2001 QW322, The extreme Kuiper belt binary object

silylene old · Nov 4, 2008

This article appeared in last week's issue of Science.  The final paragraph (blue) is interesting, reads like a science fiction story! <img src="http://sitelife.space.com/ver1.0/Content/images/store/6/0/c68cca3e-4e63-44a7-903a-faa2120d6008.Medium.jpg" alt="" />Science 17 October 2008: Vol. 322. no. 5900, pp. 432 - 434 DOI: 10.1126/science.1163148<h2>The Extreme Kuiper Belt Binary 2001 QW322</h2>J.-M. Petit,1,3* J. J. Kavelaars,2 B. J. Gladman,3 J. L. Margot,4 P. D. Nicholson,4 R. L. Jones,5 J. Wm. Parker,6 M. L. N. Ashby,7 A. Campo Bagatin,8 P. Benavidez,8 J. Coffey,3 P. Rousselot,1 O. Mousis,1 P. A. Taylor4 http://www.sciencemag.org/cgi/content/full/322/5900/432We report on the mutual-orbit determination of 2001 QW322, a Kuiper Belt binary with a very large separation whose properties challenge binary-formation and -evolution theories. Six years of tracking indicate that the binary's mutual-orbit period is <img src="http://www.sciencemag.org/math/ap.gif" border="0" alt="{approx}" />25 to 30 years, that the orbit pole is retrograde and inclined 50° to 62° from the ecliptic plane, and, most surprisingly, that the mutual orbital eccentricity is <0.4. The semimajor axis of 105,000 to 135,000 kilometers is 10 times that of other near-equal-mass binaries. Because this weakly bound binary is prone to orbital disruption by interlopers, its lifetime in its present state is probably less than 1 billion years. ...snip....This KBO was discovered in data acquired on 24 August 2001 at the Canada-France-Hawaii Telescope by the Canada-France Ecliptic Plane Survey team. The two components had identical magnitudes of mR <img src="http://www.sciencemag.org/math/sime.gif" border="0" alt="~=" /> 24.0 within the measurement uncertainties, implying essentially equal sizes. Only one other equal-component binary was known at the time, asteroid (90) Antiope, with a magnitude difference of <img src="http://www.sciencemag.org/math/sim.gif" border="0" alt="~" />0.1 mag (5). However, 2001 QW322 was obviously exceptional because the measured separation of <img src="http://www.sciencemag.org/math/sim.gif" border="0" alt="~" />4'' at its distance of 43 astronomical units (AU) corresponds to a sky-projected physical separation of 125,000 km (about one-third of the distance from Earth to the Moon), far larger than any other small-body binary. ...snip..The large separation implied a mutual-orbit period of at least several years. Six years of tracking with the use of 4- to 8-m class telescopes (Fig. 1) resolved that 2001 QW322, an object in the main classical Kuiper Belt (6), has a low-eccentricity mutual orbit with a separation of 105,000 to 135,000 km, greater than any other known minor-planet binary (7). The separation is so large that this nearly equal-mass binary should be incredibly fragile to dynamical disruption, and its continued existence in the middle of the main Kuiper Belt puts strong constraints on the history of the Belt (8). ...snip....The nominal densities shown in Fig. 2 are at the boundary between the density of a low-porosity, pure-water ice body and that of a mixture of water ice and silicate rocks (13). A thermal detection, mutual eclipse, or stellar occultation by the binary (all unlikely) would be necessary to further constrain the size, albedo, density, and hence the bulk composition of 2001 QW322. snip... Given the very large separation (Fig. 3), such a binary is difficult to create and maintain. Of all the proposed KBO binary-formation scenarios (16–19), only the collision of two bodies close to a third one (16) can simply explain the primordial formation of such a system (7). snip...Applying their method to the newly determined orbital and physical parameters for 2001 QW322 and our nominal albedo, we find that the lifetime of this binary is 0.3 to 1 billion years, which is two to three times shorter than the previous estimate. This finding implies one of two things: (i) Either 2001 QW322 was created with its current mutual orbit early in the history of the solar system, in which case it is one of the few survivors of a population at least 50 to 100 times larger, or (ii) this is a transitory object, evolving because of perturbation from interactions with smaller KBOs, from a population of more tightly bound binaries.snip....[This final paragraph from the authors is unusual in a Science paper!]For the likely mutual-orbit parameters, the average orbital speed is  0.85 m/s or a mere 3 km hour–1, a slow human walking pace. An observer standing on one of the components (a very precarious situation, as the gravity is only 0.02 m/s2 or nearly 600 times smaller than on Earth) would see the other component subtend an angle of only 3 arc min, which corresponds to a pinhead seen at arm's length. The existence of the other component would not be in doubt, however, because when viewed at full phase it would be as luminous as Saturn seen from Earth, and it would move perceptibly from week to week. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

