Surepnovae

There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?

chupacabra wrote:

There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?

I asked the same thing concerning globular star clusters. We should be
seeing supernovae 'all the time' in and around the vicinity of globular
star clusters because they all contain a minimum of 1 million stars, but
we do not. I got no reply except insults and posts telling me I was a
kook. Obviously the simplistic models held onto by astronomers and
comsologists are severely lacking when even the uneducated see through
the holes and gaps in their theories.

"chupacabra" wrote in message
om...
There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?

Not every star ends in a nova, and very few in
a supernova.

On 10 Aug 2004 18:02:47 -0700, chupacabra wrote:

There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?

The reason is simple. Not all stars blow-up supernova style. Most of them,
including our Sun, die a more peaceful and prolonged death.
BTW, the stars that do go supernova have lifespans in millions, not
billions of years.

--
The butler did it.

"chupacabra" wrote in message
om...
There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?

Oh, and btw... some estimates are up to 10 times yours. Serge Brunier's
"Great Atals of the Stars" claims estimates of almost 1,000 billion
(i.e., 1 trillion) stars in our galaxy (and also in the Andromeda
galaxy).

"chupacabra" wrote in message
om...
There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?\

Not every star goes supernova. We also cannot see the whole of our own
galaxy.

However, supernovas are spotted all the time in other galaxies, often by
amateurs.

http://www.supernovae.net/snimages/

On 10 Aug 2004 18:02:47 -0700, (chupacabra) wrote:
There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?
******************* ***********************
You might wish to check out some of the basic qualifications for a
SuperNova.
Just one qualification might well be the mass of the star.

In addition, astronomers classify supernovae into two main types.
These are Type I and Type II.
It strongly appears that supernovae come about from two very
different classes of stars: massive ones and old, non-massive ones.
Type I supernovae do not show any hydrogen in their spectra.
In contrast, Type II supernovae have the element hydrogen in their
spectra.

VERY Basic EXAMPLE: consider more massive stars ( equal to or
greater than 8 solar masses).
Here the sequence of nuclear fusion makes a smooth progress from what
we normally might see, the very simplest reaction of hydrogen nuclei
to form helium nuclei, up to far more complicated reactions.
At or near the end-stage, the reaction involves the synthesis of
silicon nuclei into iron nuclei.
That can be a problem...
The iron nucleus is stable; very stable.
It does not take kindly to attempts at fusing into any heavier
nuclei.
That iron nucleus must be forced, must be compelled.
This is done by applying force; lots and lots and lots of force
through a whole lot of energy.
THUS, when the star's innermost heart, when its central core, has
become iron nuclei, that core --- where the star has been busy
producing massive amounts of energy over the years, no longer is able
to produce energy.
Without that little bit of effort, the central core cannot support the
star.
The core can no longer support the crushing force of gravity.
And suddenly, all of the mass of the star, lacking that needed
support, begins collapsing, crushing the core...
There are some very interesting things that are happening during this
time.
At a certain point the core collapse abruptly halts.
Amazingly, with all that is happening, the core rebounds.
That releases, in a very brief moment of time, unimagineable
energy.... That energy goes ripping upward, through all of the layers
of the dying star with such force that the star is demolished, leaving
a witch's brew of transformed elements spewing out into space and,
back within the environs where the star once was, as a result of some
of the interesting reactions, there might well be a neutron star.

To consider your question, you might try to discover how many stars in
a galaxy are more massive than Sol: how many are at least 5X as
massive so they might enter the lists to qualify for consideration as
a Supernova...
---Mac

"Mac" wrote in message
news
On 10 Aug 2004 18:02:47 -0700, (chupacabra) wrote:
There are around 100 bln. stars in our Galaxy. Since the average
livespan of a star is c. 10 bln. years, in means that around 10 stars
should explode every year. Contrary to this, the explosion of a
supernova in Milky Way galaxy is a very rare event, the last one
happened in 17-th century. What's amiss?
******************* ***********************
You might wish to check out some of the basic qualifications for a
SuperNova.
Just one qualification might well be the mass of the star.

In addition, astronomers classify supernovae into two main types.
These are Type I and Type II.
It strongly appears that supernovae come about from two very
different classes of stars: massive ones and old, non-massive ones.
Type I supernovae do not show any hydrogen in their spectra.
In contrast, Type II supernovae have the element hydrogen in their
spectra.

VERY Basic EXAMPLE: consider more massive stars ( equal to or
greater than 8 solar masses).
Here the sequence of nuclear fusion makes a smooth progress from what
we normally might see, the very simplest reaction of hydrogen nuclei
to form helium nuclei, up to far more complicated reactions.
At or near the end-stage, the reaction involves the synthesis of
silicon nuclei into iron nuclei.
That can be a problem...
The iron nucleus is stable; very stable.
It does not take kindly to attempts at fusing into any heavier
nuclei.
That iron nucleus must be forced, must be compelled.
This is done by applying force; lots and lots and lots of force
through a whole lot of energy.
THUS, when the star's innermost heart, when its central core, has
become iron nuclei, that core --- where the star has been busy
producing massive amounts of energy over the years, no longer is able
to produce energy.
Without that little bit of effort, the central core cannot support the
star.
The core can no longer support the crushing force of gravity.
And suddenly, all of the mass of the star, lacking that needed
support, begins collapsing, crushing the core...
There are some very interesting things that are happening during this
time.
At a certain point the core collapse abruptly halts.
Amazingly, with all that is happening, the core rebounds.
That releases, in a very brief moment of time, unimagineable
energy.... That energy goes ripping upward, through all of the layers
of the dying star with such force that the star is demolished, leaving
a witch's brew of transformed elements spewing out into space and,
back within the environs where the star once was, as a result of some
of the interesting reactions, there might well be a neutron star.

To consider your question, you might try to discover how many stars in
a galaxy are more massive than Sol: how many are at least 5X as
massive so they might enter the lists to qualify for consideration as
a Supernova...
---Mac

Thank you for that very clear and concise explanation. Science is wonderful
isn't it?