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Kullat Nunu
2011-Aug-25, 07:37 PM
A new pulsar planet (http://scienceblogs.com/catdynamics/2011/08/pulsar_in_the_sky_with_diamond.php) discovered.

A weird one.

Mass 1 MJ, orbital period 2.2 hours! Since it is not losing mass, it has to be incredibly dense -- at least 23g/cm3, possibly much more. Apparently a former white dwarf, now pure diamond.

chornedsnorkack
2011-Aug-25, 08:07 PM
Is there any evidence it is carbon?

How dense would rock be at 1 Jupiter mass? How about iron?

korjik
2011-Aug-25, 10:15 PM
carbon is much more common than iron, and the main constituent of a white dwarf.

Article says that the planet would pretty much have to be a solid crystalized core of a white dwarf to have the characteristics it has

chornedsnorkack
2011-Aug-26, 02:53 PM
carbon is much more common than iron, and the main constituent of a white dwarf.
But is carbon more common than oxygen or silicon?


Article says that the planet would pretty much have to be a solid crystalized core of a white dwarf to have the characteristics it has

What kind of arguments does the article have to support this?

KaiYeves
2011-Aug-26, 03:05 PM
*Insert Krypton Joke*

Cougar
2011-Aug-27, 12:57 AM
What kind of arguments does the article have to support this?

Here's the paper out of swinburne.edu.au in pdf format: Transformation of a Star into a Planet in a Millisecond Pulsar Binary. (http://www.swinburne.edu.au/chancellery/mediacentre/resources/Diamond-planet-Science.pdf)

The abstract says....






We show that it is in a binary system with an orbital period of 2.2 h. Its companionís mass is near that of Jupiter, but its minimum density of 23 g cm−3 suggests that it may be an ultra-low mass carbon white dwarf.

An orbital period of 2.2 hours! That baby's deep in the gravity well of that pulsar. Apparently they use the fact that...






For large mass ratios, the Roche Lobe radius of the companion [can be] well approximated... and dictates the maximum dimension of the companion star.

astromark
2011-Aug-27, 05:39 AM
I find this sort of article misleading to the enth degree... Its not just wrong. Its very wrong.

Damaging to good science and enough to turn good people away from the science we all love...ASTRONOMY.

and NO. I am not challenging the data found.. that is great. I am not even challenging the published results..

Just the way in which Dense carbon ( crystallized ) is called diamond.. Please call it carbon. Densely compacted carbon...

A local newspaper made comment of twinkling as like diamond.. and I get late night phone calls asking me.. Are stars diamonds ? Sigh...

Yes I understand that pure carbon is diamond... but this is not a known fact here... misleading news hype. Tabloid rubbish.

Kullat Nunu
2011-Aug-27, 07:02 AM
I find this sort of article misleading to the enth degree... Its not just wrong. Its very wrong.

Damaging to good science and enough to turn good people away from the science we all love...ASTRONOMY.

Exactly why it is wrong? If there is a Jupiter-mass diamond orbiting a pulsar, then there is. Good example why astronomy is so damn COOL.


A local newspaper made comment of twinkling as like diamond.. and I get late night phone calls asking me.. Are stars diamonds ? Sigh...

I understand your frustration...


Yes I understand that pure carbon is diamond... but this is not a known fact here... misleading news hype. Tabloid rubbish.

Rubbish? Couldn't disagree more. This kind of news is stuff that makes people interested in astronomy!

(The fact that some scientists make lot of media noise from unverified results, and that some journalists are experts in distorting the actual news is completely different thing.)

astromark
2011-Aug-27, 08:06 AM
Well...yes that is my point.. I agree with you., but as to the 'Rubbish' comment. I will not altar my view... This sort of miss information I would think costs astronomy sensible people.. On reading diamonds in space..I would turn it off. That was my point. That first news release should have been... 'Purest carbon star observed.' and for goodness sake would the facts have spoilt this... no.

and I add that the whole slightly complicated story has NOT been well reported.
I needed to research myself to establish the facts as known.. The tel tale orbital velocity and the obviouse mass of densaty.. detected..
could be what we know as diamond.. but the state of mater at this densaty and heat is not familure to us is it... ?

Jeff Root
2011-Aug-27, 08:09 AM
Really hot ice!

Even after it cools off (after a trillion years or so), it will be
hard to fence. It will be identifiable by its impurities even
after it has been cut up.

-- Jeff, in Minneapolis

Kullat Nunu
2011-Aug-27, 08:12 AM
Well, IMHO, "purest carbon star" would have been more misleading, as the object is no longer a star and its purity is questionable. :) There are carbon-rich white dwarfs.

astromark
2011-Aug-27, 09:11 AM
and I can agree with that also.., but the truth should not be compromised or distorted because of 'copy'...

PaulLogan
2011-Aug-27, 03:09 PM
This sort of miss information I would think costs astronomy sensible people.. On reading diamonds in space..I would turn it off.

i couldn't disagree more.

people who turn off or away when they encounter a concept they cannot fathom or otherwise doesn't make sense to them are not the kind of people science needs anyways. science is infested by closed-mindedness and rejection as it is. the kind of people science needs will want to learn more and get to the bottom of it when they hear "diamonds in space".

marsbug
2011-Aug-27, 03:15 PM
While 'diamond planet' is misleading, even 'dense carbon planet' is based on data inferred rather than observed (ie its not definitively a carbon planet until the surface can be tested directly).

