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Main
Date: 13 Jul 2007 04:33:41
From: Radium
Subject: Definition of the sun's "death"?
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Hi:
I just don't understand why the expansion of the sun into a red giant
would be classified as the sun's 'death'. As a red giant, the sun will
very much be alive as it is today. It will burn helium instead of the
hydrogen it burns today.
My definition of the "death of the sun", is when the sun ceases its
nuclear fusion. Fusion is what gives the sun its life.
Best,
Radium
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Date:
From: Martin Brown
Subject: Re: Definition of the sun's "death"?
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Date: 13 Jul 2007 23:28:41
From: Jim Klein
Subject: Re: Definition of the sun's "death"?
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But we won't be here to enjjoy it.
Jim
Radium <glucegen1@gmail.com > wrote:
>Hi:
>
>I just don't understand why the expansion of the sun into a red giant
>would be classified as the sun's 'death'. As a red giant, the sun will
>very much be alive as it is today. It will burn helium instead of the
>hydrogen it burns today.
>
>My definition of the "death of the sun", is when the sun ceases its
>nuclear fusion. Fusion is what gives the sun its life.
>
>
>Best,
>
>Radium
James E. Klein
jameseklein@earthlink.net
Engineering Calculations
http://www.ecalculations.com
ecalculations@ecalculations.com
Engineering Calculations is the home of
the KDP-2 Optical Design Program
for Windows.
1-818-507-5706 (Voice and Fax)
1-818-823-4121
"KDP2, not quite easy enough for a Caveman to use" :-)
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Date: 14 Jul 2007 00:05:31
From: Davoud
Subject: Re: Definition of the sun's "death"?
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Radium wrote:
> >I just don't understand why the expansion of the sun into a red giant
> >would be classified as the sun's 'death'. As a red giant, the sun will
> >very much be alive as it is today. It will burn helium instead of the
> >hydrogen it burns today.
> >
> >My definition of the "death of the sun", is when the sun ceases its
> >nuclear fusion. Fusion is what gives the sun its life.
Since such terms as "birth," "life," and "death" are figurative terms
when used in reference to inanimate things, they have no real meaning.
They make for nice romantic language, however, and I'm not at all
opposed to these words' use in this context. But if we're talking about
the facts, the sun was not born, it is not alive, and it will not die,
even when the last atoms have been fused.
Our ilk will be long gone when the sun stops shining and as near as I
can tell there will be no one to mourn us. No big thing. Everyone dies.
Davoud
--
usenet *at* davidillig dawt com
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Date: 14 Jul 2007 00:46:00
From: Chris L Peterson
Subject: Re: Definition of the sun's "death"?
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On Sat, 14 Jul 2007 00:05:31 GMT, Davoud <star@sky.net > wrote:
>Since such terms as "birth," "life," and "death" are figurative terms
>when used in reference to inanimate things, they have no real meaning.
>They make for nice romantic language, however, and I'm not at all
>opposed to these words' use in this context. But if we're talking about
>the facts, the sun was not born, it is not alive, and it will not die,
>even when the last atoms have been fused.
The terms need not be figurative. Just look them up in any ordinary
dictionary; they do not apply only to living things. It is not
necessarily figurative to say that a star is "born", "lives", and "dies"
(although it may be taken as such depending on the style of writing
involved).
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 14 Jul 2007 07:58:37
From: Davoud
Subject: Re: Definition of the sun's "death"?
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Davoud:
> >Since such terms as "birth," "life," and "death" are figurative terms
> >when used in reference to inanimate things, they have no real meaning.
> >They make for nice romantic language, however, and I'm not at all
> >opposed to these words' use in this context. But if we're talking about
> >the facts, the sun was not born, it is not alive, and it will not die,
> >even when the last atoms have been fused.
Chris L Peterson:
> The terms need not be figurative.
Yes, they are necessarily figurative when applied to inanimate things.
> Just look them up in any ordinary
> dictionary; they do not apply only to living things.
That is indisputably true. But that usage is figurative. Not wrong in
any way, but figurative.
> It is not
> necessarily figurative to say that a star is "born", "lives", and "dies"
> (although it may be taken as such depending on the style of writing
> involved).
