Eris
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Xena, and it`s moon
Gabrielle, (Now named (136199) Eris, and Dysnomia) is a large Kuiper belt Object in the solar system.
The discovered object is one of the farthest-known objects in the solar system, orbiting the sun once every 557 years. Eris is a typical member of the Kuiper belt, but its sheer size in relation to the eight known planets means that it was classified as a dwarf planet. The astronomers inferred the size of the object by its brightness. The reflectance (its albedo) of the planet is not yet known, but it put a lower limit of 2,302 kilometres (1,438 miles) in diameter, on its size. (Updated 13thApril 2006 ) "Even if it reflected 100 percent of the light reaching it, it would still be as big as Pluto. I'd say it's probably one and a half times the size of Pluto, but we're not sure yet of the final size. " -Dr. Mike Brown, California Institute of Technology. An upper limit of 3,000 kilometres was placed by the non-detection of the object using the Spitzer Space Telescope. is unable to detect the new object, the overall diameter must be less than 3,000 kilometres . The dwarf planet , with the current temporary name 2003UB313, was discovered using the Samuel Oschin Telescope at Palomar Observatory near San Diego, California, by astronomers Mike Brown (Caltech), Chad Trujillo (Gemini Observatory), and David Rabinowitz (Yale University). The object was first photographed on Oct. 31, 2003, but it was so far away that its motion was not detected until data was analysed again in January 8 2005. The new planet went undiscovered for so long because its orbit is tilted at a 44-degree angle to the orbital plane of the other planets. In 2004 scientists discovered Sedna, a remote world that is 1,700 km across. Currently Sedna is 91 AU distant. At the far end of its 11,500-year orbit, Sedna reaches a distance of 943 AU. 2003 UB313 now lies 97 AU from the Sun and has reached the farthest part of its orbit. It was picked up by astronomers of the Institute of Astrophysics in Andalusia as part of a survey of the outer solar system for new objects that they have been carrying out since 2002. | |||||
| The names Xena and Gabrielle |
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| UPDATE: 14.09.06 |
2003 UB313 (aka Xena) is now officially named (136199) Eris.
The moon, Gabrielle is now called Dysnomia. Following the Aug. 24 resolution by the IAU to the effect that the solar system contains eight "planets" (Mercury- Neptune), with (1) Ceres, Pluto (cf. IAUC 255), and 2003 UB313 (cf. IAUC 8577) to be considered representative "dwarf planets", the Minor Planet Centre included Pluto and 2003 UB313 (along with two other new potential dwarf-planet candidates) in the standard catalogue of numbered objects with well-determined orbits as (134340) and (136199), respectively (see MPC 57525). Following near-unanimous acceptance by both the Committee on Small-Body Nomenclature and the Working Group on Planetary-System Nomenclature (in consultation with the discovery team), the IAU Executive Committee has now approved the names Eris for (136199) and Dysnomia for its satellite (136199) Eris I (formerly S/2005 (2003 UB313) 1; cf. IAUC 8610).  to read more (PDF)
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| UPDATE: 12.08.05 | It seems that the Spitzer Space Telescope didn’t actually observe 2005UB313, due to a telescope pointing error. The "nondetection" was used by the astronomers to establish an upper size limit on the object. Follow-up observations are scheduled for late August. If Spitzer sees the object, it could mean that 2003 UB313 is much larger than the original limit of around 3,400 kilometres (2,100 miles). Hubble Space Telescope observations are also scheduled. (see update January 30 2006) Estimates now range from 2,390 km to 5,000 km or more. For Latest updates
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| Rotation period | The rotation period is perhaps 8 hours... | ||||
| Orbital elements: | 2003 UB313 Epoch 2005 Aug. 18.0 TT = JDT 2453600.5 MPC M 197.500556264619 (2000.0) P Q n 0.00176902 Peri. 151.336190564781 -0.91258509 -0.02028701 a 67.7091000 Node 35.8747311048078 -0.34877687 -0.48266077 e 0.4416129 Incl. 44.1774523927129 +0.21340843 -0.87557240 P 556.5673 H -1.0947 G 0.15 U 5 | ||||
