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Author Topic: lighter than a giant ball of cork  (Read 5183 times)

Offline Gaia

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lighter than a giant ball of cork
« on: 16/09/2006 11:15:03 »
From http://news.bbc.co.uk/1/hi/sci/tech/5346998.stm

This new object, designated HAT-P-1, orbits one member of a pair of stars 450 light-years away in the constellation Lacerta.

Although HAT-P-1's radius is about 1.38 times that of our own Jupiter, it has a mass that is only half that of Jupiter.

This makes it much bigger and lower in density than planets are usually, raising questions about how it formed.

The mathematical equations describing planetary structure do not fit.
It would float in a bathtub if you could find a tub big enough to hold it
Gaspar Bakos

"This planet is about one-quarter the density of water," said Gaspar Bakos, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics (CfA).

"In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher."

HAT-P-1 is the largest of the 200 or so planets that have been detected outside our Solar System.

Like many of these extrasolar bodies, it orbits close to its parent star, revolving around it in just once every 4.5 Earth days.

Scientists know of one other extrasolar planet, HD 209458b, which is also puffed up about 20% bigger than predicted by theory. HAT-P-1 is 24% larger than expected.



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Offline bostjan

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Re: lighter than a giant ball of cork
« Reply #1 on: 18/09/2006 03:20:05 »
Hat-P1 sounds like an interesting place.  It's pretty far away, though, so we may never know why it's so sparse.
 

Offline Soul Surfer

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Re: lighter than a giant ball of cork
« Reply #2 on: 18/09/2006 11:15:43 »
I think that the method of detection probably has something to do with it.  My guess is that it was found using the eclipsing technique or its physical "size"  would not be known.  The closeness to the primary would extend the atmosphere of the planet because of its extreme heat but as well as this, the refraction of the high atmosphere would also extend the size of the obscuration and lower the density estimate.  One normally sizes objects like planets by the physical obscuration and opacity of the atmosphere but the refraction extends further than this.

My guess is that the observers were well aware of this effect but stessed the anomaly to help the publicity of their work  :-)

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Offline science_guy

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Re: lighter than a giant ball of cork
« Reply #3 on: 18/09/2006 16:05:28 »
You never know how far into any one given area of space.  Scientists use a technique with a telescope that finds to large gravitational bodies, and look between them.  The opposing gravitys act as a natural magnification.  They may of found one of these and actually saw the basic size of the planet.

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Offline bostjan

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Re: lighter than a giant ball of cork
« Reply #4 on: 18/09/2006 03:20:05 »
Hat-P1 sounds like an interesting place.  It's pretty far away, though, so we may never know why it's so sparse.
 

Offline Soul Surfer

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Re: lighter than a giant ball of cork
« Reply #5 on: 18/09/2006 11:15:43 »
I think that the method of detection probably has something to do with it.  My guess is that it was found using the eclipsing technique or its physical "size"  would not be known.  The closeness to the primary would extend the atmosphere of the planet because of its extreme heat but as well as this, the refraction of the high atmosphere would also extend the size of the obscuration and lower the density estimate.  One normally sizes objects like planets by the physical obscuration and opacity of the atmosphere but the refraction extends further than this.

My guess is that the observers were well aware of this effect but stessed the anomaly to help the publicity of their work  :-)

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Offline science_guy

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Re: lighter than a giant ball of cork
« Reply #6 on: 18/09/2006 16:05:28 »
You never know how far into any one given area of space.  Scientists use a technique with a telescope that finds to large gravitational bodies, and look between them.  The opposing gravitys act as a natural magnification.  They may of found one of these and actually saw the basic size of the planet.

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Offline Soul Surfer

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Re: lighter than a giant ball of cork
« Reply #7 on: 18/09/2006 23:07:50 »
Science guy you appear to be talking total tripe even the english is questionable in that post.

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Offline bostjan

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Re: lighter than a giant ball of cork
« Reply #8 on: 19/09/2006 08:28:14 »
Oh yeah, one of the discoverers was on the radio, so I'll bet they are enjoying the publicity.  I think all 200+ extrasolar planet discoveries should be pulicised (sp), though.  I've honestly only seen or heard of three that were available in popular magizines or newspapers.  I still think these observations are of interest to astronomers.  Why even be an astronomer if not to search for other worlds?  (Or in Carl Sagan's case, smoke pot and hallucinate giant jellyfish swimming around Jupiter lol)
 

Offline Soul Surfer

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Re: lighter than a giant ball of cork
« Reply #9 on: 18/09/2006 23:07:50 »
Science guy you appear to be talking total tripe even the english is questionable in that post.

Learn, create, test and tell
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Offline bostjan

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Re: lighter than a giant ball of cork
« Reply #10 on: 19/09/2006 08:28:14 »
Oh yeah, one of the discoverers was on the radio, so I'll bet they are enjoying the publicity.  I think all 200+ extrasolar planet discoveries should be pulicised (sp), though.  I've honestly only seen or heard of three that were available in popular magizines or newspapers.  I still think these observations are of interest to astronomers.  Why even be an astronomer if not to search for other worlds?  (Or in Carl Sagan's case, smoke pot and hallucinate giant jellyfish swimming around Jupiter lol)
 

Offline sheesh

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Re: lighter than a giant ball of cork
« Reply #11 on: 17/10/2006 22:50:04 »
science guy may not be well informed but gravitational lensing can be used to basically focus light from more distant objects but it has its own inherant distortions.

 But from what i've read this was calculated using the eclipsing method, even accounting for the margin of error in this technique has anyone considered good old newtonian physics?  This planet could have been created by a collision by a meteor or commet impacting the surface on a large scale, perhaps even  planets colliding the energy release would be more than sufficient to destabilise a planet's atmosphere.

 It could also be a rogue planet caught caught by the star but the odds are more than against this.

 Last but not least has anyone considered what happens to a meteor/comet that gets drawn to close to a star? rough guess it would be torn apart and roasted by solar energy. One big ball of gas held together by its own gravity but not large enough in its own right to be drawn into the sun tumbling through a stable orbit.

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Offline science_guy

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Re: lighter than a giant ball of cork
« Reply #12 on: 19/10/2006 16:05:10 »
quote:
Science guy you appear to be talking total tripe even the english is questionable in that post.

Whats so questionable about that post?  ill admit that i did a minor grammar error in the first sentence and accidentally put "to" instead of "two" but what is the problem with what i am telling you?
quote:
science guy may not be well informed but gravitational lensing can be used to basically focus light from more distant objects but it has its own inherant distortions.


Ive never known the specifics, but I know that gravitational lensing exists.

quote:
Last but not least has anyone considered what happens to a meteor/comet that gets drawn to close to a star? rough guess it would be torn apart and roasted by solar energy. One big ball of gas held together by its own gravity but not large enough in its own right to be drawn into the sun tumbling through a stable orbit.


When somthing reports close to the sun, that doesnt mean that it is close in a human perspective.  When Astronomers are talking about gas giants being close to the sun, they mean that it is close compared to our solar system.  Scientists have discovered that outside our solar system, none of them actually are configured the way that our solar system is.  In all of the solar systems we have discovered, the terrestial planets are on the outside, while the gas giants are on the inside.



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Re: lighter than a giant ball of cork
« Reply #12 on: 19/10/2006 16:05:10 »

 

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