You may have confused "very commonly used" with "not figurative." No
matter how often these terms are used to refer to inanimate things,
they are figurative. Don't misunderstand me; I am not arguing that this
figurative usage is incorrect, because it is not. Furthermore, I attach
no importance to this, and my comment on the sun was essentially
parenthetical. I know of no other way of referring to the "life" cycles
of stars that is as simple and elegant as "star-birth," "lifetime,"
"star-death," and such like. But I know that you are a stickler for
detail, as anyone who considers himself to be omniscient must be. The
literal meaning of "to be born" is "to have been carried" (borne) --
usually in a womb -- and then to have exited the womb --usually via a
birth canal -- as a living animal. Unless our hard-won knowledge of
star-birth is profoundly wrong, stars are "born" only in a figurative
sense. Likewise "shelf-life," "half-life," "stellar nursery" (who
breast-feeds them?) and a host of similar figurative expressions.
The language would be very poor indeed without figures of speech. Look
at how people on Usenet who are unable to recognize figurative speech
(and hyperbole and irony and other non-literal speech) disrupt a Usenet
thread. They come across as dolts. I was recently taken to task by such
a dolt in this forum for a humorous remark to the effect that some
amateurs image from 15,000-meter mountains in the Southwest! The idiot
thought that I believe that such mountains exist! (In my reply I said
"Of course, there /are/ a few 15,000-meter mountains in Arizona and New
Mexico, the precise locations of which are known only to a tiny group
of very elite amateurs who are conspiring to keep the locations secret
from the rest of us. People like Chris Peterson, who actually owns such
a mountain :-)"
Davoud
--
usenet *at* davidillig dawt com
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Date: 14 Jul 2007 14:00:53
From: Chris L Peterson
Subject: Re: Definition of the sun's "death"?
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On Sat, 14 Jul 2007 07:58:37 GMT, Davoud <star@sky.net > wrote:
>You may have confused "very commonly used" with "not figurative." No
>matter how often these terms are used to refer to inanimate things,
>they are figurative.
I would not consider them so. Certainly, the _original_ meaning of these
terms is such that their first application to inanimate things should be
considered figurative. But language evolves, and words come to have new
meanings- meanings which cannot be considered figurative except in the
most narrow sense of that word. They even become the basis of new words.
Particles have "half-lives" and "lifetimes". Are these terms, which
don't even have any synonyms in scientific usage, figurative, as well?
Can a word be figurative if no literal alternative even exists?
>The literal meaning of "to be born" is "to have been carried" (borne) --
>usually in a womb -- and then to have exited the womb --usually via a
>birth canal -- as a living animal.
That is not the literal meaning of "to be born", but the meaning of the
original word. Perhaps we just have different views of "figurative".
"Planet" literally means (or meant) "wanderer". Would you consider the
usage figurative to talk about a planetary body orbiting another star?
(I do understand that we have no disagreement on usage, and that this is
nothing but a pleasant discussion about the fine points of our rich and
complex language. Brian, care to give your thoughts? I know you must be
lurking on this thread <g >.)
>I was recently taken to task by such
>a dolt in this forum for a humorous remark to the effect that some
>amateurs image from 15,000-meter mountains in the Southwest! The idiot
>thought that I believe that such mountains exist!
I think you're being a bit harsh. Curtis hasn't demonstrated himself on
this group to be a dolt. I read that part of your post a couple of times
to convince myself you meant the figure humorously. Since the apparent
joke in the sentence seemed to be the comment about "gray sky", it sort
of left the "15,000 meter" bit orphaned. It wasn't entirely clear it
wasn't some sort of typo.
BTW, you're quite wrong about those of us living at hypoxic altitudes
being unfamiliar with "gray sky". We experience an hour or more of just
that every day, at dusk and dawn. Not to mention the annoying gray light
pollution from the Milky Way, zodiacal light, and gegenschein that is
always interfering with imaging.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 15 Jul 2007 03:20:21
From: Davoud
Subject: Re: Definition of the sun's "death"?
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Davoud:
> >You may have confused "very commonly used" with "not figurative." No
> >matter how often these terms are used to refer to inanimate things,
> >they are figurative.
Chris L Peterson:
> I would not consider them so. Certainly, the _original_ meaning of these
> terms is such that their first application to inanimate things should be
> considered figurative. But language evolves, and words come to have new
> meanings- meanings which cannot be considered figurative except in the
> most narrow sense of that word. They even become the basis of new words.
> Particles have "half-lives" and "lifetimes".
That is all perfectly true, except that "figurative" does not have a
narrow sense. In language it just stands in contrast to "literal" and
and words such as "life" and "death" must be figurative if they apply
to non-living things.
> Are these terms, which
> don't even have any synonyms in scientific usage, figurative, as well?
> Can a word be figurative if no literal alternative even exists?
I /think/ it can. But so what? We say "This compound has a shelf-life
of six months." We don't have to say "This compound has a figurative
shelf-life of six months." So, while the usage /is/ figurative, that
fact has no practical importance. The speaker doesn't even have to be
aware that s/he is using figurative speech, but informed speakers, if
asked, will be aware of the fact.
