# Largest known planet found



## Allegra (Aug 7, 2007)

BBC NEWS | Science/Nature | Team finds largest exoplanet yet

"*An international team of astronomers has discovered the largest known planet orbiting another star.* 

The "transiting" planet - meaning one that passes in front of its parent star as seen from Earth - is about 70% larger than Jupiter. But the presumed "gas giant" has a much lower mass than Jupiter - the biggest planet in our Solar System - making it of extremely low density."


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## The Ace (Aug 7, 2007)

Maybe it has a few friends.


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## Curt Chiarelli (Aug 8, 2007)

Fascinating stuff . . . . I'm curious to know whether this gas giant is another "failed sun" like our own Jupiter. Depending on a lot of mitigating factors, it could have turned into a binary star system! 

Once again, proof positive that if one needs to experience an overpowering sense of awe and wonder one need not seek out supernatural phenomena - the natural world is more than up to the task!


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## Spartan27 (Aug 24, 2007)

Curt Chiarelli said:


> Fascinating stuff . . . . I'm curious to know whether this gas giant is another "failed sun" like our own Jupiter. Depending on a lot of mitigating factors, it could have turned into a binary star system!
> 
> Once again, proof positive that if one needs to experience an overpowering sense of awe and wonder one need not seek out supernatural phenomena - the natural world is more than up to the task!


 

How do you know our Jupiter is a failed sun? Your assuming a lot there Curt.


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## Nik (Aug 24, 2007)

IIRC, Jupiter is still not big enough to go 'Brown Dwarf' even if you add Saturn, Uranus, Neptune and the known Oort objects...

Also, IIRC, if you look at the radius / mass spectrum of gas-giants <~~> Brown Dwarfs <~~> Red Dwarfs, there's a zig-zag. If you keep adding material to a Jupiter sized jovian, it gets bigger and bigger until gravity crushes the core beyond 'metallic hydrogen' to dense plasma hot enough to fuse lithium. For a time, adding more mass makes the core bigger but overall object *smaller*. That, IMHO, is when you cross the line from planet to failed star. After that kink, the object again grows in size with added mass until you have a recognisable star...

So, you may have Brown Dwarf 'failed stars' that are more massive but significantly smaller than big gas giants...

IIRC, gotta look for legacy lithium etc in the spectrum... and use Newton's Laws to back-calculate from orbit to mass.


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## Spartan27 (Aug 27, 2007)

Nik said:


> IIRC, Jupiter is still not big enough to go 'Brown Dwarf' even if you add Saturn, Uranus, Neptune and the known Oort objects...
> 
> Also, IIRC, if you look at the radius / mass spectrum of gas-giants <~~> Brown Dwarfs <~~> Red Dwarfs, there's a zig-zag. If you keep adding material to a Jupiter sized jovian, it gets bigger and bigger until gravity crushes the core beyond 'metallic hydrogen' to dense plasma hot enough to fuse lithium. For a time, adding more mass makes the core bigger but overall object *smaller*. That, IMHO, is when you cross the line from planet to failed star. After that kink, the object again grows in size with added mass until you have a recognisable star...
> 
> ...


 
Nice, and exactly....


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## Curt Chiarelli (Aug 28, 2007)

Spartan27 said:


> How do you know our Jupiter is a failed sun? Your assuming a lot there Curt.



No assumptions, only scientific theory and, in this case, it's one that's been bandied about by leading astronomers.


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## Nik (Aug 28, 2007)

*Assuming same formation route...*

In the sense that we have a jovian and a G-type star instead of a binary pair of M-types, yes, Jupiter is a failed star.

Once upon a time, before *any* extra-solar planets were known, designing a solar system for SciFi was so easy...

Choose the star's colour and Giant / MainSequence. That gave the mass and temperature. They set the 'snow-line', where the system's 'Jupiter' grew and lived. That set the system resonances, defined where 'terrestial' planets could orbit. If these did not fall into 'temperate' zone, then you gotta choose another star or tweak the plot...