| Persephone | |||||
| Three discoveries | 2003 EL61, 2003 UB313 (18.9 magnitude at 96 AU, and an H of -1.09) and 2005 FY9 (absolute magnitude H =0.1)
Quaoar, Orcus ( 2004 DW ), and Sedna have H values of 2.6, 2.3 and 1.6, respectively. For List of Transneptunian Objects
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| Ephemeris: | 2003 UB313 a,e,i = 67.71, 0.44, 44 q = 37.808 Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC APmag delta deldot S-O-T /r S-T-O 2006-Sep-29 00:00 01 38 32.13 -05 16 42.8 18.72 95.9153922136220 -7.3136027 159.1443 /L 0.2148 2006-Oct-04 00:00 01 38 21.55 -05 17 46.3 18.71 95.8977872196769 -4.8781912 162.3548 /L 0.1825 2006-Oct-09 00:00 01 38 10.69 -05 18 47.3 18.71 95.8872641165719 -2.4101668 164.6442 /L 0.1583 2006-Oct-14 00:00 01 37 59.64 -05 19 45.1 18.71 95.8839169487067 0.0918367 165.5533 /L 0.1472 2006-Oct-19 00:00 01 37 48.48 -05 20 39.3 18.71 95.8878319620420 2.6155314 164.8163 /L 0.1524 2006-Oct-24 00:00 01 37 37.30 -05 21 29.3 18.71 95.8990336664662 5.1335259 162.6292 /T 0.1724 2006-Oct-29 00:00 01 37 26.20 -05 22 14.5 18.72 95.9174604957974 7.6143232 159.4411 /T 0.2023 2006-Nov-03 00:00 01 37 15.26 -05 22 54.6 18.72 95.9429615849297 10.0296019 155.6364 /T 0.2377 2006-Nov-08 00:00 01 37 04.58 -05 23 29.0 18.73 95.9753284790076 12.3702516 151.4556 /T 0.2755 2006-Nov-13 00:00 01 36 54.24 -05 23 57.6 18.74 96.0143469095225 14.6345922 147.0362 /T 0.3140 2006-Nov-18 00:00 01 36 44.31 -05 24 19.8 18.74 96.0597681227423 16.8004751 142.4587 /T 0.3519 2006-Nov-23 00:00 01 36 34.89 -05 24 35.4 18.75 96.1112666413582 18.8390848 137.7728 /T 0.3884 2006-Nov-28 00:00 01 36 26.06 -05 24 44.2 18.76 96.1684323558404 20.7217209 133.0116 /T 0.4229
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 Image credit: Samuel Oschin Telescope, Palomar Observatory | |||||
| With the current temporary name 2003UB313, the KBO was discovered in an ongoing survey at Palomar Observatory's Samuel Oschin telescope by astronomers Mike Brown (Caltech), Chad Trujillo (Gemini Observatory), and David Rabinowitz ( Yale University). They have proposed a name to the IAU and will announce it when that name is accepted. (See update) ( Lilah Binney Brown is the name of Mike Brown's newborn daughter ... ) | |||||
| for image source For Latest Astronomy News
| Semi-major axis (a) 67.7091 AU Perihelion (q) 37.743783424709 AU Aphelion (Q) 97.57860345 AU Orbital period (P) 556.5673 y Mean orbital speed 3.436 km/s Inclination (i) 44.177° | ||||
| Another Planet discovered |
Dr. Michael Brown, associate professor of planetary astronomy, California Institute of Technology, Pasadena, California, presented his discovery and major findings of the most distant object ever detected orbiting the Sun, at a press media teleconference held on the 29 th July.
He and his colleagues made the observations as part of a NASA-funded research project.With the current temporary name 2003UB313, the KBO was discovered in an ongoing survey at Palomar Observatory's Samuel Oschin telescope by astronomers Mike Brown (Caltech), Chad Trujillo (Gemini Observatory), and David Rabinowitz ( Yale University). They have proposed a name (lila) to the IAU and will announce it when that name is accepted. And It is bigger than Pluto!!! | ||||
| A 14-inch scope, a CCD camera, and a dark site should be able to detect the new object. | |||||
This magnitude 18.9 object is at least the size of Pluto and likely a bit larger. The object, designated 2003 UB313, is currently 97 astronomical units away in the constellation Cetus — more than twice Pluto's average distance from the Sun.
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| 2003 UB313 |
is a scattered-disk object, meaning that at some point in its history Neptune likely flung it into its highly inclined (44°) orbit.
Like Pluto, its orbit is highly eccentric, and brings it to within 35AU of the Sun at its perihelion. Position(2000): RA 1h 39.3m, Dec –5° 21' to Read More
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| The Gemini Observatory |
has obtained a spectrum of 2003 UB313.