Davoud
--
usenet *at* davidillig dawt com
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Date: 14 Jul 2007 17:19:11
From: Brian Tung
Subject: Re: Definition of the sun's "death"?
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Chris L Peterson wrote:
> I would not consider them so. Certainly, the _original_ meaning of these
> terms is such that their first application to inanimate things should be
> considered figurative. But language evolves, and words come to have new
> meanings- meanings which cannot be considered figurative except in the
> most narrow sense of that word. They even become the basis of new words.
> Particles have "half-lives" and "lifetimes". Are these terms, which
> don't even have any synonyms in scientific usage, figurative, as well?
> Can a word be figurative if no literal alternative even exists?
Perhaps a better term would be "extended sense." Thus, we consider
people to be alive as long as they process fuel (air and food); on the
other hand, a person could be dead and still radiate warmth. In an
extended sense, we might well consider a star to be alive as long as
it processes fuel (hydrogen and later other, heavier elements). It
would cease to be alive in this sense as soon as fusion stops, although
it would of course continue to radiate heat.
--
Brian Tung <brian@isi.edu >
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
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Date: 14 Jul 2007 19:04:18
From: Davoud
Subject: Re: Definition of the sun's "death"?
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Davoud:
> >I was recently taken to task by such
> >a dolt in this forum for a humorous remark to the effect that some
> >amateurs image from 15,000-meter mountains in the Southwest! The idiot
> >thought that I believe that such mountains exist!
Chris L Peterson:
> I think you're being a bit harsh. Curtis hasn't demonstrated himself on
> this group to be a dolt.
Oops! I hope Curtis see this, or I hope he doesn't. Whatever. I know
that Mr. Croulet is no dolt. I wasn't referring to him; he replied
"15,000 meters???!!!" and the six punctuation marks told me that he had
not taken me seriously.
Davoud
--
usenet *at* davidillig dawt com
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Date: 13 Jul 2007 10:24:17
From: Double-A
Subject: Re: Definition of the sun's "death"?
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On Jul 13, 7:43 am, Chris L Peterson <c...@alumni.caltech.edu > wrote:
> On Fri, 13 Jul 2007 07:34:50 -0700, Double-A <double...@hush.ai> wrote:
>
> >Why do we insist on using such anthropomorphic terminology anyway?
> >Objects in space don't get born, live, and then die, they transition
> >from one kind of object into another. When we apply the terms of
> >carbon based life forms to inanimate objects, we are being completely
> >arbitrary. Otherwise, when a super massive star collapses, why not
> >say, "A black hole is born!"?
>
> I've heard that last said many times.
>
> It is in our nature to anthropomorphize our environment. And in fact, it
> is perfectly reasonable (even from a scientific standpoint) to speak of
> the birth, life, and death of a star. Stars don't exist forever in
> either direction, even if their material does. I could argue that you
> were never born, but just transformed from a different kind of object
> <g>.
>
> _________________________________________________
>
> Chris L Peterson
> Cloudbait Observatoryhttp://www.cloudbait.com
And so I was, O enlightened one.
Double-A
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Date: 13 Jul 2007 16:55:54
From: Sam Wormley
Subject: Re: Definition of the sun's "death"?
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Radium wrote:
> Hi:
>
> I just don't understand why the expansion of the sun into a red giant
> would be classified as the sun's 'death'. As a red giant, the sun will
> very much be alive as it is today. It will burn helium instead of the
> hydrogen it burns today.
>
> My definition of the "death of the sun", is when the sun ceases its
> nuclear fusion. Fusion is what gives the sun its life.
>
Fusion (after the radiation pressure of gravitational collapse) keeps
the star inflated against gravity... eventually gravity wins!
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Date: 13 Jul 2007 17:06:41
From: Chris L Peterson
Subject: Re: Definition of the sun's "death"?
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On Fri, 13 Jul 2007 16:55:54 GMT, Sam Wormley <swormley1@mchsi.com >
wrote:
> Fusion (after the radiation pressure of gravitational collapse) keeps
> the star inflated against gravity... eventually gravity wins!
A fact that applies to people as well <g >.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 13 Jul 2007 10:38:07
From: Shawn
Subject: Re: Definition of the sun's "death"?
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Radium wrote:
> Hi:
>
> I just don't understand why the expansion of the sun into a red giant
> would be classified as the sun's 'death'. As a red giant, the sun will
> very much be alive as it is today. It will burn helium instead of the
> hydrogen it burns today.
