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Encyclopedia > 90482 Orcus
90482 Orcus
Discovery
Discovered by: M. Brown,
C. Trujillo,
D. Rabinowitz
Discovery date: February 17, 2004
Orbital characteristics
Epoch November 10, 1951 (JD 2433960.5)
Aphelion distance: 7226.801 Gm (48.31 AU)
Perihelion distance: 4567.091 Gm (30.53 AU)
Semi-major axis: 5896.946 Gm (39.419 AU)
Eccentricity: 0.22552
Orbital period: 90396.4 d (247.492 a)
Avg. orbital speed: 4.68 km/s
Mean anomaly: 79.561°
Inclination: 20.55233°
Longitude of ascending node: 268.586°
Argument of perihelion: 73.8325°
Satellites: 1 (92-432 km)
Physical characteristics
Dimensions: 946.3+74.1-72.3 km[1]
Mass: ~7.5×1020 kg
Mean density: ~1.5 g/cm³ (assumed)
Equatorial surface gravity: ~0.2 m/s²
Escape velocity: ~0.44 km/s
Rotation period: ? d
Albedo: 19.75+3.40-2.76 %
Temperature: ~45 K
Spectral type: B-V=0.68; V-R=0.37 [2]
Absolute magnitude: 2.3

90482 Orcus (originally known by the provisional designation 2004 DW) is a Kuiper Belt object (KBO) that was discovered by Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale University. The discovery images of this object were acquired on February 17, 2004. Precovery images as early as November 8, 1951 were later identified. Michael (Mike) E. Brown (born c. ... Chadwick A. Chad Trujillo (born November 22, 1973), is the co-discoverer of Eris, which he claims to be the Tenth Planet. ... This article or section does not cite its references or sources. ... February 17 is the 48th day of the year in the Gregorian calendar. ... shelby was here 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... m. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... November 10 is the 314th day of the year (315th in leap years) in the Gregorian calendar, with 51 days remaining. ... 1951 (MCMLI) was a common year starting on Monday; see its calendar. ... The Julian day or Julian day number (JDN) is the (integer) number of days that have elapsed since Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That day is counted as Julian day zero. ... A diagram of Keplerian orbital elements. ... A diagram of Keplerian orbital elements. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... Look up giga- in Wiktionary, the free dictionary. ... The or meter (see spelling differences) is a measure of length. ... The astronomical unit (AU or au or a. ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Look up day in Wiktionary, the free dictionary. ... In astronomy, a Julian year is a unit of time defined as exactly 365. ... The orbital speed of a body, generally a planet, a natural satellite, an artificial satellite, or a multiple star, is the speed at which it orbits around the barycenter of a system, usually around a more massive body. ... Look up second in Wiktionary, the free dictionary. ... In the study of orbital dynamics the mean anomaly is a measure of time, specific to the orbiting body p, which is a multiple of 2π radians at and only at periapsis. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... A degree (in full, a degree of arc, arc degree, or arcdegree), usually symbolized °, is a measurement of plane angle, representing 1/360 of a full rotation. ... The Longitude of the ascending node (☊, also noted Ω) is one of the orbital elements used to specify the orbit of an object in space. ... The argument of periapsis (ω) is the orbital element describing the angle between an orbiting bodys ascending node (the point where the body crosses the plane of reference from South to North) and its periapsis (the point of closest approach to the central body), measured in the orbital plane and... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Space Shuttle Atlantis launches on mission STS-71. ... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis. ... Albedo is the ratio of reflected to incident electromagnetic radiation power. ... Fig. ... The kelvin (symbol: K) is a unit increment of temperature and is one of the seven SI base units. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ... The provisional designation of comets and asteroids are similar to each other: they both follow a pattern set in 1925 by the Minor Planet Center of the IAU. Historical designations At first, astronomers strove to assign symbols to the minor planets: 1 Ceres a stylized sickle 2 Pallas a lozenge... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... Michael (Mike) E. Brown (born c. ... The California Institute of Technology (commonly referred to as Caltech)[1] is a private, coeducational university located in Pasadena, California, in the United States. ... Chadwick A. Chad Trujillo (born November 22, 1973), is the co-discoverer of Eris, which he claims to be the Tenth Planet. ... The Gemini Observatory is an astronomical observatory consisting of two 8-metre telescopes at different sites. ... This article or section does not cite its references or sources. ... “Yale” redirects here. ... February 17 is the 48th day of the year in the Gregorian calendar. ... shelby was here 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Precovery is a term used in astronomy that describes the process of finding the image of an object (usually a minor planet) in old archived images or photographic plates, for the purpose of calculating a more accurate orbit. ... November 8 is the 312th day of the year (313th in leap years) in the Gregorian calendar, with 53 days remaining. ... 1951 (MCMLI) was a common year starting on Monday; see its calendar. ...