silylene old · Nov 4, 2008

I thought this Figure from the above paper was interesting also.  It shows how strange QW322 actually is!<h1>Figure 3 </h1> <img src="http://www.sciencemag.org/content/vol322/issue5900/images/medium/322_432_F3.gif" border="2" alt="Figure 3" hspace="10" vspace="5" width="440" height="312" /> Fig. 3. Secondary-to-primary mass ratio versus average separation (in units of the primary's radius). The dashed box represents the known binary asteroids, all on the left side of the plot (the largest separation barely exceeds 100). Also shown are the most-extreme, outer-planet irregular satellites and several other binary KBOs. The mass ratio q is estimated from the published difference in magnitude between the components, assuming an equal albedo and density for both components. The error bar on the separation for 2001 QW322 accounts only for the uncertainty in the estimated a; it does not account for the (unlikely) possibility that the radius could be off by up to a factor of 2. Nevertheless, with equal mass component and a separation that is more than 2000 times the radius of each component, 2001 QW322 clearly stands out in the top-right corner of this diagram as the widest-orbit, near-equal-mass binary of the solar system. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

MeteorWayne · Nov 4, 2008

As so often is the case, geat catch silylene. ANother issue worth waiting at the mailbox for.We have discovered so many strange critters in the solar system over the last dozen years as our ability to sample the outer reaches has improved and become more complete. It is an amazing time to be alive. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

CalliArcale · Nov 4, 2008

Wow!  That is cool.  A pair of oddballs in the outer solar system. <div class="Discussion_UserSignature"> "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." -- The Tenth Doctor, "Blink" </div>

3488 · Nov 4, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>As so often is the case, geat catch silylene. ANother issue worth waiting at the mailbox for.We have discovered so many strange critters in the solar system over the last dozen years as our ability to sample the outer reaches has improved and become more complete. It is an amazing time to be alive. Posted by MeteorWayne</DIV>It is indeed Wayne.  This is onehell of a strange critter. My guess Wayne is that both compoenents are barely within each others Hill Spheres, so with that reasoning 2001 QW322 has not passed by or has been approached by any large objects through out much of the age of the Solar System. To me that is most interesting. Replying to: <DIV CLASS='Discussion_PostQuote'>Wow!  That is cool.  A pair of oddballs in the outer solar system. Posted by CalliArcale</DIV>I expect they are cool too Calli <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /> At 43 AU they're getting approx 1 / 1,843 the amount of solar energy Earth does. They must be what, approx -250 C. A weird system indeed. Wonder if it would be possible to get spectra of both components in isolation? To see if they are alike.Perhaps once a contact binary as proposed for the Trojan Asteroid 624 Hektor, or one like 216 Kleopatra that broke up??? Strange. Andrew Brown.  <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

silylene old · Nov 4, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> It is indeed Wayne.  This is onehell of a strange critter. My guess Wayne is that both compoenents are barely within each others Hill Spheres, so with that reasoning 2001 QW322 has not passed by or has been approached by any large objects through out much of the age of the Solar System. To me that is most interesting. I expect they are cool too Calli At 43 AU they're getting approx 1 / 1,843 the amount of solar energy Earth does. They must be what, approx -250 C. A weird system indeed. Wonder if it would be possible to get spectra of both components in isolation? To see if they are alike.Perhaps once a contact binary as proposed for the Trojan Asteroid 624 Hektor, or one like 216 Kleopatra that broke up??? Strange. Andrew Brown.  Posted by 3488</DIV> Red:  1. Agrred, I am guessing that the existance of this extreme binary pair puts an lower probability limit on how long it has been, or how close it has been, since another hypothetical star has made a close pass to the Sun, since the time of the formation of the QW322 pair.  I am assuming here that a close pass by another star would likely disrupt this pair, if it got within a certain distance.  (It depends if the QW322 orbit brought it to the same side of the Sun as the approaching hypothetical star at coincidently the same time.  I suspect that the orbital period of QW322 is short enough that the answer to this is likely yes,  that this asteroid pair would be close while the hypothetical star was close enough.)  This means that the 'periodic' extinction events in the earth's fossil history, following the formation of the QW322 pair, are unlikely to be caused by the close pass of another hypothetical star which disturbed the orbits of the KBO's, or perhaps even the Oort cloud; because if it had made a close pass, then this pair would not exist!2. The existance of this extreme binary object probably puts a "NO" on the existance of the hypothetical yet-to-be-discovered big planet X in the Juiper belt, and puts a "NO" on the hypothetical existance of a "Nemesis" undiscovered doomsday dwarf star orbiting the sun which causes periodic extinctions.  (Not that I believed this anyways !)Blue: Maybe the YORP effect spun up a precursor asteroid, which then disintigrated into two equal parts co-orbiting far apart from each other?  Background on the YORP effect: http://news.bbc.co.uk/2/hi/science/nature/6423977.stm <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