I like "senescence". Big word, sounds good ;-)
> My definition of the "death of the sun", is when the sun ceases its
> nuclear fusion. Fusion is what gives the sun its life.
Qualified in that "life of a star" sense, as opposed to biological life,
I agree.
Shawn
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Date: 13 Jul 2007 07:34:50
From: Double-A
Subject: Re: Definition of the sun's "death"?
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On Jul 13, 6:09 am, "N:dlzc D:aol T:com \(dlzc\)" <d...@aol.com >
wrote:
> Dear tony_flanders:
>
> <tony_fland...@yahoo.com> wrote in message
>
> news:1184331265.571374.137330@n60g2000hse.googlegroups.com...
>
> > On Jul 13, 12:33 am, Radium <gluceg...@gmail.com> wrote:
>
> >> I just don't understand why the expansion of the sun
> >> into a red giant would be classified as the sun's 'death'.
> >> ...
> >> My definition of the "death of the sun", is when the sun
> >> ceases its nuclear fusion.
>
> > I agree; it's sloppy terminology. A better term might be
> > death throes. But even that I'd save for the truly
> > terminal phase when the Sun creates a planetary
> > nebula. The red-giant phase would better be called
> > old age.
>
> How about "menopausal"? ;>)
>
> > Of course, stars continue to shine quite nicely even
> > after nuclear fusion has stopped. I would call a
> > white dwarf moribund rather than dead.
>
> David A. Smith
Why do we insist on using such anthropomorphic terminology anyway?
Objects in space don't get born, live, and then die, they transition
from one kind of object into another. When we apply the terms of
carbon based life forms to inanimate objects, we are being completely
arbitrary. Otherwise, when a super massive star collapses, why not
say, "A black hole is born!"?
Double-A
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Date: 13 Jul 2007 18:46:51
From: Androcles
Subject: Re: Definition of the sun's "death"?
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"Double-A" <double-aa@hush.ai > wrote in message
news:1184337290.253768.63600@i13g2000prf.googlegroups.com...
: On Jul 13, 6:09 am, "N:dlzc D:aol T:com \(dlzc\)" <d...@aol.com >
: wrote:
: > Dear tony_flanders:
: >
: > <tony_fland...@yahoo.com> wrote in message
: >
: > news:1184331265.571374.137330@n60g2000hse.googlegroups.com...
: >
: > > On Jul 13, 12:33 am, Radium <gluceg...@gmail.com> wrote:
: >
: > >> I just don't understand why the expansion of the sun
: > >> into a red giant would be classified as the sun's 'death'.
: > >> ...
: > >> My definition of the "death of the sun", is when the sun
: > >> ceases its nuclear fusion.
: >
: > > I agree; it's sloppy terminology. A better term might be
: > > death throes. But even that I'd save for the truly
: > > terminal phase when the Sun creates a planetary
: > > nebula. The red-giant phase would better be called
: > > old age.
: >
: > How about "menopausal"? ;>)
: >
: > > Of course, stars continue to shine quite nicely even
: > > after nuclear fusion has stopped. I would call a
: > > white dwarf moribund rather than dead.
: >
: > David A. Smith
:
: Why do we insist on using such anthropomorphic terminology anyway?
: Objects in space don't get born, live, and then die, they transition
: from one kind of object into another. When we apply the terms of
: carbon based life forms to inanimate objects, we are being completely
: arbitrary. Otherwise, when a super massive star collapses, why not
: say, "A black hole is born!"?
Black hole... a snake swallowing its own tail.
Possibly a neutron body... the nuclei, protons and electrons
compressed under gravity at the core; but at the surface, cold
evaporation to leave huge clouds of hydrogen light years across
and talking billions of years to form,
http://antwrp.gsfc.nasa.gov/apod/ap070106.html
which slowly absorb radiation from other stars before condensing
again to complete the cycle, the conclusion being a universe that always
was and always will be.
The core? Planets such as the Earth would fit the description
rather well with its abundance of heavy elements.
"Beginning" and "ending" are also anthropomorphisms, yet life itself
is cyclic, energy driven, so why should not the universe be so as well?
Big Bangs and black holes are rather silly theories, that's all.
If there were a big bang there'd be a detectable point from which
everything radiated, yet even the CMBR is homogeneous.
http://antwrp.gsfc.nasa.gov/apod/ap061007.html
And then there is this:
http://antwrp.gsfc.nasa.gov/apod/ap061008.html
The evidence for either wild conjecture simply isn't there, we
must examine the universe from ALL the data before we can
call ourselves scientists.
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Date: 13 Jul 2007 14:11:01
From: Dave Deming
Subject: Re: Definition of the sun's "death"?
