IAU looking to decide if 2003 UB313 is a major planet

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>What if it has no observable moon? How would you measure the mass? <p><hr /></p></p></blockquote><br /><br />If there's nothing convenient for it to perturb, the normal means is to determine the object's position and then make visible and infrared measurements of it. These allow you to put certain bounds on its possible size (volume, not mass). Then you make an educated guess about the density based on what you believe it to be made of. Spectroscopy readings are enormously helpful with that, although these can be hard to get for really remote objects.<br /><br />This does, of course, leave the possibility of controversy if an object without a moon is found to be somewhere in a range of masses which neatly straddles the arbitrary definition of a major planet (assuming they go by mass -- or volume, for that matter), and the possibility of an object being promoted or demoted on the discovery of new information. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mpai]

Any updates on 2003 UB313? Spitzer was to watch it in August end while the Hubble Space Telescope is scheduled to observe in November and December?<br />

 

[Philotas]

Hm, well, Jupiter is one of the ancient planets, so it must stay a planet. Also because its size it must be a planet; all gas planets are that big that they must be considered planets. <br /><br />It might be better to change my defintion for a planet into: 'an object with enough mass to form itself into a sphere.' Wich means 2003 EL61 is a planet because it has the potential to be spherical, but its rapid rotation prevents that to happen. Asteroids are not planets because they do not have the potential to be spherical.<br /><br />Diameter isn`t too easy to measure, objects that appear to be />2200 km in diameter from Earth, may well be proven to be 1900 km in diameter after a close pass by a spacecraft. So over the night the object is suddenly no longer a planet. <div class="Discussion_UserSignature"> </div>

 

[CalliArcale]

I haven't heard anything yet, mpai. Most likely we will have to wait for a press conference; with these sorts of instruments, images aren't guaranteed to be released to the public until one year after they are acquired. This is to give the original investigators (the ones who signed up for these observations) first dibs at any scientific publication. If I were them, I'd probably wait until after all of the pics had been obtained so I could take care of it all in one press conference. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mikeemmert]

Hi, Philotas, appreciate your replies...<br /><br />I have been googling today and I came up with this paper on 2003 EL61:<br /><br />http://64.233.167.104/search?q=cache:-Is9XpqwZXEJ:www.gps.caltech.edu/~mbrown/2003EL61/rabinowitz.pdf+2003+EL61+Arizona&hl=en<br /><br />or:<br /><br />http://tinyurl.com/boxpd<br /><br />(I hope these links work).<br /><br />Maybe this will shed more light than heat on these objects. This is kind of technical, sorry about that.<br /><br />Note the discussion on Mclaurin oblate spheroids vs. Jacobian squashed ellipsoids. Also, when a potential size is computed, 2003 EL61 (herinafter refered to as Santa) could be as much as 2500 km in it's longest dimension, which would make it longer than the diameter of Pluto.<br /><br />Santa throws a monkeywrench into this discussion. It makes the idea of "round" a little harder to define.<br /><br />Note the very high density of Santa. That and the rapid spin says it got whacked by something big traveling very fast. I'm working with GravitySimulator right now on objects with very high inclination (up to 40 degrees in the simulation running right now, a third generation simulation) which pass through the Sun/Neptune Lagrange points L4 and L5. So far, they seem to be stable. Backing up the simulation is the observation of Cruinthe, an asteroid with an extreme inclination that is in a horseshoe orbit around the sun at about 1 AU that is perturbed into slightly higher and slightly lower semi-major axis by Earth. It seems to be stable. I think this thing is 4 1/2 billion years old and hasn't come out of this orbit, so high-inclination orbits that pass through the Lagrange points seem to be stable. I'll have to wait on my dinky little computer.<br /><br />Maybe Santa got whacked by Pluto? Still worki

 

[bonzelite]

you divide them up by stratification, like in tree rings. you have the Inner Planets, the Gas Giants, then the Outer Planets --the Kuiper Planets and the Oort Planets. you could even then have the Termination Shock Planets and Heliopause Planets. so in coversation, you can say "and as we observe Xena, a Kuiper Planet, we will notice the high concentration of metallic methane blah blah blah blah..." this also keys us in to where it is --we will instantly know it is among the distant planets.<br /><br />this way, we keep our original and habitual traditional nine planets whilst taking into account ever deeper sky objects that will be found for centuries to come ---those that are round or round-ish, and are as large as Mercury or Pluto or larger. <br /><br />the issue is just gonig to get worse the more we discover celestial bodies of notable size and roundness.

 

[teije]

The trouble with the words planet and moon is that they are rapidly becoming outdated.<br />'Planet' is derived from the ancient greek word for 'traveller' meaning that they were the things that moved through the heavens. There were 5 of them named after important Gods.<br />Mercury, Venus, Mars, Jupiter, and Saturn. (Although those are their Roman names, I'm not sure if the Greeks called them Hermes, Aphrodite, Ares, Zeus, and Cronos.) <br />The moon was just that. The moon. There was only 1 of it's kind, no need for classification. <br />Same goes for the sun.<br /><br />Now, as the ages passed, some nasty things happened. First was the discovery that the Earth moved around the sun just like the 5 planets. It wasn't a big deal (from a definitions' point of view anyway) and the earth was dubbed a planet. And the definition of planet was reviewed as 'a world orbiting the sun' of which there were now 6<br /><br />Then the Galilean moons of Jupiter were discovered. Not too bad either, they were called moons, 'THE' moon lost it's unique status, and 'moon' was redefined as 'a world orbiting a planet.'<br /><br />Discovery that the sun was a star and the stars were suns wasn't too bad, the words became more or less synonimous. Uranus and Neptune were planets, that was obvious. 8 of them now. But now, trouble starts arising.<br /><br />Smaller worlds like Ceres and Vesta are discovered, then Pluto, which at least for a while held planet status. People start talking about Asteroids, Planetoids, minor planets, comets, Trojans, KBO's, etc. etc. etc.<br /><br />Nature fooled us again. Our neat little classes no longer fit. New definitions are needed, as already proven by some posts in this thread. Some good proposals there as well. <br />One lucky break: A definition is just that. A definition. You can change it if you wish, and it is always correct because it is a definition. I myself don't presume to know enough about astronomy to be able to redefine classes of celestial objects. But I'm

