mass limit

hi, is there an actual name for the mass limit that a planet must achieve
beyond which it will collapse and become a star?

i studied astrophysics many years ago and seemed to remember there was, or
am I becoming confused with the chandraseka (spelling may be well off there)
limit for a black hole?

thanks

Are you talking about a Jupiter type planet or a rockry planet? Becuae the
rockry planet would never reach the point where it would become a star.

As far as a Jupiter type planet to reach even the level where it would
become a dim short lived R.D. star it would be somewhere around 25 jupiter
mass. To become a star like our own, it would never be a planet at all, it
would be a cloud of gas that would be compressed under it's own g force to
the point where the fushion reaction would start and thus a star is born.


--
The Lone Sidewalk Astronomer of Rosamond

Telescope Buyers FAQ
http://home.inreach.com/starlord
Sidewalk Astronomy
www.sidewalkastronomy.info
The Church of Eternity
http://home.inreach.com/starlord/church/Eternity.html


"Jeremy Watts" wrote in message
news
hi, is there an actual name for the mass limit that a planet must achieve
beyond which it will collapse and become a star?

i studied astrophysics many years ago and seemed to remember there was, or
am I becoming confused with the chandraseka (spelling may be well off
there)
limit for a black hole?

thanks

"Starlord" wrote in message
...
Are you talking about a Jupiter type planet or a rockry planet? Becuae the
rockry planet would never reach the point where it would become a star.

As far as a Jupiter type planet to reach even the level where it would
become a dim short lived R.D. star it would be somewhere around 25 jupiter
mass. To become a star like our own, it would never be a planet at all, it
would be a cloud of gas that would be compressed under it's own g force to
the point where the fushion reaction would start and thus a star is born.

yeah i may be getting confused here with the mass limit for a black hole,
but i just seemed to remember there was a name for a hypothetical mass limit
beyond which a star would be formed.



--
The Lone Sidewalk Astronomer of Rosamond

Telescope Buyers FAQ
http://home.inreach.com/starlord
Sidewalk Astronomy
www.sidewalkastronomy.info
The Church of Eternity
http://home.inreach.com/starlord/church/Eternity.html


"Jeremy Watts" wrote in message
news
hi, is there an actual name for the mass limit that a planet must
achieve
beyond which it will collapse and become a star?

i studied astrophysics many years ago and seemed to remember there was,
or
am I becoming confused with the chandraseka (spelling may be well off
there)
limit for a black hole?

thanks

One small note, there is NO limit for mass in a Black Hole. The one in the
center of our own galaxy is somewhere in the range up to something like
1,000 to 5,000 solar mass and the one in M31 is somewhere aroun 1 million
solar mass. They figure this out by watchng the stars that are in orbit
around the Black Hole and clock how fast they move.

I think sometime I might have read the name that you are thinking of, but I
didn't take a full note of it so I have forgotten it.


--
The Lone Sidewalk Astronomer of Rosamond

Telescope Buyers FAQ
http://home.inreach.com/starlord
Sidewalk Astronomy
www.sidewalkastronomy.info
The Church of Eternity
http://home.inreach.com/starlord/church/Eternity.html


"Jeremy Watts" wrote in message
...

"Starlord" wrote in message
...
Are you talking about a Jupiter type planet or a rockry planet? Becuae
the
rockry planet would never reach the point where it would become a star.

As far as a Jupiter type planet to reach even the level where it would
become a dim short lived R.D. star it would be somewhere around 25
jupiter
mass. To become a star like our own, it would never be a planet at all,
it
would be a cloud of gas that would be compressed under it's own g force
to
the point where the fushion reaction would start and thus a star is born.

yeah i may be getting confused here with the mass limit for a black hole,
but i just seemed to remember there was a name for a hypothetical mass
limit
beyond which a star would be formed.



--
The Lone Sidewalk Astronomer of Rosamond

Telescope Buyers FAQ
http://home.inreach.com/starlord
Sidewalk Astronomy
www.sidewalkastronomy.info
The Church of Eternity
http://home.inreach.com/starlord/church/Eternity.html


"Jeremy Watts" wrote in message
news
hi, is there an actual name for the mass limit that a planet must
achieve
beyond which it will collapse and become a star?

i studied astrophysics many years ago and seemed to remember there was,
or
am I becoming confused with the chandraseka (spelling may be well off
there)
limit for a black hole?

thanks

Starlord wrote:
One small note, there is NO limit for mass in a Black Hole.

The one in the
center of our own galaxy is somewhere in the range up to something like
1,000 to 5,000 solar mass

Sagittarius A*
"Later observations determined the mass of the object to be about 3.7
million solar masses (our sun's mass is approximately 2×10^30 kg).
http://en.wikipedia.org/wiki/Sagittarius_A%2A

At the Center of the Milky Way
"At the center of our Milky Way Galaxy lies a black hole with over 2
million times the mass of the Sun."
http://antwrp.gsfc.nasa.gov/apod/ap021018.html

The Structure of the Milky Way
"The evidence is mounting that Sag A* is indeed a black hole of 2-3
million times the mass of the sun."
http://cassfos02.ucsd.edu/public/tutorial/MW.html



and the one in M31 is somewhere aroun 1 million
solar mass.