silylene old · Nov 4, 2008

Anothr good article.  See the color of the objects (blue). http://www.cfeps.net/CFEPS/Notable_Discoveries/Entries/2008/10/16_2001_QW322_-_the_widest_small_body_binary_in_the_solar_system.html <div id="id1" class="style_SkipStroke_1" style="visibility:visible;width:640px;height:40px"><div class="text-content Normal_External_640_40" style="padding:0px"><div class="Normal">2001 QW322: Antipholus and Antipholus</div></div></div><div id="body_layer" style="margin-left:0px;width:700px"><div id="id2" class="style_SkipStroke_2" style="visibility:visible;width:640px;height:29px"><div class="text-content Normal_External_640_29" style="padding:0px"><div class="Normal">2001 QW322 - the widest small body binary in the solar system</div></div></div><div id="id3" class="style_SkipStroke_3" style="visibility:visible;width:640px;height:23px"><div class="text-content Normal_External_640_23" style="padding:0px"><div class="Normal">Thursday, October 16, 2008</div></div></div><div class="tinyText stroke_0" style="width:377px;height:236px"><div style="width:377px"><img id="generic-picture-attributes" style="visibility:visible;width:377px;height:236px" src="http://www.cfeps.net/CFEPS/Notable_Discoveries/Entries/2008/10/16_2001_QW322_-_the_widest_small_body_binary_in_the_solar_system_files/shapeimage_2.jpg" alt="" /> </div><img style="width:4px;height:232px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /><img style="width:4px;height:4px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /><img style="width:373px;height:4px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /><img style="width:4px;height:4px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /><img style="width:4px;height:232px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /><img style="width:4px;height:4px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /><img style="width:373px;height:4px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /><img style="width:4px;height:4px" src="http://www.cfeps.net/CFEPS/Media/transparent.gif" alt="" /></div><div class="style_SkipStroke_5 flowDefining" style="margin-top:303px;visibility:visible;margin-left:30px;width:640px"><div class="text-content Normal_External_640_1041" style="padding:0px"><div class="Normal"><div class="paragraph paragraph_style_1" style="padding-top:0pt">Discovered by the CFEPS team on 24 August, 2001, Kuiper Belt binary 2001 QW322 was immediately recognized as an exceptional object because the measured separation of 125,000 km (about one third of the distance from Earth to the Moon), far larger than any other small body binary. The two components have nearly identical brightness, implying essentially equal size/mass. <div id="id4" class="style_SkipStroke_4 inline-block" style="margin-top:12px;margin-left:12px;width:312px;margin-right:12px;height:236px"><div class="text-content graphic_textbox_layout_style_default_External_312_236" style="padding:0px"><div class="graphic_textbox_layout_style_default">Antipholus? The CFEPS team calls this pair of objects Antipholus (from Comedy of Errors) since, like the characters from the play, there is almost nothing to distinguish this pair.  Indeed, during conversations regarding the colours and brightness of these sources even the CFEPS team gets confused regarding which object is being referred to.  To be clear; Antipholus A is the one at the bottom of the images and Antipholus B is the one on the top! Don’t forget, Antipholus B is 0.03 mag brighter than Antipholus A.</div></div></div> </div>The large separation implies a mutual-orbit period of more than ten years.  Most small body binaries have orbits of a few months to years in length. Six years of intense tracking by the CFEPS team and our collaborators, using 4-to-8 m class telescopes, revealed that 2001 QW322 has a nearly circular (e < 0.4) mutual-orbit with a separation of 105,000--135,000 km - greater than any other known minor-planet binary - and a period in the range 25--30 years. Observations from VLT and Gemini observatories confirmed that the two components have essentially the same brightness and both components are unusually blue in colour (suggesting an exposed ice surface).  The colour similarity implies a surface similarity, meaning equal surface reflectivity (albedo) for the two components. The most numerous observations in the red filter give a magnitude m_{r'} = 23.7, with an estimated difference of  1 -to- 5%. This is currently the smallest measured brightness difference between components of a binary system in the Solar System. Using our measurement of the brightness and the known distance to the binary, 43.4 AU, we derive a radius of 54 km, based on an assuming a reflectivity of 16% (typical of small objects in the outer solar system). The heliocentric orbit of 2001 QW322 makes it part of the cold main classical Kuiper Belt, a population that has been shown to contain a large fraction of binaries. However, its color is on the blue extreme of the color distribution of that belt's dynamical sub-class. It could then be a low-inclination end-member of the inclination distribution of the hot Kuiper Belt. This latter possibility raises questions on the possibility to retain such a wide binary during the excitation of the hot Kuiper Belt. In the current collisional environment of the Kuiper Belt, the lifetime of 2001 QW322 due to interaction with interlopers is 0.3-1 Gyr. Its formation requires a much denser Kuiper Belt than the present one, thus this binary is certainly primordial. This implies one of two things: (1) Either 2001 QW322 was created with its current mutual-orbit early in the history of the Solar System, in which case it is one of the few survivors of a population at least 50-100 times larger; (2) Or this is a transitory object, evolving, due to perturbation from interactions with smaller KBOs, from a population of more tightly bound binaries. Asserting this latter hypothesis would require better orbital statistics for moderately large KB binaries (separation of 1-2").</div></div></div></div> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