Contents

Orbit

This diagram shows the orbits of Orcus (blue), Pluto (red) and Neptune (grey). The three objects are shown in the current positions (as of April 2006). The dates of their perihelia (q) and aphelia (Q) are also marked.
This diagram shows the orbits of Orcus (blue), Pluto (red) and Neptune (grey). The three objects are shown in the current positions (as of April 2006). The dates of their perihelia (q) and aphelia (Q) are also marked.

Orcus is a typical plutino (an object in 2:3 orbital resonance with Neptune). Orcus's 247 year orbit is shaped similarly to Pluto's (both have perihelia above the ecliptic), but is differently oriented. Although at one point its orbit approaches that of Neptune, the resonance between the two bodies means that Orcus itself is always a great distance away from Neptune (there is always an angular separation of over 60 degrees between them).
Image File history File links TheKuiperBelt_Orbits_Orcus2. ... Image File history File links TheKuiperBelt_Orbits_Orcus2. ... A diagram of Keplerian orbital elements. ... elements of an orbit. ... In astronomy, a plutino is a trans-Neptunian object that has a 3:2 orbital resonance with Neptune. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... Adjectives: Neptunian Atmosphere Surface pressure: ≫ 100 kPa (cloud level) Composition: 80% ± 3. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ... Adjectives: Neptunian Atmosphere Surface pressure: ≫ 100 kPa (cloud level) Composition: 80% ± 3. ... In mathematics (in particular geometry and trigonometry) and all natural sciences (including astronomy, geophysics, etc), the angular distance (or angular separation) between two point objects, as observed from a location different from either of these objects, is the size of the angle between the two directions originating from the observer...


Physical characteristics

Size and magnitude

The Earth Dysnomia (136199) Eris Charon (134340) Pluto (136472) 2005 FY9 (136108) 2003 EL61 (90377) Sedna (90482) Orcus (50000) Quaoar (20000) Varuna

Orcus compared to Eris, Pluto, (136472) 2005 FY9, (136108) 2003 EL61, Sedna, Varuna, Quaoar, and Earth.
Orcus compared to Eris, Pluto, (136472) 2005 FY9, (136108) 2003 EL61, Sedna, Varuna, Quaoar, and Earth.

The absolute magnitude of Orcus is 2.3 (comparable with the 2.6 of another KBO, 50000 Quaoar). In the first quarter of 2007 a paper was published, showing the Spitzer space telescope had detected Orcus in the far infrared, during its first three years in operation, constraining the size to 946.3+74.1-72.3 km.[1]. Orcus appears to have a high albedo of ~ 20 %. Image File history File links Download high-resolution version (2750x1995, 1859 KB) Summary Comparison of the eight largest TNOs, based on the public domain NASA image: Image:2006-16-d-print. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ... 50000 Quaoar (pronounced kwaa·waar or kwow·ər, English IPA: , Tongva ) [2] is a Trans-Neptunian object orbiting the Sun in the Kuiper belt. ... The Spitzer Space Telescope (formerly the Space Infrared Telescope Facility [SIRTF]) is an infrared space observatory, the fourth and final of NASAs Great Observatories. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... Orcus has several meanings: In mythology, Orcus is a god of the underworld, or a demon. ... Albedo is the ratio of reflected to incident electromagnetic radiation power. ...


Colours and spectra

Observations in infrared by the European Southern Observatory give results consistent with mixtures of water ice and carbonaceous compounds.[3] Further, the infrared spectra taken with the Gemini telescope confirmed a modest water ice signature, compatible with a cover of 15–30%, but no more than 50% of the surface. This means there is less ice than on Charon, but a similar amount to that on Triton. Limitations were also placed on the amount of methane ice (less than 30%) leaving open the possibility for discovery of other components in the future.[4] Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... The European Southern Observatory (ESO) is an international astronomical organisation, composed and supported by ten countries from the European Union plus Switzerland. ... Water Ice, sometimes referred to as Italian Water Ice, is a snack item served during the summer. ... This article belongs in one or more categories. ... Spectra are conditions or values that vary over a continuum. ... The Gemini Observatory is an astronomical observatory consisting of 8-metre telescopes at two different sites. ... Charon (shair-É™n or kair-É™n (key), IPA , Greek Χάρων), discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. ... Triton (trye-tÉ™n, IPA: , Greek Τρίτων), or Neptune I, is the planet Neptunes largest moon. ... Burning ice. Methane, released by heating, burns; water drips. ...


KBOs display a diversity of colours and spectra even among objects with similar orbits. Orcus presents a neutral colour in comparison with the redness of an object like Ixion. 28978 Ixion (IPA pronunciation: , Wiktionary:Ixion) is a Kuiper belt object discovered on May 22, 2001. ...