Mysterious Stars Surround Andromeda's Black Hole
"It packs a mass of 140 million suns, the new study finds."
http://www.space.com/scienceastronom...eda_stars.html

Andromeda Galaxy
"Andromeda's core has a supermassive central black hole of around 140
million Solar-masses (latest NASA press release)."
http://www.solstation.com/x-objects/andromeda.htm



They figure this out by watchng the stars that are in orbit
around the Black Hole and clock how fast they move.

I think sometime I might have read the name that you are thinking of, but I
didn't take a full note of it so I have forgotten it.


--
The Lone Sidewalk Astronomer of Rosamond

Telescope Buyers FAQ
http://home.inreach.com/starlord
Sidewalk Astronomy
www.sidewalkastronomy.info
The Church of Eternity
http://home.inreach.com/starlord/church/Eternity.html

"Jeremy Watts" wrote...
in message news

hi, is there an actual name for the mass limit that a planet must achieve
beyond which it will collapse and become a star?

i studied astrophysics many years ago and seemed to remember there was, or
am I becoming confused with the chandraseka (spelling may be well off
there)
limit for a black hole?

thanks

'Lo Jeremy --

Here's info on the "Chandrasekhar limit"...

http://en.wikipedia.org/wiki/Chandra_Limit

....which has to do with white dwarf stars. And
here's another similar limit for neutron stars...

http://en.wikipedia.org/wiki/Tolman-...-Volkoff_limit

The mass limit between a planet and a star has
no name at the moment that i can find. This may
be due to the limit being very blurred right now.

There is something called a "brown dwarf" that
falls on the scale sort of in-between a star and a
planet. The limit here is about 75 Jupiter masses
(75 times the mass of planet Jupiter).

So unless a star has at least 75 Jupiter masses
(with a metallicity similar to our Sun's) it would
be considered a "failed star", a brown dwarf...

http://en.wikipedia.org/wiki/Star#Mass

This holds down to about 13 Jupiter masses. At
this point the orb is called a "sub-brown dwarf".
These have been found with masses as low as
Saturn's, so as i said, the boundary between a
planet and a sub-brown dwarf is poorly defined.
Some scientists see no distinction between sub-
brown dwarfs and gas-giant planets.

Here is more detail which leads me to suspect
that perhaps someday, when better defined, this
limit may come to be known as the "Boss limit",
after Alan Boss...

http://www.carnegieinstitution.org/News4-3,2001.html

happy days and...
starry starry nights!

--
Indelibly yours,
Paine
http://www.painellsworth.net
http://www.savethechildren.org

Jeremy Watts wrote:
"Starlord" wrote in message
...
Are you talking about a Jupiter type planet or a rockry planet? Becuae the
rockry planet would never reach the point where it would become a star.

As far as a Jupiter type planet to reach even the level where it would
become a dim short lived R.D. star it would be somewhere around 25 jupiter
mass. To become a star like our own, it would never be a planet at all, it
would be a cloud of gas that would be compressed under it's own g force to
the point where the fushion reaction would start and thus a star is born.

yeah i may be getting confused here with the mass limit for a black hole,
but i just seemed to remember there was a name for a hypothetical mass limit
beyond which a star would be formed.


The current IAU position on the borderline between 'planet' and 'brown
dwarf star' is around 13 Jupiter masses (or 2.4687*10^28kg) for bodies
with metalicity like our sun.

IIRC anything under about 0.1 solar masses (or 1.981*10^29kg) can't fuse
hydrogen, and only burns isotopes like Deuterium, and that is considered
the upper range of 'brown dwarf' starts and the bottom range of 'red
dwarf' stars.

So the approximate ranges a 13 jovian masses is a planet, 13 - 100
jovian masses is a brown dwarf star, and somewhere over 100 jovian
masses (0.1 solar masses) it begins burning hydrogen and is a red dwarf
star.

The mass of the Sun is 1.9891*10^30kg, and the mass of Jupiter is
1.899*10^27kg, so the sun is about 1,047 jovian masses.


[snip]

--
Bill Hudson

Painius As you know my mass limit for a BH is 6 trillion stars. At that
point it will implode. Best to keep in mind the compression force of
gravity creates implode,and implode creates explode. Bert

G=EMC^2 Glazier wrote:
Painius As you know my mass limit for a BH is 6 trillion stars.


Which I'm sure you arrived at precisely after years of studying reams
of data and suitably applying calculations involving tensor calculus.



At that
point it will implode. Best to keep in mind the compression force of
gravity creates implode,and implode creates explode. Bert


Hmmm! Sort of like when you put a bullet through the picture tube of
your old TV set.

Double-A

Double-A TV picture tube sends the glass globe in to explode out. Even
the trigger of an H-Bomb fits Bert