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Theory states the "Big Bang" was the expansion of a point source
into what we view as the universe. Theory also states it happened
everywhere we look. Simple explanation is we are part and parcel of this
perspective
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Date: 13 Jul 2007 14:14:36
From: Dave Deming
Subject: Re: Definition of the sun's "death"?
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OOPS!! sent that incomplete. Our only possible perspective is
inside, looking out.
Dave
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Date: 13 Jul 2007 14:43:14
From: Chris L Peterson
Subject: Re: Definition of the sun's "death"?
|
On Fri, 13 Jul 2007 07:34:50 -0700, Double-A <double-aa@hush.ai > wrote:
>
>Why do we insist on using such anthropomorphic terminology anyway?
>Objects in space don't get born, live, and then die, they transition
>from one kind of object into another. When we apply the terms of
>carbon based life forms to inanimate objects, we are being completely
>arbitrary. Otherwise, when a super massive star collapses, why not
>say, "A black hole is born!"?
I've heard that last said many times.
It is in our nature to anthropomorphize our environment. And in fact, it
is perfectly reasonable (even from a scientific standpoint) to speak of
the birth, life, and death of a star. Stars don't exist forever in
either direction, even if their material does. I could argue that you
were never born, but just transformed from a different kind of object
<g >.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 13 Jul 2007 05:54:25
From:
Subject: Re: Definition of the sun's "death"?
|
On Jul 13, 12:33 am, Radium <gluceg...@gmail.com > wrote:
> I just don't understand why the expansion of the sun
> into a red giant would be classified as the sun's 'death'.
> ...
> My definition of the "death of the sun", is when the sun
> ceases its nuclear fusion.
I agree; it's sloppy terminology. A better term might be
death throes. But even that I'd save for the truly
terminal phase when the Sun creates a planetary
nebula. The red-giant phase would better be called
old age.
Of course, stars continue to shine quite nicely even
after nuclear fusion has stopped. I would call a
white dwarf moribund rather than dead.
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Date: 13 Jul 2007 06:09:11
From: N:dlzc D:aol T:com \(dlzc\)
Subject: Re: Definition of the sun's "death"?
|
Dear tony_flanders:
<tony_flanders@yahoo.com > wrote in message
news:1184331265.571374.137330@n60g2000hse.googlegroups.com...
> On Jul 13, 12:33 am, Radium <gluceg...@gmail.com> wrote:
>
>> I just don't understand why the expansion of the sun
>> into a red giant would be classified as the sun's 'death'.
>> ...
>> My definition of the "death of the sun", is when the sun
>> ceases its nuclear fusion.
>
> I agree; it's sloppy terminology. A better term might be
> death throes. But even that I'd save for the truly
> terminal phase when the Sun creates a planetary
> nebula. The red-giant phase would better be called
> old age.
How about "menopausal"? ; >)
> Of course, stars continue to shine quite nicely even
> after nuclear fusion has stopped. I would call a
> white dwarf moribund rather than dead.
David A. Smith
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Date: 13 Jul 2007 04:55:07
From: Sam Wormley
Subject: Re: Definition of the sun's "death"?
|
Radium wrote:
> Hi:
>
> I just don't understand why the expansion of the sun into a red giant
> would be classified as the sun's 'death'. As a red giant, the sun will
> very much be alive as it is today. It will burn helium instead of the
> hydrogen it burns today.
>
> My definition of the "death of the sun", is when the sun ceases its
> nuclear fusion. Fusion is what gives the sun its life.
>
>
> Best,
>
> Radium
>
Stars spend the majority of their "lives" on the main sequence, i.e.,
fusing hydrogen into helium. and the secondary, tertiary, etc. fusion
processes are short lived by comparison.
Star are born and stars die... just like us. The big massive stars have
but short lives, a few millions of years. Stars like our sun last for a
good 10 billions of years, and the little red stars like Barnard's Star
might last for 100 billion years. How long stars live, is determined by
their mass (which must be at least 80 Jupiter masses to sustain
thermonuclear fusion of hydrogen).
There are four (4) fates for the end of stars depending on their masses
and the masses of their cores:
Red/Brown Dwarfs - less than 0.6 Ms <== Main Sequence 0.076-0.8 Ms
Stars less than about 0.6 solar masses, when nuclear fuel is used up,
gravitational collapse shrinks the star, but no more than the gas
temperature-pressure-volume laws of classical physics allow. We have
not found any white dwarf less massive than 0.6 solar masses. Part of
the answer is that the universe may not be old enough for lower mass
stars to have evolved off the main sequence.