Satellite

The discovery of a satellite of Orcus was reported in IAUC 8812 on 22 February 2007 [1]. The orbit of this satellite has yet to be determined. February 22 is the 53rd day of the year in the Gregorian calendar. ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the CE era. ...


The satellite was found at 0.25 arcsec from Orcus with magnitude difference of 2.7[5]. Assuming an albedo similar to that of the primary the magnitude suggests a quite substantial diameter (~220 km) compared with Orcus. A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 ≈ 7. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ... Albedo is the ratio of reflected to incident electromagnetic radiation power. ...


Name

Under the guidelines of the International Astronomical Union's naming conventions, objects with a similar size and orbit to that of Pluto are named after underworld deities. Accordingly, the discoverers suggested naming the object after Orcus, a god of the dead in Roman mythology. The name was approved and published on November 22, 2004. Logo of the IAU The International Astronomical Union (French: Union astronomique internationale) unites national astronomical societies from around the world. ... In ancient times, only the Sun and Moon, a few hundred stars and the most easily visible planets had names. ... m. ... Adjectives: Plutonian Atmosphere Surface pressure: 0. ... // In the study of mythology and religion, the underworld is a generic term approximately equivalent to the lay term afterlife, referring to any place to which newly dead souls go. ... In Roman mythology, Orcus was a god of the underworld, punisher of broken oaths, more equivalent to Pluto than to the Greek Hades, and later identified with Dis Pater. ... A head of Minerva found in the ruins of the Roman baths in Bath Roman mythology, the mythological beliefs of the people of Ancient Rome, can be considered as having two parts. ... November 22 is the 326th day (327th on leap years) of the year in the Gregorian calendar. ... shelby was here 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ...


External links and sources

Kenneth J. Lawrence is an American astronomer. ... Daniel Joseph MacDonald, P.C (July 23, 1918 - September 30, 1980) was a Canadian politician. ... Eleanor Francis Helin is an American astronomer, principal investigator of the Near Earth Asteroid Tracking (NEAT) program of NASAs Jet Propulsion Laboratory. ... NEAT may stand for: Near Earth Asteroid Tracking NeuroEvolution by Augmented Topologies Neue Eisenbahn-Alpentransversale New England Actors Theater Non-Exercise Activity Thermogenesis Neat is also an archaic term for cattle. ...

References

  1. ^ a b Stansberry, J.; Grundy, W.; Brown, M.; et.al. (2007). "[http://arxiv.org/abs/astro-ph/0702538v1 Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope]". 
  2. ^ Tegler, Stephen C. (2006-01-26). Kuiper Belt Object Magnitudes and Surface Colors. Retrieved on 2006-11-05.
  3. ^ C. de Bergh, A. Delsanti, G. P. Tozzi, E. Dotto, A. Doressoundiram and M. A. Barucci (2005). "The Surface of the Transneptunian Object 9048 Orcus". Astronomy & Astrophysics 437: 1115-1120. DOI:10.1051/0004-6361:20042533. 
  4. ^ Chadwick A. Trujillo, Michael E. Brown, David L. Rabinowitz, Thomas R. Geballe (2005). "Near Infrared Surface Properties of the Two Intrinsically Brightest Minor Planets (90377) Sedna and (90482) Orcus". The Astrophysical Journal 627: 1057–1065. DOI:10.1086/430337.  Preprint on arXiv.
  5. ^ Distant EKO The Kuiper Belt Electronic newsletter, March 2007
Minor planets
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  Results from FactBites:
 
Orcus (minor planet 90482) (235 words)
The name Orcus, from a Roman god of the dead and another name for the Greek deity Hades, was approved by the International Astromical Union (IAU) on Nov. 22, 2004.
Orcus was discovered in images taken on Feb. 17, 2004 (nearly 74 years to the day after Pluto was found) by Mike Brown (CalTech), Chad Trujillo (Gemini Observatory), and David Rabinowitz (Yale) – the same team that discovered the largest known KBO, Eris (formerly called 2003 UB313).
The diameter of Orcus has been put at about 1,600 km (compared with Pluto's 2,300 km) but this is only an estimate because of uncertainty in the object's albedo (relectivity).
90482 Orcus (808 words)
Asteroid 90482, Orcus, a trans-Neptunian object, was discovered on February 17, 2004 by Chad Trujillo, Michael Brown and David Rabinowitz at Palomar Observatory near Pauma Valley, California.
Orcus was named for the Roman god of death, whom the Greeks called Thanatos and who is sometimes identified with Pluto.
Donald Trump has Orcus in the tenth house, conjunct the North Node, sextile Heracles (to contend with) and Deucalion, and opposite the Moon (the public), Lilith and the South Node.
  More results at FactBites »

 
 

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