Cosmic oddball stirs up planet debate - October 07, 2008
Posted on behalf of Ashley Yeager
To be or not to be; that always seems to be astronomical question—especially when it comes to being a planet.
Sadly, Pluto and its brethren are too small. Failed stars are too big. Now, some candidates might just be too dense. So it could up to Goldilocks to decide what’s “just right.” Or, at the very least, she might know whether COROT-exo-3b can be a part of the planet club.
Earlier this year, astronomers discovered the anomalous object with the French-Space-Agency-led COROT (COnvection ROtation and planetary Transits) satellite. Turns out the potential planet swings around its parent star—which is slightly larger and more massive than the sun—in a mere four days and six hours. Now, that’s by no mean an exoplanet record. But, add to that speed the fact that COROT-exo-3b is about the size of Jupiter yet is 21.6 times more massive, and then there’s a problem. The object is more than twice as dense as lead—a characteristic never seen before in planets, ESA reports in a press release.
If COROT-exo-3b is in fact a planet, it will be the most massive and the densest found to date. If Bad Astronomer Phil Plait were able to stand on its surface, he says he would weigh 4,200 kilograms, (although he doesn’t reveal how much he would weigh on Earth for comparison). Other details about COROT-exo-3b will appear in an upcoming issue of Astronomy and Astrophysics.
Scientists, however, are still debating whether to call this object a planet because it’s so unlike anything they’ve ever seen. They’ve tried considering COROT-exo-3b as a failed star—something too massive to be a planet but too weak to burn hydrogen and shine like a star—but it doesn’t quite fit in that class either.
COROT-exo-3b “might turn out to be a rare object found by sheer luck,” Francois Bouchy of the Institut d'Astrophysique de Paris told ESA. Or, the potential planet’s co-discoverer said, it might actually be a “member of a new-found family of very massive planets that encircle stars more massive than the sun.”
Bouchy added that based on the find astronomers are now starting to think that the more massive a star is, the more massive its planets might be.
Image: ESA
Comments
Whats this planet made of then. lead has density of 11.3 so this planet has a density of 22.6 approximately. Only elements that dense are platinum, osmium and iridium (and a few exotic nucleides with tiny half-lives). I know solid elements become denser at high pressure but I would'nt have thought to that extent. Could it have eaten a small neutron star or something?
frank
Posted by: frank davis | October 7, 2008 03:21 PM
This is an objection to the statement, "sadly, Pluto and its brethren are too small" to be planets. This represents only ONE point of view and is not accepted by many professional astronomers. Please do not blindly follow a dictate of four percent of the IAU, most of whom are not planetary scientists--a dictate immediately opposed by an equal number of professional astronomers in a formal petition. Many believe that a better definition of planet is any non-self-luminous spheroidal body orbiting a star. If the object is in hydrostatic equilibrium, meaning it has enough self gravity to pull itself into a round shape, it's a planet. When an object reaches this size, it experiences differentiation and the same geological processes as the classical planets. That is a sound-enough reason to classify dwarf planets as a subclass of planets. They may be smaller, but they are large enough to be small planets nevertheless.
Posted by: Laurel Kornfeld | October 7, 2008 04:24 PM
Perhaps it's a Dyson sphere with a neutron star inside it. I would think it would need to be made of very dense materials to contain a star. Everyone would probably be plastered to one side with that orbital velocity though.
http://en.wikipedia.org/wiki/Dyson_sphere
Posted by: Keston | October 9, 2008 01:39 AM
In response to Frank, it's very possible that the planet is made up of many more things than the elements you mention. Keeping in mind that Jupiter is primarily made of hydrogen and helium, it would suffice that the dominant elements were at least 22.6 times as dense as hydrogen and helium and similarly compressible.
I can't speak towards the actual compressibility of the elements, but if we make the hand-wavy assumption that all gases are roughly equally compressible then a chlorine/argon mix would be more than sufficient to create a planet of roughly Jupiter's size and more than 20 times its density.
If solids exhibit this same behavior, then it would be plausible that the planet were made of boron or carbon (and this would be far more likely to occur naturally at atomic numbers 5 and 6 than chlorine and argon at 17 and 18, respectively).
Posted by: Stephen Horn | October 9, 2008 02:22 AM
Ya. Stop picking on Pluto! And lets call CoRotExo#b CarrotHead for short!
Posted by: Donroy | October 9, 2008 04:45 AM
Euhm frank : a stronger gravity will make materials more dense.
The density of hydrogen gas in vacuum is next to nothing, yet the sun's corona, full of the stuff, quickly becomes more dense than the earth's crust.
So just because a material has a certain density at normal pressure 1G and 1atm does not mean it can't be compressed by gravity (and no doubt if there's an athmosphere it'll be terribly dense)
Posted by: Tom | October 9, 2008 09:41 AM
Laurel - It's over. There is good reason for the decsion they made, and many Astronmer accept it.
The mre strict definitions of a planet mean Pluto isn't a planet..just like the thousand of other object aren't. It was not a decision to 'get Pluto'.
You can pout all you want, but don't waste are time with your non science based emotional abjection to what we label a ball of ice.
Posted by: Garrett | October 9, 2008 11:58 PM
Does anyone understand how they measured the mass of the planet?
Posted by: Harry Johnston | October 10, 2008 03:01 AM
Article says:
the size of Jupiter yet is 21.6 times more massive, and then there’s a problem
What's the problem? Its density? It's caused by the gravity, so that's no mystery. And despite having a density of lead twice, it is not necessary it is composed from über-lead, just any matter compressed hard enough.
It's a pretty well known exoplanet fact, that planets and later brown dwarfs are as big as Jupiter, but no more, irrespective of mass.
Posted by: tomas kindahl | October 11, 2008 08:50 AM
I label this a new category of planets and I propose the name "cindroids". As I understand it solid planets heavier than earth have correspondingly more heavier elements inside their cores and a higher energy level of nuclear decay as well as magma energy created by collapse. Even not considering the heat of the man star, the planet itself will not have a solid crust. All lighter elements will have blown off and the crust will be largely white hot seas of sulphur, potassium and carbon. The core of this planet will be almost pure iron. Finally, the planet will not only be hot from isotope decay, solar radiation, heat caught inside by gravitational collapse - but my aurora globalis as well. At a range of under a million miles this will be bright enough to cloud the planet in a blanket of neon glow, obscuring the surface in electrical current. The thing will be white hot, not just from being cooked, or lava seas, but fom being electrocuted by particle flows. The magnetic field will have an effect on the main star too, creating potentially visible particle field lines between the star, back and forth. I would stay away from the trailing particle tail in the wake of this planet - it will be like a nuclear blast. My bet is this star will literally be braking in mid-space due to magnetic interaction with the main star. It will plunge in the star in geologic timescales.
Posted by: Khannea Suntzu | February 15, 2009 04:56 PM
Garrett--it's NOT over even though you may wish it were. There are plenty of astronomers who do not accept the IAU definition. Something does not just become fact because a group of people decrees it so. The IAU could rule that the sky is green; that wouldn't make it any less blue.
If you have to use personal attacks such as accusing me of "pouting" or being "emotional," that means you don't have a real answer to the issue.
Maybe these links will help you:
http://www.ipetitions.com/petition/planetprotest/
http://gpd.jhuapl.edu/
http://www.sciencenews.org/index/generic/activity/view/id/38770/title/Debates_over_definition_of_planet_continue_and_inspire
Posted by: Laurel Kornfeld | May 18, 2009 11:39 PM