The observations were obtained on January 25, 2005 by Chad Trujillo, a Gemini staff member who is also on the discovery team for 2003 UB313, the existence of which was formally announced by the Minor Planet Centre in Cambridge, MA on July 29, 2005.
The research team obtained spectra of the surface of the object also using the NIRI (the near-infrared spectrograph) on the much larger 8 meter Gemini North telescope on Mauna Kea, Hawaii. The NIRI spectra show strong signatures of methane ice, remarkably similar to the spectrum of Pluto, which is also dominated by methane ice in near-infrared observations. "We still do not know much about this object, however, it is clear that it is very similar to Pluto in both size and composition, at least upon first glance. If 2003 UB313 ever got close to the sun, all the methane ice would have boiled off immediately. To date, no one has seen methane on any other Kuiper Belt Object, only on Pluto and Neptune's moon Triton." - Chad Trujillo. The presence of methane ice is unusual in that it indicates a primitive surface that has not likely been heated significantly since the solar system formed 4.5 billion years ago. The team have also obtained spectra of the smaller mini-planet 2003 EL61. The object shows strong water-ice features, similar to what is seen on the surface of Pluto's moon Charon. | ||||
| 30 August 2005 | Discovery of a planetary-sized object in the scattered Kuiper belt M.E. Brown1, C.A. Trujillo2, D.L. Rabinowitz3 We present the discovery and initial physical and dynamical characterization of the object 2003 UB313. The object is sufficiently bright that for all reasonable values of the albedo it is certain to be larger than Pluto. Pre-discovery observations back to 1989 are used to obtain an orbit with extremely small errors. The object is currently at aphelion in what appears to be a typical orbit for a scattered Kuiper belt object except that it is inclined by about 44 degrees from the ecliptic. The presence of such a large object at this extreme inclination suggests that high inclination Kuiper belt objects formed preferentially closer to the sun. Observations from Gemini Observatory show that the infrared spectrum is, like that of Pluto, dominated by the presence of frozen methane, though visible photometry shows that the object is almost neutral in colour compared to Pluto’s extremely red colour. 2003 UB313 is likely to undergo substantial seasonal change over the large range of heliocentric distances that it travels; Pluto at its current distance is likely to prove a useful analogy for better understanding the range of seasonal changes on this body. Since the discovery of the first small objects beyond Neptune astronomers have speculated about the existence of objects larger than Pluto in the Kuiper belt. Extrapolation of the size distribution of smaller Kuiper belt objects (KBOs) has sometimes been used to attempt to estimate the numbers of such larger objects (i.e. Bernstein et al. 2004), but such estimates have proven inconclusive. One of the goals of our ongoing survey for bright KBOs is to find the rare objects at the bright end of the Kuiper belt magnitude distribution. Such bright objects are invaluable as targets for detailed physical study in addition to being potential beacons of previously unknown populations. The newly discovered KBO 2003 UB313 is currently the fourth brightest object known in the Kuiper belt (after Pluto, 2003 FY9, and 2003 EL61) and is currently the most distant object ever seen in orbit around the sun. As an object notable for its brightness, distance, and size, 2003 UB313 is certain to be the object of intensive study. We present here details on its discovery, preliminary observations about its surface characteristics, and some suggestions about physical processes operating on this object.2003 UB313 was discovered in data from 21 October 2003 obtained from our ongoing survey at the 48-inch Samuel Oschin telescope at Palomar Observatory. At the time of discovery the object was moving 1.42 arc seconds per hour, slower than the cut-off in our main survey. Our survey obtains three images over a 3 hour period. With typical image quality of from 2 to 3 arc seconds, slower motions are clearly detectable, but we installed a 1.5 arc second per hour lower limit to our analysis to cut down the copious false positives at the slow end. The discovery of Sedna, with a motion of 1.75 arc seconds per hour, however, suggested a need to efficiently search for distant objects which would be moving at lower rates. We have now reanalysed all survey data with a second (”slow”) detection scheme in addition to the standard (”fast”) scheme. This slow scheme searches for motions between 1 and 2 arc seconds per hour between the first and third image of a triplet. When a potential object is found it checks for consistency using the second image, but motion need not be detected between either the first and second or second and third images. Finally, to remove the large number of false positives generated by stationary stars, all potential detections which are within 2 arc seconds of a catalogued USNO star are removed without examination. The slow scheme generates 10 to 20 times more false positives