That said :'Observations made that do not disprove the hypotheis of planet-like former stellar object having some significant quantity of densley compacted (possibly crystalline) carbon, concieviably anolagous to terrestrial diamond' does not make for a headline accessable to the masses.

Me, I'd have put: " 'Diamond planet'? Well, in sense perhaps." before writing as accessable an explanation as I could.

It's not good to distort the facts but its much worse to alienate someone.

Paul Wally
2011-Aug-27, 09:11 PM
A critical attitude is the more sensible approach. Dismissing something as nonsense without providing reasons is just as wrong as believing something without question. Now, are there reasons to believe that this planet made of carbon cannot assume a global crystalline form? Perhaps the intense pressure at it's core will break the crystal structure and then the lack of pressure at the surface means that diamond can never form. So I speculate that diamond will only form in a region somewhere between the core and the surface, perhaps a diamond mantle?

starcanuck64
2011-Aug-30, 09:14 PM
Whatever they want to call it, it's amazing we can infer the presence of such objects at such distances, 4,000 light years! and suggest what they might be composed of.

eburacum45
2011-Sep-03, 12:29 PM
Whatever this is, it isn't really a planet, more a stelllar remnant.

Several questions; how would a star get to have such a low mass when it becomes a white dwarf? Would it be a high-mass star that has lost nearly all its mass, in a supernova explosion for example?
The pulsar itself was presumably formed in a supernova explosion - did this explosion strip the companion star of a large fraction of its mass? If so how can it still be in such a close orbit?
How old is the pulsar? I believe this can be determined from the spin rate.
I wonder what colour/temperature the white dwarf/object might be.
Might this object have formed during or just after the supernova somehow?

I don't expect anyone to have answers for all these questions, by the way- I'm just thinking aloud.

eburacum45
2011-Sep-03, 12:34 PM
From Wiki
http://en.wikipedia.org/wiki/PSR_J1719-1438


The companion is likely the remnants of a star whose outer layers were siphoned off by the more massive pulsar.
Well, that answers some of my questions.

Kullat Nunu
2011-Sep-05, 06:13 AM
Whatever this is, it isn't really a planet, more a stelllar remnant.

Well, that is a matter of opinion. Whatever it was before, with that mass it is no longer a proper white dwarf. If we consider any substellar circumstellar objects as planets (minus brown dwarfs), then it definitely is a planet. But if being a planet requires it has to be born from a circumstellar disk, thinks get a lot muddier. How do we know if a massive planet is was born through accretion or disk instabilities (planet) or from collapsing gas cloud fragment (not planet)?

Taking your argument to the extreme, aren't all planets stellar remnants? They are made from stuff that was originally part of a star... ;)

Ivan Viehoff
2011-Sep-07, 12:14 PM
"Diamond" is surely defined by its crystal structure. For example, graphite, a different form of carbon with a different crystal structure, is not diamond. At normal pressures, diamond has a density of 3.5 g/cm3, and graphite is rather lighter. As is known for the case of water ice, which like diamond has a tetrahedral crystal structure at standard pressures, at high pressures such crystal structures are distorted; you can even interleave one tetrahedral lattice through another one at sufficient pressure, in the case of water anyway. Whatever crystal structure carbon has when compressed to at least 23g/cm3, it sure isn't diamond.

ryanmercer
2011-Sep-08, 11:10 PM
Whatever they want to call it, it's amazing we can infer the presence of such objects at such distances, 4,000 light years! and suggest what they might be composed of.

^this, very much this. *nods*

neilzero
2013-Jun-08, 04:34 PM
Bump: 1.9 years later, there should be some better analysis? If the average density is 23.5 then the center of mass density should be much higher and the surface density more like the 3.5 density of diamond at standard temperature and pressure. Eventually we will needs some names for objects with densities between gas giant planet centers and white dwarf centers. I see little reason for the "planet" to be more than 50% carbon with about 1000 other elements and isotopes likely, especially as iron is the last thing to fuse, if there is not enough mass for a super nova. Do some red giant stars last fuse carbon instead of iron? Neil

ryanmercer
2013-Jun-08, 04:44 PM
You'd think so

Bynaus
2013-Jun-08, 09:21 PM
White dwarfs consist of Carbon and Oxygen (or Neon and Oxygen, in rare cases) exactly because their predecessor stars didn't have enough mass to fuse C/O (O/Ne) into heavier elements. If they had, the mass of the remnant would have been so high as to exceed the maximum mass limit of white dwarfs, i.e., the core of the predecessor star had formed a pulsar (neutron star) in a supernova.

neilzero
2013-Jun-09, 02:11 AM
That seems reasonable, but will more than 90% of the oxygen, neon, helium and hydrogen get fused to carbon or expelled if there is not enough mass to become a neutron star? Didn't the main sequence star have almost 100 other elements, that didn't fuse? Pure carbon seems unlikely. Neil

Ilya
2013-Jun-25, 05:44 PM
So it's a diamond, but not gem-quality