 

[Philotas]

Interesting indeed. Now I`m just wondering if Santas rotation will slow down with time, or whether it will keep stable(supposed its not hit by more objects and alike) for the next million/billion years. <br />Uranus was evidently hit pretty hard in the past, but its rotation period is not unnormal, if I recall it correctly. Or didn`t Uranus speed up its rotation at all? Is Santa somewhat unique because of the way the collision happened, or has the collision happened more recently? Shouldn`t there be more of these objects? <div class="Discussion_UserSignature"> </div>

 

[mikeemmert]

Hail, Philotas;<br /><br />I would refer you to this link, provided for other readers (since I originally got it from you, thank you):<br /><br />http://www.ifa.hawaii.edu/faculty/jewitt/kb.html<br /><br />On the left hand margin are sublinks to related subjects. Among these are "The Edge of the Kuiper Belt" and "Binaries". There are about a thousand known KBO's, and nine of them are binaries. The Binary link remarks that this is too many, that the Kuiper Belt must have been denser than they thought. However, if that's true, why is there an edge to the Kuiper Belt at 47 AU? <br /><br />I think most of these objects formed at the Sun/Neptune Lagrange points L4 and L5. In doing GravitySimulator depictions of these places, I have discovered that you can have a perfectly enormous inclination, up to 40 degrees (and probably beyond, these simulations take time to run), of objects passing through the Lagrange points and they are in stable orbits.<br /><br />I think early in the history of the Solar system, these were density nodes. So there was more material there than in the belt outside of Neptune's orbit. So it looked a lot more like a belt than a disc. There would be friction there from a little bit a gas and a great deal of fine dust replenished by collisions. As a result, these zones could trap more material that was in eccentric or horseshoe orbits.<br /><br />I'm quite sure Xena and Triton formed as a binary in one of these Lagange zone; otherwise there is no explanation for how Triton got captured by Neptune or how Xena got into such a far orbit. Simulations I've done so far (and I'm certainly not through with this series) seem to back that up.<br /><br />More speculative is the idea that Pluto and Santa formed at opposite extremes of the zone and collided near the Lagrange point. I'm a lot less sure of this. One nagging question is how Pluto retained most of it's ices and Santa lost most o

 

[mikeemmert]

They might as well define the other end of the size scale, while they're at it. That seems easier. An object larger than 13 Jupiter masses will fuze hydrogen and deuterium to form helium 3. It is therefore a star. When it runs out of deuterium, then it is a dead star. They're called "brown dwarfs" and that's a good name; since most brown dwarfs are probably out of deuterium and are "dead brown dwarfs" there is really no need for the word, "dead". Rather, an object that hasn't run out of deuterium is a "live brown dwarf".<br /><br />I wonder if certain very rare isotopes might have a lower fusion threshold? Beryllium 7 is produced by cosmic ray bombardment of the interstellar medium, as well as in the Sun by the fusion of helium 3 and helium 4, where it doesn't last long before it fuses with a proton to form boron 8, which decays into a neutrino, a positron, and a two alpha particles.<br /><br />If less than 13 Jupiter masses will ignite beryllium 7 or some similar rare isotope, then that mass would be the lower limit for a star, even if the fuel only lasts for a few weeks. I can't understand why the proton-proton reaction defines stardom. Wolf-Rayet stars and the progenitors of type I supernovae (Ia, Ib, and Ic) do not have hydrogen and so cannot be using the proton-proton reaction, and yet they are called stars. Neutron stars don't even DO fusion and they are called stars.<br /><br />Does anybody out there know what the minimum mass for a beryllium 7 star is?

 

[vogon13]

Beryllium 7 ? <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[Philotas]

<blockquote><font class="small">In reply to:</font><hr /><p>More speculative is the idea that Pluto and Santa formed at opposite extremes of the zone and collided near the Lagrange point. I'm a lot less sure of this. One nagging question is how Pluto retained most of it's ices and Santa lost most of it's?<p><hr /></p></p></blockquote><br /><br />Do you assume that a collision with Pluto made Santa spin to sigarshape? <br /><br />I would imagine that a collision between to equal sized bodies would end in front collision and that the ice on both objects would evaporate, so I would assume that if Pluto has more ice than than Santa, it has to be because of more frequent impacts in Plutos region.<br /> <div class="Discussion_UserSignature"> </div>

 

[mikeemmert]

Hail Philotas;<br /><br />Making hypotheses is tough. Thanks for the idea about frequent impacts in the Pluto region.<br /><br />According to simulations I have done, Santa could have spent some time inside Neptune's orbit before being perturbed back out again. Maybe the ice evaporated at that time. But then, water ice would remain frozen, so that doesn't work so well.<br /><br />Basically, Santa seems to be the leftover core of a Pluto-sized object. That's the main idea I'm working on right now. It's backed up by the mass measurement made possible by Santa's moon, which imply that the object is made out of mostly rock. So now I have to explain all the implications of that and it's not easy.<br /><br />Thanks for posting and don't worry that your questions are tough to answer. At some point, somebody has to answer questions like that, so fire away <img src="/images/icons/smile.gif" />

 

[Philotas]

That cleared things up, thanks. <div class="Discussion_UserSignature"> </div>