than the fast scheme, leading to approximately 1200 candidates every month. These candidates are examined by eye and are generally quickly rejected. On occasion we also make use of the Skymorph data base1 to determine that a potentially moving candidate is, in fact, a stationary star. In the two years worth of slow data examined to date we have found only two real objects: Sedna (previously also found in the fast scheme) and 2003 UB313. The extreme brightness and slow motion of 2003 UB313 made it easy to identify it as a transient in archival data. The object was identified in multiple images from the Skymorph data base and eventually found in a 1989 plate from the UK Schmidt telescope at Siding Springs Observatory. From this 16-year orbital arc the derived barycentric orbit using the method of Bernstein & Khushalani (2000) gives a semi-major axis, eccentricity, and inclination of a = 67.89±0.01, e = 0.4378±0.0001, and i = 43.993±0.001, respectively. 2003 UB is currently near aphelion at 97.50 ± 0.01 AU from the sun and will not reach perihelion at 38.2 AU until the year 2257. Based on the semi-major axis and eccentricity, 2003 UB313 would be classified as a typical member of the scattered Kuiper belt. The inclination of 44 degrees is extreme for the scattered belt, however. Only one other otherwise unremarkable scattered object (2004 DG77) has a confirmed orbit with an inclination as high. While initial models of the scattered Kuiper belt were incapable of populating high inclination regions, recent work suggests that a combination of gravitational scattering, mean-motion resonant interaction, planetary migration, and the Kozai mechanism may be able to place objects into orbits such as these. Additional simulations show that objects that are initially in the inner part of the pre-migration disk (at distances of 20 AU) are scattered into orbits with higher inclinations than those further out (Gomes 2003). We expect that, on average, these inner regions will lead to the formation of larger objects owing to both higher nebular densities and shorter accretion time scales. We might therefore expect to find other large objects at high inclination in the scattered Kuiper belt. Indeed, the other two recently announced scattered KBOs from our survey, 2005 FY9 and 2003 El61, both have inclinations near 30 degrees and approach the size of Pluto. 3. Spectrum Visible photometry of 2003 UB313 was obtained on 5, 6, and 7 January 2005 using the 1.3-meter SMARTS telescope. Data were obtained and reduced in an identical manner to that described in Rabinowitz et al. (2005). Infrared photometry was obtained on 25 and 26 January from the Gemini North Observatory. No evidence for any photometric variation (http://skys.gsfc.nasa.gov/skymorph/skymorph.html) was seen over the short time scale of observation. No attempt is made to correct for solar phase effects, which are of order 0.01 magnitudes at Pluto for a 0.5 degree phase. The relative brightness of 2003 UB313 is highest in the R and I filters. We find an absolute magnitude of Hr = -1.48, which corresponds to a diameter of 2250 -1/2 r km, where r is the R albedo. Even if the surface albedo is an unreasonably high 100% at these wavelengths the object has a diameter approximately that of Pluto. Medium resolution near-infrared spectra were obtained on the nights of 25-27 January UT with the Near Infrared Imager and Spectrograph instrument on the Gemini North telescope. The J, H and K bands were measured using 3 separate grating settings and on-source times of one, one, and two hours, respectively. Relative reflectance was computed by dividing the spectra by a solar analogy G2V star at a similar airmass to 2003 UB313. Each spectra was pair subtracted to remove detector bias, then flattened and rectified. Bad pixels and cosmic rays were masked out in each spectrum prior to extraction.
Extracted spectra were rebinned to a common wavelength scale with regions affected by bright OH lines masked out. Error bars were computed from the reproducibility of spectral data in each wavelength bin. Though 2003 UB313 is relatively bright, the signal-to-noise of the spectrum is only moderate owing to the fact that at the time of discovery the object was quickly setting in the evening sky. Figure 1 shows the relative reflectance of 2003 UB313, with the individual J, H, and K spectra scaled to match the near-infrared photometry and the relative near-infrared colours of Pluto. Because of uncertainties in spectral slope across the near-infrared, we do not regard the relative scaling between the three separate spectra to be reliable. The near-infrared spectrum is dominated by absorption from CH4 and closely resembles that of Pluto. At the current signal-to-noise and systematic reproducibility level, no reliable detection is made of any other species on 2003 UB313, including, notably, the 2.15 µm line of N2, the 1.58 µm line of CO, both detected on Pluto, and the 2.01 and 2.07 µm lines of CO2 detected on Triton. In many cases there are potentially detections of these lines, but most are in spectral regions contaminated by bright sky lines or variable sky absorptions and none should be believed without additional observation and confirmation.
