heavier elements in its products. Depending on the mass of the parent star, the remains might be a neutron star, a soup of neutrons forced to exist by gravity squeezing the electrons and protons together in the remnants of the former star. Or, if the source star was very massive, there may be so much matter left over after the cataclysm that a black hole will form. Thus, a star ends its life by just burning for many billions of years if it is less than half or so of the mass of the sun, or as a planetary nebula formed by benign sneezes after about 12 or 13 billion years of life, spending a few hundred million years in this state, or catastrophically leaving behind a neutron star or a solar mass black hole.

Planetary nebulae are visible for many thousands of years as the white dwarf star at the center sends out much of its light in ultraviolet, which causes the greenish blue reaction in the visible band by the cast off outer material Supernovas are visible brightly for a few weeks or so, sending out more light for that time than their entire parent galaxies. Sometimes there are stars near by to energize the SNR remnants in our galaxy, or the neutron star, but in other galaxies our only glimpse is with the supernova burst. After that, they will dim out.

This is a really simplistic explanation, and there are many exceptions and clarifications that need to be made in all of the cases. For we simple astronomers, I find planetary nebulae fascinating since there are so many visible to us, our sun will end up in this fashion, and the shapes are so unique, each one dependent on the magnetic field of the parent white dwarf for the image we see. Plus, we are star stuff!

[yeti monster]

Phew! Thanks for that Jim. Being a simple soul from the back woods, such explanations are much appreciated, so often folk with such learning appear to belittle those without.

[x6gas]

Of course, the next super nova we'll see has already happened!

I still think it's a amazing that the heavy elements that we see around us - and that we are made of - were formed in a distant star. As Jim says, we're star stuff!

[Ad Astra]

Excellent explanation, Jim!

Wanna come and Guest-Lecture in my class sometime?

Dan

[Mark at Beaufort]

Thankyou Jim for that useful link to obtain the latest information on supernovae.

Your explanation is also very helpful and it explains the various types of nebulae in a very useful and concise way.

Thanks

Mark

[dharma66]

Superb post Jim, thanks!

[Skylook123]

Excellent explanation, Jim!

Wanna come and Guest-Lecture in my class sometime?

Dan

Thanks, Dan! Would love to, if I ever get to your part of the west; can't resist an audience. Nowadays tied up with some family and work pressures, but looking forward to retiring and spreading the science to the masses. Too much dadgum fun.

[Skylook123]

Thank you everyone for the kind comments. I do have a tendency to ramble on; a supervisor once gave me a desk name plate that said "Don't ask him the time or he'll build you a clock."

I've been learning and teaching this in public outreaches for almost 20 years, and still love the exploration. It is only a Google search away, nowadays!

[Nexus 6]

I do have a tendency to ramble on; a supervisor once gave me a desk name plate that said "Don't ask him the time or he'll build you a clock."

Brilliant account and a very enjoyable read on a spectcular field of astronomy, thanks for sharing Jim

[Skylook123]

Thank you, Alan, it is very good to know that the information is of some help. I found that when I learn a new subject, I don't really understand it until I can present it clearly to someone else. In fact, that is usually my final step in learning; try to present the information in a way that stands alone, as simply as possible.

So, to answer JohnDenim's question concisely, supernovae happen frequently in the universe, but not recently in our neighborhood. Statistically, our galaxy is due for one and while it would be a remarkable experience to witness a "local" event, let's hope one is not too close; the radiation would be hazardous to our health!

[Nexus 6]

won't make any difference if one has appeared out of the blue, the weather over here would put a stop to our chance's of observing it.