Novae and Type Ia Supernovae

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White dwarf stars can cause sudden outbursts called novae, and even do a special kind of supernova. If we combine the common nature of white dwarfs and the fact that most stars are in binary (or more) systems, then we can see that as stars die, they can interact. Novae and Type 1a supernovae are the result. This is part of my complete intro Astronomy class that I taught at Willam Paterson University and CUNY Hunter.

White Dwarfs

White Dwarfs, Neutron Stars, and Degeneracy

Dwarf nova

Nova

GK Persei

Nova Per 1901

Artist's impression of vampire star

Study confirms that stellar novae are the main source of lithium in the universe

Accretion Disk Around Binary Star System WZ Sge

Planetary nebulae

White Dwarf supernova simulation images

The Nobel Prize in Physics 2011

Supernovae, Dark Energy, and the Accelerating Universe

Improved Hubble data provide fresh evidence for new physics in the Universe

This is part of an entire online introductory college course. This video series was used at William Paterson University and CUNY Hunter in online classes as well as to supplement course material. Notes and links are present in the videos at the start of each lecture. In this lecture series, I talk about the end states of stars. The amazing white dwarfs and neutron stars. White Dwarfs are fascinating end states of Solar-mass (or slightly bigger) stars. Sirius "b" is among the closest known and we know many things about these oddball planet-sized stars from the Dog Star's dog. Next, if we combine the common nature of white dwarfs and the fact that most stars are in binary (or more) systems, then we can see that as stars die, they can interact. Novae and Type 1a supernovae are the result. White dwarf stars can cause sudden outbursts called novae, and even do a special kind of supernova. Then we go to some of the most amazing objects in the universe that are still things are neutron stars. Often looked at in astronomy as the thing on the way to black holes, neutron stars are the most extreme objects in the universe composed of what we might still call normal matter. Black holes are another thing. These boundary objects have wild properties and have extreme effects on their surroundings. Forged in the instantaneous fire of a core-collapse supernova, they are awesome objects. Finally, neutron stars make themselves known by their spin. They create a huge magnetic dynamo that powers the emissions seen in X-rays and gamma-rays. The result is a pulsar or magnetar. The Crab Nebula is the classic example of these amazing objects. They can also do similar thing like we saw with novae, but with much more extreme results: the kilonovae.

[thetobi]

That's a question I've been asking for a while is "how exactly do white dwarves explode?". Thanks to the slides and your explanation, I now know something I've been wondering for at least a decade :)

[aboodfarhood]

The beautiful physics of the stars without equations! Wow!

[alansilverman]

How is it that white dwarfs are able to accrete as much material as needed to explode as a Ia supernova without first expelling that material in successive dwarf novae events?

[robertethanbowman]

Even you simplify that stars stop at Iron, when the actually stop at two Silicon-28 combining to Nickel-56. Then it is the decay back to Iron-56 that keeps the supernova bright.

[judhajeetbasu]

Thank you for the nice lecture. Very informative.

[charlesworthington]

Thank you... Now i know how novas can repeat more than once.

[ComradeArthur]

Take a generic white dwarf in a one star system. For example, our solar system in a few billion years. Over trillions and trillions of years it will simply cool down... but is something else going on? This white dwarf is drifting through space... and there's dust and gas in space. It's going to snag some of it and get a little bit more massive. Will it ever get massive enough to blow up? Say.. in 50 or 100 trillion years?

[scottdorfler]

I asked Fraser Cain Sunday night to explain why some white dwarfs in binary systems produce Nova and others produce Type 1A Supernova. Then I thought, I'll bet Jason Kendall has a comprehensive video explaining this. I was right!!!😂

[docholiday]

The progenitors of type 1a are polar (highly magnetic) white dwarfs.

The mass stolen from a companion star is sucked in at the polar regions. It accumulates INSIDE the stellar corpse.

Like a giant pressure cooker, they all have the same breaking point, the same interior capacity (230 million Gauss).

The chandrasekhar limit is the net minimum mass of a pulsar. It has nothing to do with the explosion.

[jeffcook]

Always thought I wasn't smart enough for all this in spite of a BS Chemistry from CSUN in 1979. Now I'm 71, suffered my first concussion five years ago and with these lectures, I'm finally understanding at least the basics of cosmology. By the way from about 69-73 I catalogued about 30 of the Messier objects with a 3 inch refractor as a teenager.

[nathankristofik]

I'm going a bit crazy here. The slide (15:08) says "as the density rises the temperature does not increase" in reference to white dwarfs is that a mistake? Did you mean to say the pressure does not increase? I thought this whole thing was about how the temperature increases to a point that it starts to ignite carbon oxygen burning. If the temp doesn't increase how does it reach a new ignition point?

[docholiday]

The progenitors of type 1A are polar white dwarfs (like AN Ursae Majoris B.)

The chandrasekhar limit has nothing to do with why the explode. 1.44 S.U. is merely the minimum net weight required to form a pulsar. 🤠✌️

[vernonvouga]

Hey dude, do white dwarfs produce magnetic fields that can be detected by the technology that we have now? I am so darn curious about the correlation between magnetic fields and the rest of matter, because it seems to be from my point of view and observations that magnetism is just as important. Static electricity creates magnetism, right? I'm not trying to be a troll I'm just bored and I love astronomy

[andyd.]

"Don't tell DC comics..." ha! Great presentation🌟

[DMatterMakers]

I like to think I have a fairly decent grasp of this material, but I keep questioning one main thing. When we talk about inflation and the acceleration of the universe, it always goes back to charts showing that the further away we look (aka the further back in time we look) the faster the universe is expanding. I guess I am just not grasping this simple concept, because I would expect to see galaxies further away moving away faster due to the fact that those images are further back in time. I would expect to see faster movement closer to the beginning of an "explosion" than (further away / earlier in time, in relative terms) than I do looking at objects closer. Am I just missing that the time adjustment for distance is compensated for in these diagrams? Because if not, then this is what I would expect to see in an explosion that is slowing down currently.

[w.allencaddell]

When a white drawf explodes, does it make it the brightest light in the universe? Can it be seen?

[Jo-qsri]

My question is; to what extent have you been able to measure expansion between the earth and our moon?

[johnbassam]

this is nice i’d love to be your student in the future

[Dragrath]

There is now evidence that there are several classes of Type Ia supernovae one type the single degenerate class happens as you described by mass transfer back and forth as a binary pair ages until a white dwarf reaches the Chandrasekhar limit are also able to form by the merging of two white dwarfs that exceed Chandrasekhar limit. The latter type of type Ia supernovae adds a complication to using type Ia supernovae as white dwarf mergers can actually exceed 1.44 solar masses depending on the mass of the two white dwarfs. They have resolved this issue by determining methods to tell the two types of type Ia apart but it shows how much more complex the situation has gotten. Two further weird oddities are type Iax where the star accretes helium which can result in a weaker explosion that may potentially be weak enough that some part of the star can survive.



Another really weird white dwarf system is the until recently theoretical super-Chandrasekhar mass carbon-oxygen white dwarf where two massive white dwarfs merge together with a resulting mass sufficient to hold together and avoid collapse due to the ignition of carbon fusion in its interior. Earlier this year a team of Russian astronomers published in Nature that using Gaia parallax measurements we able to identify the WO type "Wolf Raynet star" WS35 is 3.07 kpc away and is most likely one of these stars that will eventually undergo a core collapse type Ic supernovae and likely a neutron star remnant.

[markphc]

Fascinating, where do we get all the elements between magnesium, silicon and iron, I don’t see any mechanism for the production of eg: vanadium