One major difference between the spectrum of 2003 UB313 and that of Pluto is that the visible region of 2003 UB313 is considerably less red than that of Pluto. If red visible colours on icy bodies are interpreted as due to irradiated complex organics, the difference between Pluto and 2003 UB313 is surprising given the similarity of the methane spectra of the two bodies. A more subtle difference between the spectra is a slight shift of the positions of the methane absorption lines. On Pluto methane is a minor component dissolved as a solid solution inside of N2 ice. The isolation of the methane molecules leads to a slight but measurable energy shift in the spectrum. The four best measured methane lines on 2003 UB313, in contrast, appear much closer to the positions measured in the laboratory for pure methane than they do for methane incorporated into N2. 2003 UB313 is the largest known object in orbit beyond Neptune, and, like the second largest object, Pluto, its spectrum is dominated by absorption due to methane. Methane ices subjected to ion and UV radiation irreversibly break down and reassemble into more complex hydrocarbons, leading eventually to the formation of dark red tholins. The continued presence of abundant methane on 2003 UB313 suggests the need, as has been suggested for Pluto, for an interior source to replenish the methane. The presence of methane on 2003 UB313 as well as Pluto suggests that this process is ubiquitous in the outer solar system and that methane is not retained on smaller objects where escape rates are higher. The red colours and large spatial albedo variations of Pluto have been suggested to be due to distinct regions covered by these dark red tholins. At Pluto’s current heliocentric distance, dark regions absorb enough sunlight to become too warm for methane condensation, while the bright regions serve as methane cold traps, thus reinforcing any albedo contrast in existence. At the 97 AU distance of 2003 UB313, however, even dark regions will be sufficiently cold that as methane freezes out of the atmosphere or is replenished from the subsurface it will cover the entire body, lowering albedo contrasts and hiding the red tholins. This model leads to the prediction that 2003 UB313 will have significantly less albedo variation than Pluto and that its albedo will be as high or higher than Pluto. The lower temperature of 2003 UB313 may also explain the difference in the state of the methane. Expected subsolar surface temperatures of a 70% albedo body at 97 AU are 30 K. At this temperature the vapour pressure over pure N2 ice is 420 nbar, while the vapour pressure over pure methane ice is below a pbar. Unlike Pluto’s present state, methane on 2003 UB313 is currently essentially involatile and will not be mixed in the atmosphere with nitrogen. As 2003 UB313 moved towards aphelion over the past two centuries nitrogen and methane may have segregated, perhaps vertically. As 2003 UB313 moves back towards perihelion a more Pluto-like mixing may occur. The discovery of 2003 UB313 provides a new lower temperature laboratory for the study of many of the processes discussed for Pluto, including atmospheric freeze out and escape, ice chemistry, nitrogen phase transitions, and volatile mixing and transport. The temperature variation from perihelion of aphelion of 2003 UB313 is even more extreme than that on Pluto. Higher quality infrared spectra, which should be readily obtainable for this moderately bright object, will be a key component of future studies. to download source
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| Three discoveries | At magnitude 17.5, 2003 EL61 orbits 51 AU from the Sun, and has a diameter about 0.70 Pluto diameters but elongated. Its mass is 0.32 the mass of Pluto. The orbit is steeply inclined at 28 degrees to the solar plane. The Period is 285 years. It has a moon 1% of primary mass in 49-day orbit. Discoverer: Ortiz; Moon discovered by Mike Brown who had also discovered the primary but did not announce first. At magnitude 18.9, 2003 UB313 orbits 97 AU from the Sun. It is twice as big as Pluto. The orbit is inclined at 44 degrees to the solar plane. The period is 557 years. It is a very bright object, Like Pluto; the object's surface is believed to be predominantly methane. At its present distance the surface is chilled to just 30°C above absolute zero. The object was discovered by Mike Brown. News of the discovery was announced earlier than expected after hackers broke into Brown's website and stole news of it… (according to initial reports, though it now seems an unlikely story) That led him to announce the planet and a third object - temporarily designated 2005 FY9 by the Minor Planet Centre. 