h2ouniverse · Nov 12, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>The existance of this extreme binary object probably puts a "NO" on the existance of the hypothetical yet-to-be-discovered big planet X in the Juiper belt, and puts a "NO" on the hypothetical existance of a "Nemesis" undiscovered doomsday dwarf star orbiting the sun which causes periodic extinctions.  (Not that I believed this anyways !)Blue: Maybe the YORP effect spun up a precursor asteroid, which then disintigrated into two equal parts co-orbiting far apart from each other?  Background on the YORP effect: http://news.bbc.co.uk/2/hi/science/nature/6423977.stm Posted by silylene</DIV>Hi Silylene, I am less inclined to extrapolate the "NO" to a pontic planet in the far reaches. OK to rule it out from the Kuiper Belt proper. But if you have an Earth-massed planet orbiting outside the KB (say with perihelion beyond 52AU, or even higher), you might not disrupt this binary.Moreover, the YORP effect can too (according to calculations in Richardon's, Michel's and al. article  http://www.newsdesk.umd.edu/scitech/release.cfm?ArticleID=1691 ) create a binary by ejection of matter from the primary at equator and reacretion further away forming the satellite. You might then form such binary quite late in the history of the Solar System. Whether YORP can be significant on large bodies from the Sun such as the components of this binary is not obvious though.Also, relative speeds between TNOs are relatively low. From time to time by chance a near-miss disrupts a binary. But from time to time too, a near-miss might form it.Best regards.

3488 · Nov 12, 2008

Hi everyone,Thank you all for the thoughts & updates on here.I wonder if the YORP effect would be too weak at this distance from the Sun?Thank you very much Silylene & Joel for your answers.It appears as if both members are virtual doppelgangers, both visually & spectrally, lending support to either, it is one body that broke up or the two formed together. I think this is something we won't know till there are close up observations from a spaceprobe. However if not mistaken, the individual objects do not appear to really change brightness as the orbit each ther, to me suggesting that both are spherical, assuming they keep the same face turned towards each other like Pluto & Charon. 50 KM a piece wide, so reasonably large. The fact tha both reflect sunlight in exactly the same manner with so little difference in brightness, is fascinating.I too agree totally that this does not bode well to the theory of the existance of a far flung Jupiter like world or Nemesis Brown Dwarf & other such body that has unfortunately led to nonsense like Nibiru, etc.I have long been intruiged by the Jupiter moon's Ganymede resurgence in activity, approx 750 MYO - 1 GYA, postulated by being temporarily yanked into a more elliptical orbit around Jove than usual (by a possible passing massive body), with the resultant increased tides, warming the interior a second time triggering fresh activity for a period (much like Io, but on a vastly reduced scale), before the orbit circularized again by interactions with the other three Galileans.I also wonder if this may have been linked to the most recent Snow Ball Earth episode (not proven beyond doubt, but plenty of evidence does support it), more recent lava plains on Mercury, recently found by MESSENGER, possible resurgance of activity on Mars also about this time, though I need to check for sure, there is now evidence with 2001 QW322 that this may not be so, but then 2001 QW322 (Antipholus & Antipholus) may have been on the other side of the sun as this hypothetical interloper barrelled through approx 1 GYA & remained unaffected. All pieces of a much larger puzzle, of which 2001 QW322 will be an important part.Andrew Brown.  <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · Nov 12, 2008

hi andrew,we do not know either for how long this binary has been like that. They say too that its lifetime should not exceed 1bn years. That is still compatible with many scenarios.It's my belief that the KB is quite dynamic despite the long orbital period. The low kinetic energy of the bodies make it relatively easy for binaries to disrupt and form. And for external perturbations to act. Do not forget too that most n-body modelling of the KB forget to take into account TNO-to-TNO interactions. (TNOs represented as massless particles).Best regards.

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