White Dwarfs - 0.6 and 1.44 Ms <== Main Sequence 0.8-8 Ms
Stars with core masses between 0.6 and 1.44 solar masses are
destined to become white dwarfs. White dwarfs are degenerate matter.
Further collapse is halted by electron degeneracy pressure. See pages
456-459 in your textbook. The vast majority of stars are in this mass
range and are destined to become white dwarfs
Neutron Stars - 1.44 and 2.9 Ms <== Main Sequence 8-30 Ms
Core masses between 1.44 and 2.9 solar masses overcome electron
degeneracy pressure and collapse to form neutron stars, a star that is
essentially one gigantic nucleus. Further collapse is halted by neutron
degeneracy pressure.
Black Holes - 3 or more Ms <== Main Sequence > 30 Ms
But for cores with mass of 3 or more solar masses, neutron
degeneracy pressure does not stop the collapse and the star becomes a
black hole with zero physical size, but with all the mass. Gravity
really wins!
In each case, gravity eventually wins, but, to what extent is
determined by the mass and the relative pressures of the quantum
mechanical forces, electron and neutron degeneracy pressure. Your book
has an excellent diagram on page 459 relating the original star mass to
that of the final core mass (core mass being the mass of whats left of
the star at the end of its evolutionary processes).
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Date: 16 Jul 2007 20:05:27
From: Stuart Chapman
Subject: Re: Definition of the sun's "death"?
|
Sam Wormley wrote:
> Radium wrote:
>> Hi:
>>
>> I just don't understand why the expansion of the sun into a red giant
>> would be classified as the sun's 'death'. As a red giant, the sun will
>> very much be alive as it is today. It will burn helium instead of the
>> hydrogen it burns today.
>>
>> My definition of the "death of the sun", is when the sun ceases its
>> nuclear fusion. Fusion is what gives the sun its life.
>>
>>
>> Best,
>>
>> Radium
>>
>
> Stars spend the majority of their "lives" on the main sequence, i.e.,
> fusing hydrogen into helium. and the secondary, tertiary, etc. fusion
> processes are short lived by comparison.
>
> Star are born and stars die... just like us. The big massive stars have
> but short lives, a few millions of years. Stars like our sun last for a
> good 10 billions of years, and the little red stars like Barnard's Star
> might last for 100 billion years. How long stars live, is determined by
> their mass (which must be at least 80 Jupiter masses to sustain
> thermonuclear fusion of hydrogen).
>
> There are four (4) fates for the end of stars depending on their masses
> and the masses of their cores:
>
> Red/Brown Dwarfs - less than 0.6 Ms <== Main Sequence 0.076-0.8 Ms
> Stars less than about 0.6 solar masses, when nuclear fuel is used up,
> gravitational collapse shrinks the star, but no more than the gas
> temperature-pressure-volume laws of classical physics allow. We have
> not found any white dwarf less massive than 0.6 solar masses. Part of
> the answer is that the universe may not be old enough for lower mass
> stars to have evolved off the main sequence.
>
> White Dwarfs - 0.6 and 1.44 Ms <== Main Sequence 0.8-8 Ms
> Stars with core masses between 0.6 and 1.44 solar masses are
> destined to become white dwarfs. White dwarfs are degenerate matter.
> Further collapse is halted by electron degeneracy pressure. See pages
> 456-459 in your textbook. The vast majority of stars are in this mass
> range and are destined to become white dwarfs
>
> Neutron Stars - 1.44 and 2.9 Ms <== Main Sequence 8-30 Ms
> Core masses between 1.44 and 2.9 solar masses overcome electron
> degeneracy pressure and collapse to form neutron stars, a star that is
> essentially one gigantic nucleus. Further collapse is halted by neutron
> degeneracy pressure.
>
> Black Holes - 3 or more Ms <== Main Sequence > 30 Ms
> But for cores with mass of 3 or more solar masses, neutron
> degeneracy pressure does not stop the collapse and the star becomes a
> black hole with zero physical size, but with all the mass. Gravity
> really wins!
>
> In each case, gravity eventually wins, but, to what extent is
> determined by the mass and the relative pressures of the quantum
> mechanical forces, electron and neutron degeneracy pressure. Your book
> has an excellent diagram on page 459 relating the original star mass to
> that of the final core mass (core mass being the mass of whats left of
> the star at the end of its evolutionary processes).
Something I'd like to know:
Just what will be left of a star (that won't explode into a neutron star
or black hole) some 20 billion years from now. A cold, spinning sphere
of iron that you could walk on?
All stellar 'histories' that I have read (maybe I should say
understood), don't seem to elaborate on this.
