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Sedna and trans neptunian objects

Sedna is a trans-Neptunian object discovered in 2003, which currently lies a couple of times as far from the Sun as Neptune. For most of the company’s orbit however, it can be even further from the Sun, which consists of aphelion estimated at 960 astronomical units (32 times Neptune’s distance); this is why it essential distant known objects while in the Solar System as apposed to long-period comets.

Though roughly two-thirds the dimensions of Pluto, its distance from the Sun makes determining its shape, for that reason demonstrating that must be in hydrostatic equilibrium, difficult. Spectroscopy has revealed that Sedna’s surface composition looks like that of one other trans-Neptunian objects, being largely a mixture of water, methane and nitrogen ices with tholins. Its surface considered reddest in the Solar System.

Sedna’s extremely long and elongated orbit, taking roughly 11,400 years to complete, and distant point of closest approach to the Sun, at 76 AU, have in order to much speculation as to its origin. The Minor Planet Center currently places Sedna while in the scattered disc, a set of two objects sent into highly extended orbits by the gravitational influence of Neptune. However, this classification continues to be contested, as Sedna never comes close enough to Neptune to have been scattered by it, leading some astronomers in the end that it can be in fact the first known member belonging to the inner Oort cloud. Others speculate that it was tugged into its current orbit by way of a passing star, perhaps one within the Sun’s birth cluster, as well as that it was captured from another star system. Another hypothesis suggests the reason is orbit could possibly be evidence for a large planet beyond the orbit of Neptune. Astronomer Michael E. Brown, co-discoverer of Sedna and the dwarf planets Eris, Haumea, and Makemake, believes so that it is by far the most scientifically important trans-Neptunian object found a long way, as understanding its unusual orbit in Your Own yield valuable information about the origin and early evolution of the Solar System.

Sedna (provisionally designated 2003 VB12) was discovered by Mike Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. The discovery formed part of a survey begun in 2001 aided by the Samuel Oschin telescope at Palomar Observatory near San Diego, California using Yale’s 160 megapixel Palomar Quest camera. Tomorrow, a physical object was observed to move by 4.6 arcseconds over 3.1 hours relative to stars, which indicated the reason is distance was about 100 AU. Follow-up observations in November-December 2003 along with the SMARTS telescope at Cerro Tololo Inter-American Observatory in Chile and aided by the Tenagra IV telescope at the W. M. Keck Observatory in Hawaii revealed that the object was moving along a distant highly eccentric orbit. Later the object was identified on older precovery images by means of the Samuel Oschin telescope as well as images from the Near Earth Asteroid Tracking consortium. These previous positions expanded its known orbital arc and allowed a more precise calculation of its orbit.

“Our newly discovered object could be the coldest most distant place known in the Solar System,” said Mike Brown on his website, “so we feel it really is appropriate to name it honoring Sedna, the Inuit goddess of the sea, who is thought to live in the bottom of the frigid Arctic Ocean.” Brown also suggested to the International Astronomical Union’s (IAU) Minor Planet Center that any future objects discovered in Sedna’s orbital region should also be named after entities in arctic mythologies. The group made the name “Sedna” public in front of the object had been officially numbered. Brian Marsden, the head of the Minor Planet Center, told me that such an action had been a violation of protocol, and that some members belonging to the IAU might vote against it. However, no objection was raised from what name itself, resulting in nil competing names were suggested. The IAU’s Committee on Small Body Nomenclature formally accepted the name in September 2004, and also considered that, in similar cases of extraordinary interest, it might in the future allow names to be announced before the pair were officially numbered.

Barring comets and a handful of Small Solar System Bodies, Sedna has got the longest orbital period of any known object while in the Solar System, calculated at around 11,400 years. Its orbit is extremely eccentric, with an aphelion estimated at 937 AU in addition to a perihelion at about 76 AU, probably the most distant perihelion ever observed for any Solar System object. At its discovery it was approaching perihelion at 89.6 AU from the Sun, called the most distant object while in the Solar System yet observed. Eris was later detected by the same survey at 97 AU. The big ten started orbits of some long-period comets extend farther compared to Sedna, they are too dim to always be discovered except when approaching perihelion while in the inner Solar System. Even as Sedna nears its perihelion in mid 2076, the Sun would appear merely as a very bright star in its sky, only 100 times brighter the actual usual full Moon that is known, and beyond the boundary away to always be visible as a disc to the naked eye.

Sedna has an absolute magnitude (H) of 1.6, is estimated to have albedo of 0.16 to 0.30, this provides you with it a diameter between 1,200 and 1,600 km. Throughout its discovery it was the most significant object perfectly found on the Solar System since Pluto in 1930. Mike Brown and colleagues now accept is as true to always be the fifth largest known trans-Neptunian object after Eris, Pluto, Makemake, and Haumea. In 2004, the discoverers placed an upper limit of a single,800 km on its diameter, but by 2007 this was revised downward to less than 1,600 km after observation by the Spitzer Space Telescope. As Sedna doesn’t have any known moons, determining its mass is a lot of work. However, if the above estimates because of its diameter are not to mention Pluto’s density of 2.0 g/cm3, the resulting predicted mass range is 1.8-4.3 x 1021 kg.

When first discovered, Sedna was thought to be have an unusually lengthy rotational period (20 to 50 days). It was initially speculated that Sedna’s rotation was slowed by the gravitational pull of a large binary companion, similar to Pluto’s moon Charon. A search for this kind of satellite by the Hubble Space Telescope in March 2004 found nothing, and subsequent measurements from the MMT telescope suggest a much shorter rotation period of about 10 hours; rather typical for a body of its size.

Experiences from the SMARTS telescope show that in visible light Sedna is among the reddest objects while in the Solar System, nearly as red as Mars. Chad Trujillo with the exceptional colleagues suggest that Sedna’s dark red colour is the effect of a surface coating of hydrocarbon sludge, or tholin, formed from simpler organic compounds after long in order to ultraviolet radiation. Its surface is homogeneous in colour and spectrum; this will likely be because Sedna, unlike objects nearer the Sun, is rarely impacted by other bodies, which would expose bright patches of fresh icy material like that on 8405 Asbolus. Sedna as well as 2 other very distant objects ((87269) 2000 OO67 and 2006 SQ372) share their colour with outer classical Kuiper belt objects as well as the centaur 5145 Pholus, suggesting a similar region of origin.

Trujillo and colleagues have placed upper limits in Sedna’s surface composition of 60% for methane ice and 70% for water ice. The methane further supports the inclusion of tholins on Sedna’s surface, as it is that is caused by irradiation of methane. Barucci and colleagues compared Sedna’s spectrum to be able of Triton and detected weak absorption bands belonging to methane and nitrogen ices. These types of observations, they suggested the following model of the surface: 24% Triton-type tholins, 7% amorphous carbon, 10% nitrogen, 26% methanol and 33% methane. The detection of methane and water ices was confirmed in 2006 by Spitzer Space Telescope mid-infrared photometry. The inclusion of nitrogen on the floor suggests the chance that, a minimum of for a short period of time, Sedna may possess an atmosphere. During a 200-year period near perihelion the maximum temperature on Sedna should exceed 35.6 K (-237.6