What are the differences among Type I and Type II supernovae??

Hi omarina,
That's a very general question!
It would require an answer too long for this kind of forum.
You might make a better start by doing some research in a textbook, or on sites such as Hyperphysics (http://hyperphysics.phy-astr.gsu.edu/hbase/astro/snovcn.html), NASA (http://www.nasa.gov/worldbook/supernova_worldbook.html) (and another NASA page (http://imagine.gsfc.nasa.gov/docs/science/know_l1/sn_overview.html)), Wikipedia (http://en.wikipedia.org/wiki/Supernova#Classification), or even Google (http://www.google.com.au/search?hl=en&q=type-i+type-ii+supernova+site%3A.edu&meta=).

If you want to ask or discuss anything a bit more specific, please do!

Pete

Or you can ask Mr. Paul W. Dixon, PHD. :D

I think there are three types of novae, but would not defend this view against somebody more knowledgeable than I.One type occurs at the end of the life cycle of stars larger than Sol, but not extremely massive.


Another type occurs at the end of the life cycle of extremely massive stars.


The third type occurs in a binary system after one star has become a neutron star. The neutron star starts collecting mass from its companion. At some point the extra mass makes the neutron star unstable, resutling in the third type of nova.If anybody has another explanation, I would be interested in hearing about it.

One difference is that Supernovae type II are less luminous than Supernovae type I

Type I are usually divided into various categories: type Ia, Ib, Ic,... Type Ia are due to the explosion of a white dwarf. On the contrary, type II are due to the explosion of masive stars of Population I

Yet another difference is that type I lack hydrogen lines in their emission spectra, those lines certainly appear in type II emission spectra

Dino is correct that the type depends heavily on the mass of the original star. I too might be wrong but...

Origin of one type:
When a star burns up all the available fuel the explosive pressure that stops it collapsing reduces. As it shrinks under its own gravity as it heats up, it keeps getting hotter until the next stage of fusion burning kicks in, this releases a huge amount of energy and kicks out the outer gas layers of the star, these expand and cool and form planetary nebula (very pretty).

The more massive a star the more burning sequences it goes through (also very pretty), until the Chandrasekhar limit is reached (>1.4 times solar mass) where a neutron star or, if very massive, a black hole is formed. This releases a huge amount of energy creating a VERY VERY pretty picture.

I think it might be a good idea to note that all heavy elements larger than Iron are created in supernova explosions... thats how we have natural uranium and all the other good stuff that radioactively decays! (except like half the elements above iron have only been created by man.

Tristan: Not sure what you mean by the following.except like half the elements above iron have only been created by man.Periodic Table software I have indicates the following.25 elements below Iron (26), when arranged by atomic number.
66 Elements: 27-92 occur naturally, although a few of these are extremely rare.
11 Elements: 93-103 are man made.My software might be missing some elements created since about 1997.

What are the differences among Type I and Type II supernovae??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/cgi-bin/nph-iarticle_query?1941PASP...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

Dinosaur: Yeah, i just overexagerated for some stupid reason

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



The explanations that I have read of type Ia say that is the white dwarf in the binary system the star that explodes to cause the supernova. The companion star in the binary system is typically a red giant. The white dwarf is accreting material from the companion star, until the white dwarf explodes

You are correct. On re-reading what I wrote I see I have phrased it ambiguously. The companion is undergoing destruction at the 'hands' of the white dwarf, but before this destruction is complete the white dwarf anihilates itself and much/most/all of its companion.

I think there are nova-like events due to a neutron star in a binary system aquiring mass from its companion

I think it might be a good idea to note that all heavy elements larger than Iron are created in supernova explosions...Most are very quickly (cosmic time scales) produced as you suggest, but a small fraction are "slow cooked" in endothermic reactions deep inside the late stages of very large stars.

ugggghhhhh....got a 60% on my astronomy mid-term.... class average was 55%.

Just to make matters even more confusing, some of the folks I work with have a paper coming out in Astrophysical Journal in a couple months on the discovery of another "hybrid" supernova exhibiting characteristics of both Ia and IIn types.

The astro-ph preprint service has it here (http://lanl.arxiv.org/abs/astro-ph/0606499) for the curious who like big words more than I do. ;)