As for the neutron star: Has there been any speculation as to how this
would appear if you could orbit one from a safe distance?
--
Stupot http://insignity.blogspot.com
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Date: 16 Jul 2007 16:06:14
From: Norbert
Subject: Re: Definition of the sun's "death"?
|
Stuart Chapman nous a donc écrit :
> Something I'd like to know:
>
> Just what will be left of a star (that won't explode into a neutron
> star or black hole) some 20 billion years from now. A cold, spinning
> sphere of iron that you could walk on?
Not iron. Degenerate electronic matter is the constituent of a white dwarf.
Don't ask me the aspect of this matter :)
You could obviously walk on it, if you are not crushed by gravitation.
And in 20 billion years, this sphere of matter will surely be as cold as the
rest of the universe.
>
> All stellar 'histories' that I have read (maybe I should say
> understood), don't seem to elaborate on this.
>
> As for the neutron star: Has there been any speculation as to how this
> would appear if you could orbit one from a safe distance?
You could refer to this page
http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html where you will find some
animation films about travelling to a neutron star.
The aspect of a neutron star must be a (quite) perfect sphere of iron, which
forms the crust of the star.
--
Norbert. (no X for the answer)
======================================
knowing the universe - stellar and galaxies evolution
http://nrumiano.free.fr
images of the sky http://images.ciel.free.fr
======================================
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Date: 16 Jul 2007 14:13:41
From: Chris L Peterson
Subject: Re: Definition of the sun's "death"?
|
On Mon, 16 Jul 2007 16:06:14 +0200, "Norbert"
<Xnorbert.rumiano@numericable.frX > wrote:
>Not iron. Degenerate electronic matter is the constituent of a white dwarf.
>Don't ask me the aspect of this matter :)
>You could obviously walk on it, if you are not crushed by gravitation.
>And in 20 billion years, this sphere of matter will surely be as cold as the
>rest of the universe.
I think that in just 20 billion years, you'd still get toasted pretty
well walking on the surface of a neutron star. It would still be a few
thousand degrees. Better give it at least a few hundred billion years if
you want it cool enough to walk on.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 16 Jul 2007 17:11:52
From: Norbert
Subject: Re: Definition of the sun's "death"?
|
Chris L Peterson nous a donc écrit :
> On Mon, 16 Jul 2007 16:06:14 +0200, "Norbert"
> <Xnorbert.rumiano@numericable.frX> wrote:
>
>> Not iron. Degenerate electronic matter is the constituent of a white
>> dwarf. Don't ask me the aspect of this matter :)
>> You could obviously walk on it, if you are not crushed by
>> gravitation.
>> And in 20 billion years, this sphere of matter will surely be as
>> cold as the rest of the universe.
>
> I think that in just 20 billion years, you'd still get toasted pretty
> well walking on the surface of a neutron star. It would still be a few
> thousand degrees. Better give it at least a few hundred billion years
> if you want it cool enough to walk on.
>
I was talking about white dwarf. And from
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v486n1/34903/34903.html?erFrom=2172745545864961312Guest
it seems that about 10 billion years will be enough.
Of course, for a neutron star, it will take a much much longer time :)
--
Norbert. (no X for the answer)
======================================
knowing the universe - stellar and galaxies evolution
http://nrumiano.free.fr
images of the sky http://images.ciel.free.fr
======================================
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Date: 16 Jul 2007 15:50:51
From: Chris L Peterson
Subject: Re: Definition of the sun's "death"?
|
On Mon, 16 Jul 2007 17:11:52 +0200, "Norbert"
<Xnorbert.rumiano@numericable.frX > wrote:
>I was talking about white dwarf. And from
>http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v486n1/34903/34903.html?erFrom=2172745545864961312Guest
>it seems that about 10 billion years will be enough.
Sorry, I was thinking white dwarf even while typing neutron star. And
from my reading of the referenced paper, a typical white dwarf
temperature will be about 15,000 K after 10 billion years... a little
warmer than I'd care to walk on! That temperature is also in line with
what you get modeling the luminosity function as a simple exponential
(which was the source of my time estimates elsewhere in this
discussion).
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 16 Jul 2007 23:19:18
From: Norbert
Subject: Re: Definition of the sun's "death"?
|
Chris L Peterson nous a donc écrit :
> On Mon, 16 Jul 2007 17:11:52 +0200, "Norbert"
> <Xnorbert.rumiano@numericable.frX> wrote:
>
>> I was talking about white dwarf. And from
>> http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v486n1/34903/34903.html?erFrom=2172745545864961312Guest
>> it seems that about 10 billion years will be enough.