Oh, and don't forget that Sol-type stars warm up a bit as the aeons pass...

The discovery of 'hot close' jovians changed all that. The realisation grew that these may not have formed in close orbit, may have migrated, may have swatted 'terrestial' planets like so many soft-balls...

This suggests there are *at least* two ways to make a Jovian. One may be the 'snow-line' recipe, meaning it grew as a planet. Happens our Jupiter seems to have stayed fairly near the snow-line...

Another recipe may be 'binary runt', at the end of a spectrum that runs from 1:1 down to red and brown dwarf stars / sub-stars...

The universe being stranger than we can imagine, there's probably 'Some of A plus some of B' jovians, 'capture' routes for stray planets, and mega-accretions, like the one which surely tipped Uranus...

If your math works, there's surely some jovians like it out there. IMHO, there's a zoo.


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## Spartan27 (Aug 30, 2007)

*Re: Assuming same formation route...*



Nik said:


> In the sense that we have a jovian and a G-type star instead of a binary pair of M-types, yes, Jupiter is a failed star.
> 
> Once upon a time, before *any* extra-solar planets were known, designing a solar system for SciFi was so easy...
> 
> ...


 
"Snow-line" is what I was talking about....in my past post. The theory is still a bit "loose" though.


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## Nik (Aug 30, 2007)

*Migrating jovians...*

I'm sorry, I don't have the math or access to the research to go further...

All I know is that there must be at least two distinct recipes for sub-jovians, jovians and super-jovians, and Jupiter seems to be 'Snow-Line' rather than 'Sub-Star'.

Perhaps some quirk of the zoo's spectra will hold the key ??

IIRC, Jovians may shift orbit by gravity-slinging the planetismals they don't swallow, and building orbital resonances with neighbours.


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## Nik (Sep 1, 2007)

*Want ice in that ??*

Press Release: Water Vapor Seen 'Raining Down' on Young Star System

excerpt #1:

NASA's Spitzer Space Telescope has detected enough water vapor to fill the oceans on Earth five times inside the collapsing nest of a forming star system. Astronomers say the water vapor is pouring down from the system's natal cloud and smacking into a dusty disk where planets are thought to form. 

The observations provide the first direct look at how water, an essential ingredient for life as we know it, begins to make its way into planets, possibly even rocky ones like our own. 

"For the first time, we are seeing water being delivered to the region where planets will most likely form," said Dan Watson of the University of Rochester, N.Y. Watson is the lead author of a paper about this "steamy" young star system, appearing in the Aug. 30 issue of Nature. 

The star system, called NGC 1333-IRAS 4B, is still growing inside a cool cocoon of gas and dust. Within this cocoon, circling around the embryonic star, is a burgeoning, warm disk of planet-forming materials. The new Spitzer data indicate that ice from the stellar embryo's outer cocoon is falling toward the forming star and vaporizing as it hits the disk. 

"On Earth, water arrived in the form of icy asteroids and comets. Water also exists mostly as ice in the dense clouds that form stars," said Watson. "Now we've seen that water, falling as ice from a young star system's envelope to its disk, actually vaporizes on arrival. This water vapor will later freeze again into asteroids and comets." 

excerpt #2

Watson and his colleagues studied 30 of the youngest known stellar embryos using Spitzer's infrared spectrograph, an instrument that splits infrared light open into a rainbow of wavelengths, revealing "fingerprints" of molecules. Of the 30 stellar embryos, they found only one, NGC 1333-IRAS 4B, with a whopping signature of water vapor. This vapor is readily detectable by Spitzer, because as ice hits the stellar embryo's planet-forming disk, it heats up very rapidly and glows with infrared light. 

Why did only one stellar embryo of 30 show signs of water? The astronomers say this is most likely because NGC 1333-IRAS 4B is in just the right orientation for Spitzer to view its dense core. Also, this particular watery phase of a star's life is short-lived and hard to catch.

excerpt/


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