Difference between Supernova vs. Nova?

[pixel01]

Hi all,

In this article: http://www.space.com/scienceastronomy/091105-new-supernova.html ,
they mentioned supernova and nova.
Anyone tell me the difference between the two 'cosmic explosions'

Thanks

 

[Vanadium 50]

It's in the eighth paragraph of the link you posted. Is there something specific about that which you find confusing?

 

[pixel01]

It's in the eighth paragraph of the link you posted. Is there something specific about that which you find confusing?

Thanks Vanadium.
As I understand, a supernova is about 1000 times stronger than a nova. But what is a nova?
Is that a 'weak' supernova ?

 

[Vanadium 50]

But what is a nova?

The article you posted says: "This process is akin to a nova, where matter, mainly hydrogen, falls onto a star, slowly building up and then exploding, but with less force then a full-fledged supernova. "

What's causing you trouble with that definition?

 

[pixel01]

The article you posted says: "This process is akin to a nova, where matter, mainly hydrogen, falls onto a star, slowly building up and then exploding, but with less force then a full-fledged supernova. "

What's causing you trouble with that definition?

My puzzle is that the very definition above describes a supernova type I, so what is a nova that is one thousandth the strength of a supernova?

By the way, before reading this article, you knew that definition of a nova?

Thanks

 

[mgb_phys]

There isn't really much in common between a nova and a supernova other than they make a star brighter (nova = new star)

A nova is where some material falls onto the surface of a compact star which makes it 10-100% brighter for a short time - but the star isn't really affected.
A supernova is the end of life of a large star where it runs out of fuel in the core and there is no reaction to support the rest of the star. The entire star collapses and creates more energy in a few minutes than the star generated in the 10bn years of it's life. There is only a small bit of the star left afterward s a neutron star

 

[Vanadium 50]

In a nova, hydrogen from a nearby star falls onto a white dwarf star until it ignites and blows off in an expanding shell. Essentially, a white dwarf turns back into an ordinary star for some weeks.

In a Type I supernova, enough material falls on this white dwarf to destroy it, turning it into a neutron star.

 

[Chronos]

Here is a brief, non-technical discussion you may find interesting
http://www.astrophysicsspectator.com/topics/supernovae/

 

[Ophiolite]

These notes may be of some interest to you.

Supernovae Spectral Types
There is more than one type of supernova. Rudolph Minkowski set up a classification system based upon some major characteristics of their spectras. [Minkowski, R., Spectra of Supernovae, Publications of the Astronomical Society of the Pacific, Vol. 53, No. 314, p.224. http://articles.adsabs.harvard.edu/...ASP...53..224M]
Type I have no hydrogen lines in their spectra, while Type II do. Later, the Type I supernovae were subdivided as follows:

Type Ia has no helium lines, strong silicon lines at maximum magnitude and iron group emission lines in its later stages.
Type Ib has helium lines and no silicon lines at maximum magnitude. Often these will be about 1 - 2 magnitudes fainter than Ia types.
Type Ic has no helium lines and no silicon lines at maximum magnitude. Oxygen and calcium lines my appear in the later stages.

The Type II supernovae are subdivided on the basis of whether their brightness plateaus, then falls in a regular manner (Type IIp), or reaches a maximum and falls off from this, again in a linear way (Type IIL).

Supernovae Causes
Supernovae are caused by one of two principal mechanisms:

Destruction of a stellar companion to a white dwarf in a contact binary system. These account for the Type 1a supernovae.

Catastrophic demise of massive stars (more than ten times solar mass) account for all other supernovae types. The differences between the spectral types are due to variations in the specific history of the star, sometimes related to the effects of nearby companions.

Ib has lost its hydrogen envelope, while helium ‘burns’ on a carbon-oxygen core.
1c has also lost its helium.

The loss of hydrogen and helium is either due to very strong solar winds, or to gravitational stripping by close companion stars.

Type II supernovae have retained at least some of their hydrogen atmosphere.

Supernova Remnants
The typical remnant of a supernova will be a very dense object, either a neutron star, or, if sufficiently massive, a black hole. This is not thought to be the case for Type 1a supernovae, the type produced in contact binary systems. In these instances no central object survives the event.

Supernovae Numbers
Since 1885 over three and a half thousand supernovae have been observed. A current list is maintained here.
www.harvard.edu/cfa/ps/lists/Supernovae.html[/URL]