2005 FY9 orbits 52 AU from the Sun. 2005 FY9 is estimated to have an absolute magnitude of -0.4; with a Pluto-like albedo of 0.6 this would give it a diameter that is less than the diameter of Pluto (2000km). Its orbit is inclined at 29 degrees to the solar plane, and has a Period of 308 years. It was discovered by Mike Brown. | ||||
| UPDATE: 10.09.05 | The new Trans-Neptunian objects are being formally announced this week at a planetary conference in Cambridge, England. Bearing the extremely temporary names 'Xena,'(2003 UB313) 'Santa,' (2003 EL61) ( and 'Easterbunny,'(2005 FY9) the conference in Cambridge represents the first formal, scientific disclosure of the objects. "They're just weird, and it appears that they must have been thrown into their unusual positions by Neptune's gravity jolting them like a slingshot" - Michael E. Brown The three astronomers are Michael E. Brown of the California Institute of Technology, Chadwick A. Trujillo of the University of Hawaii and David Rabinovitz of Yale University. Trujillo and Rabinovitz are discussing their finds at a planetary conference this week in Cambridge, England, but Brown stayed home because he promised his wife he'd help care for their new baby. Informally, Brown's team named Xena after TV's Warrior Princess; Santa because it was discovered last Dec. 28, just after Christmas, and Easterbunny because it appeared just before Easter this year. The light-hearted names are unlikely to be recognized officially | ||||
| Gabrielle UPDATE: 02.10.05 |
The newly discovered Kuiper Belt object, 2003 UB313, has a moon.
The moon is 100 times fainter than Xena and orbits once every couple of weeks. It was spotted on September 10, 2005, with the Laser Guide Star Adaptive Optics system on the 10-meter Keck II telescope at the W.M. Keck Observatory in Hawaii by Michael E. Brown, professor of planetary astronomy, and his colleagues at Caltech, the Keck Observatory, Yale University, and the Gemini Observatory in Hawaii. A paper about the discovery was submitted on October 3 to Astrophysical Journal Letters. "Since the day we discovered Xena, the big question has been whether or not it has a moon. Having a moon is just inherently cool-and it is something that most self-respecting planets have, so it is good to see that this one does too" - Michael E. Brown. Brown estimates that the moon, nicknamed "Gabrielle"-after the fictional Xena's fictional sidekick-is at least one-tenth of the size of Xena, which is thought to be about 2700 km in diameter (Pluto is 2274 km), and may be around 250 km across. To know Gabrielle's size more precisely, the researchers need to know the moon's composition, which has not yet been determined. Most objects in the Kuiper Belt are about half rock and half water ice. Since a half-rock, half-ice surface reflects a fairly predictable amount of sunlight, a general estimate of the size of an object with that composition can be made. Very icy objects, however, reflect a lot more light, and so will appear brighter-and thus bigger-than similarly sized rocky objects. Further observations of the moon with the Hubble Space Telescope, planned for November and December, will allow Brown and his colleagues to pin down Gabrielle's exact orbit around Xena. With that data, they will be able to calculate Xena's mass. "A combination of the distance of the moon from the planet and the speed it goes around the planet tells you very precisely what the mass of the planet is. If the planet is very massive, the moon will go around very fast; if it is less massive, the moon will travel more slowly. It is the only way we could ever measure the mass of Xena-because it has a moon" - Michael E. Brown. | ||||
| The discovery |
was made possible by Keck II's recently commissioned Laser Guide Star Adaptive Optics system. Adaptive optics is a technique that removes the blurring of atmospheric turbulence, creating images as sharp as would be obtained from space-based telescopes.