>
> Sorry, I was thinking white dwarf even while typing neutron star. And
> from my reading of the referenced paper, a typical white dwarf
> temperature will be about 15,000 K after 10 billion years... a little
> warmer than I'd care to walk on! That temperature is also in line with
> what you get modeling the luminosity function as a simple exponential
> (which was the source of my time estimates elsewhere in this
> discussion).
>
Chris, you're right. My first reading of this article was a bit too fast.
I agree : I won't put my feet on such a star :)
--
Norbert. (no X for the answer)
======================================
knowing the universe - stellar and galaxies evolution
http://nrumiano.free.fr
images of the sky http://images.ciel.free.fr
======================================
|
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Date: 16 Jul 2007 13:57:41
From: Sam Wormley
Subject: Re: Definition of the sun's "death"?
|
Stuart Chapman wrote:
>
> Something I'd like to know:
>
> Just what will be left of a star (that won't explode into a neutron star
> or black hole) some 20 billion years from now. A cold, spinning sphere
> of iron that you could walk on?
>
> All stellar 'histories' that I have read (maybe I should say
> understood), don't seem to elaborate on this.
>
> As for the neutron star: Has there been any speculation as to how this
> would appear if you could orbit one from a safe distance?
>
When there is no further energy source to hold up a star the star will
become degenerate with total mass greater than about 0.6 solar masses.
And of course there is a limit--the Chandrasekhar limit of 1.44 solar
masses. The remnant will most likely have a gas surface for a very long
time, however trillions of years into the future it should "freeze"
solid. As for walking on it... the gravitation would be enormous.
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Date: 14 Jul 2007 09:08:08
From: Odysseus
Subject: Re: Definition of the sun's "death"?
|
In article <LADli.26938$Fc.8903@attbi_s21 >,
Sam Wormley <swormley1@mchsi.com > wrote:
<snip >
> Your book has an excellent diagram on page 459 relating the original
> star mass to that of the final core mass (core mass being the mass of
> whats left of the star at the end of its evolutionary processes).
What book is that? I assume your posting was taken from class notes --
what course?
--
Odysseus
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Date: 14 Jul 2007 15:32:42
From: Sam Wormley
Subject: Re: Definition of the sun's "death"?
|
Odysseus wrote:
> In article <LADli.26938$Fc.8903@attbi_s21>,
> Sam Wormley <swormley1@mchsi.com> wrote:
>
> <snip>
>
>> Your book has an excellent diagram on page 459 relating the original
>> star mass to that of the final core mass (core mass being the mass of
>> whats left of the star at the end of its evolutionary processes).
>
> What book is that? I assume your posting was taken from class notes --
> what course?
>
I've been teaching from "Astronomy: Journey To The Cosmic Frontier", 4th ed
by John D. Fix ISBN: 007299181x
http://www.mhhe.com/fix/
Syllabus
http://edu-observatory.org/mcc/syllabus
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Date: 14 Jul 2007 09:45:38
From: Tom Kerr
Subject: Re: Definition of the sun's "death"?
|
In article <odysseus1479-at-3033AE.03080814072007@news.telus.net >, Odysseus <odysseus1479-at@yahoo-dot.ca> wrote:
>In article <LADli.26938$Fc.8903@attbi_s21>,
> Sam Wormley <swormley1@mchsi.com> wrote:
>
><snip>
>
>> Your book has an excellent diagram on page 459 relating the original
>> star mass to that of the final core mass (core mass being the mass of
>> whats left of the star at the end of its evolutionary processes).
>
>What book is that? I assume your posting was taken from class notes --
>what course?
Google can be so useful sometimes. It's a direct quote from:
http://edu-observatory.org/mcc/homework/homework.ch.18-19/homework.ch.
18-19.html
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Date: 14 Jul 2007 09:35:17
From: Tom Kerr
Subject: Re: Definition of the sun's "death"?
|
In article <odysseus1479-at-3033AE.03080814072007@news.telus.net >, Odysseus <odysseus1479-at@yahoo-dot.ca> wrote:
>In article <LADli.26938$Fc.8903@attbi_s21>,
> Sam Wormley <swormley1@mchsi.com> wrote:
>
><snip>
>
>> Your book has an excellent diagram on page 459 relating the original
>> star mass to that of the final core mass (core mass being the mass of
>> whats left of the star at the end of its evolutionary processes).
>
>What book is that? I assume your posting was taken from class notes --
>what course?
Glad I wasn't the only one wondering about this. I looked at the thread
and other possibly related threads and couldn't work out what the
reference to "your book" was all about. I'd like to find out as well.
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