[meteorite-list] Death Star Story - Link corrected

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu, 7 Jan 2010 12:44:36 -0600
Message-ID: <CC67EA40B29242A28C41CF44938DDEEA_at_ATARIENGINE2>

Count, Carl, Larry, and List,

I notice that a number of "respected" sources,
like Scientific American's website and Astronomy
magazine's jumped on this story without looking
at what they were landing in. And because they
did that, a number odf science blogs did the same.
Now everybody has a little back-pedalling to do.

Not that a nova or a supernova wouldn't make life
very interesting here on Earth... What are the
cataclysmic variable candidates nearby?

The nearest supernova candidate is IK Pegasi
(HR 8210), located at a distance of 150 light-years.
This closely orbiting binary star system consists
of a main sequence star and a white dwarf,
separated by 31 million kilometres. The dwarf
has an estimated mass equal to 1.15 times that
of the Sun. It is thought that several million years
will pass before the white dwarf can accrete the
critical mass required to become a violent Type Ia
supernova.

The Chandrasekhar Limit, mentioned in several
of these news stories, but never defined, is about
1.4 times the mass of our Sun. Stars like ours end
up as white dwarves at the end of their life. Dense
white dwarf matter is created when all the atoms
of the star are squeezed so hard the nuclei are no
longer bound to their own electrons and the nuclei
all just swim in a random sea of squeezed electrons.
They call this "degenerate" matter.

Gravity does the squeezing, so white dwarf matter is
very dense. George Gamov used the comparison that
a matchbox full of white dwarf matter weighed as much
as a very large bull elephant. Heavy stuff.

If you keep piling mater onto a white dwarf, it eventually
gets so heavy that the electrons start to be squeezed back
into the nuclei, turning the protons in the nuclei into
more neutrons. Before you know it, there are no atoms,
just a sea of neutrons, and you have a neutron star.

But it's a violent and messy process.

If you add matter in dribbles, you have a cataclysmic
variable. Dump all the matter on at once, you have a
runaway process that ends in a supernova. But whether
you increase the mass slowly or rapidly, once you reach
the Chandrasekhar Limit of mass, there's no stopping it.

Most neutron stars are produced directly by supernova
from stars that started out weighing more 1.4 (but less
than 3.0) solar masses. It was all over in a single bad
supernova instant for them. Because these cataclysmic
variables are binaries of a white dwarf with a larger star,
and a close binary at that, they are very rare, yes, freaks,
tippitoeing up to disaster, flirting with the big moment.
No wonder we find them so entertaining. It's like a dance
number.

The best bet for a supernova soon? The big red giant star
Betelgeuse in Orion, a bright and familiar star we've all
seen. It's 570 light years away (safe distance). It's 8.5 million
years old (old for its mass) and it's been shrinking for 15
consecutive years (start of the collapse?). Wow! That would
be a show-stopper!
http://en.wikipedia.org/wiki/Betelgeuse#Fate

But it probably won't happen for thousands of years...
unless I get lucky. I would love to see a supernova.
As always, from a distance...


Sterling K. Webb
------------------------------------------------------------------------------
----- Original Message -----
From: <countdeiro at earthlink.net>
To: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>;
<meteorite-list at meteoritecentral.com>
Sent: Thursday, January 07, 2010 11:15 AM
Subject: Re: [meteorite-list] Death Star Story - Link corrected


> Sterling and List,
>
> Your fully annotated response is one of the reasons I appreciate the
> List. Thank you for the reply. I can use it to calm down some friends.
> I had some concerns myself...not knowing "poop" about the lethality of
> supernovas and GRBs.
>
> Guido
>
> -----Original Message-----
>>From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
>>Sent: Jan 7, 2010 3:57 AM
>>To: countdeiro at earthlink.net, meteorite-list at meteoritecentral.com
>>Subject: Re: [meteorite-list] Death Star Story - Link corrected
>>
>>Dear Count, and Listoids,
>>
>>Another story:
>>http://www.popsci.com/technology/article/2010-01/star-verge-supernova-could-threaten-life-earth
>>
>>And another:
>>http://www.spacedaily.com/reports/T_Pyxidis_Soon_To_Be_A_Type_Ia_Supernova_999.html
>>
>>And another:
>>http://www.astronomy.com/asy/default.aspx?c=a&id=8944
>>
>>All taken from the same press release, you will note.
>>
>>And all equally in error about The End Of All Life As
>>We Know It. It's a math mistake: "However, Dr. Sion's
>>calculations were challenged by Prof. Alex Fillipenko
>>who said that Sion had possibly miscalculated the
>>damage that could be caused by a T Pyxidis supernova.
>>He had used data for a far more deadly gamma-ray burst
>>(GRB) exploding 3,260 light-years from Earth, not a
>>supernova, and T Pyxidis certainly isn't expected to
>>produce a GRB. According to an another expert,
>>"A supernova would have to be 10 times closer [to Earth]
>>to do the damage described."
>>http://en.wikipedia.org/wiki/T_Pyxidis
>>
>>Information about nearby supernovas of the recent past:
>>http://science.nasa.gov/headlines/y2003/06jan_bubble.htm
>>
>>The truth is a supernova would be disastrous at 25 light
>>years away (not 3260). 50 light years away and it would
>>cause some damage, although it's hard to say how much.
>>100 light years away and it would be the action movie of
>>all time but you might worry that you sat too near to the
>>screen. There are two kinds (strengths) of supernovas. For
>>the Big One, I'd want to sit further away than the 300 Light
>>Year Line
>>
>>But 3260 light years? Fergettabouttit!
>>
>>Now, I can go to bed without worrying about a darn
>>Supernova...
>>
>>It's always something.
>>
>>
>>Sterling K. Webb
>>--------------------------------------------------------------------------------------
>>----- Original Message -----
>>From: <countdeiro at earthlink.net>
>>To: <meteorite-list at meteoritecentral.com>
>>Sent: Thursday, January 07, 2010 1:18 AM
>>Subject: [meteorite-list] Death Star Story - Link corrected
>>
>>
>>>
>>> Sorry List,
>>> Here is corrected link re previous Death Star post.
>>> Count Deiro
>>>
>>> http://www.thesun.co.uk/sol/homepage/news/2795981/Supernova-may-wipe-out-the-Earth.html
>>> ______________________________________________
>>> http://www.meteoritecentral.com
>>> Meteorite-list mailing list
>>> Meteorite-list at meteoritecentral.com
>>> http://six.pairlist.net/mailman/listinfo/meteorite-list
>>
>
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Received on Thu 07 Jan 2010 01:44:36 PM PST