The new laser guide star system allows researchers to create an artificial "star" by bouncing a laser beam off a layer of the atmosphere about 75 miles above the ground. Bright stars located near the object of interest are used as the reference point for the adaptive optics corrections. Since no bright stars are naturally found near Xena, adaptive optics imaging would have been impossible without the laser system. | ||||
| Eris 1 |
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| Gabrielle | , a moon of Xena, was discovered on September 10, 2005. The discovery was made using the Laser Guide Star Adaptive Optics (LGS AO) system at the W.M. Keck Observatory. Images were taken at infrared wavelengths (2.1 microns) using the NIRC2 imaging camera over a period of 40 minutes. | ||||
| The presence of satellites | to 3 of the 4 brightest Kuiper belt objects is inconsistent with the fraction of satellites in the Kuiper belt at large. This suggests a different formation mechanism for the largest KBO satellites. The satellites of 2003 EL61 and 2003 UB313, with fractional brightness of 5% and 2% of their primaries, respectively, are significantly fainter relative to their primaries than other known Kuiper belt object satellites, again pointing to possible differences in their origin. The four brightest known objects in the Kuiper belt, Pluto, 2005 FY9, 2003 EL61, and 2003 UB313, with V magnitudes of 14.0, 16.8, 17.5, and 18.8, respectively, were all observed with the Keck LGS AO system during engineering commissioning in 2005. The satellites of 2003 EL61 and 2003 UB313 are much fainter compared to their primaries than any other known satellites. Neither of these satellites appears likely to have formed from the process of dynamical-friction aided capture thought to have occurred for many smaller Kuiper belt objects as this process requires that small bodies drain energy from the larger bodies to aid the capture. For bodies as faint as these satellites, dynamical friction would be essentially inoperable. Numerical simulations of a collisional origin for the Pluto-Charon system have been explored in detail, and many of the potential system outcomes after an impact contain satellites with a relative sizes similar to the 2003 UB313 and 2003 EL61 satellites. The simulated formation of these smaller satellites differs from the simulated creation of the Pluto-Charon system in that the large size and angular momentum of Charon are best produced by intact formation following the impact, while smaller sized objects are formed in accretion disks similar to that thought to have formed the Moon after an impact on the Earth. Formation in a disk has been shown to lead to a more-rapidly spinning primary, which could also explain the unusually rapid rotation of 2003 EL61. Nothing is currently known about the rotation state 2003 UB313, but the small secondary to 2003 UB313 might suggest a similarly rapid rotator. to read more | ||||
| UPDATE:
January 30 2006 These findings are wrong! |
New measurements from the Hubble Space Telescope taken in December 2005 show that the surface of 2003 UB313 is brighter than previously thought its albedo being 0.92 (compared with roughly 0.60 for Pluto). This indicates that the 10th planet with a reflectivity of 92%, is roughly 1% larger than Pluto's assumed diameter of 2280 kilometres.. Because the surface seems so fresh, Brown speculates that the surface is regenerated by Geysers. For a whiteness comparison fresh snow on earth has a reflectivity of 90%. "Its reflectivity is much higher than expected. It does indicate a fresh, icy surface" - astronomer Alex Filippenko, University of California, Berkeley. | ||||
| UPDATE: February 01 2006 |
New observations of 2003 UB313, show it to have a diameter of some 3,000km ±300km; which is about 700km more than Pluto. The measurement was undertaken by a German team using the 30m Iram (Institut de RadioAstronomie Millimetrique) telescope at Pico Veleta in the Sierra Nevada mountains. | ||||
| UPDATE: April 11 2006 |
Title: Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope
Authors: M.E. Brown, E.L. Schaller, H.G. Roe, D.L. Rabinowitz, C.A. Trujillo We have used the Hubble Space Telescope to directly measure the angular size of the large Kuiper belt object 2003 UB313. By carefully calibrating the point spread function of a nearby field star, we measure the size of 2003 UB313 to be 34.3 ±1.4 milliarcseconds, corresponding to a diameter of 2400 ±100 km or a size ±5% larger than Pluto. The V band geometric albedo of 2003 UB313 is 86 ±7%. The extremely high albedo is consistent with the frosty methane spectrum, the lack of red colouring, and the lack of observed photometric variation on the surface of 2003 UB313. Methane photolysis should quickly darken the surface of 2003 UB313, but continuous evaporation and redeposition of surface ices appears capable of maintaining the extreme alebdo of this body. to Read more (PDF)
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| UPDATE: August 25 2006 |
About 2,500 experts are in Prague for the International Astronomical Union's (IAU) general assembly voted on the 24th August 2006 on a formal definition for the term "planet". The IAU has dropped its original plan to call Pluto and many more distant objects as planets. Instead, it has come up with another definition that would see the ninth planet airbrushed out of school and university textbooks. The IAU's final resolution on the definition of a planet adds an important change that states a planet must be the dominant object in its orbital zone, clearing out any smaller neighbours. The result would be a Solar System with eight "classical" planets; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Eris and similar objects would be now called Dwarf planets. | ||||
| Links: | For latest breaking news
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| wikipedia.org/wiki/2003_UB313 | |||||
| www.zanestein.com/Trans-pluto.htm | |||||
| Updated: | 29th September 2006 | 
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