174567 Varda (provisional designation ) is a binary

trans-Neptunian A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has a semi-major axis of 30.1 astronomical units (au). Typically, ...

planetoid of the resonant

hot classical A classical Kuiper belt object, also called a cubewano ( "QB1-o"), is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axe ...

population of the

Kuiper belt The Kuiper belt () is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

, located in the outermost region of the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

. Its

moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

, Ilmarë, was discovered in 2009. Michael Brown estimates that, with an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 3.5 and a calculated diameter of approximately , it is likely a dwarf planet. However, William M. Grundy ''et al.'' argue that objects in the size range of 400–1000 km, with albedos less than ≈0.2 and densities of ≈1.2 g/cm³ or less, have likely never compressed into fully solid bodies, let alone differentiated, and so are highly unlikely to be dwarf planets.W.M. Grundy, K.S. Noll, M.W. Buie, S.D. Benecchi, D. Ragozzine & H.G. Roe, 'The Mutual Orbit, Mass, and Density of Transneptunian Binary Gǃkúnǁʼhòmdímà ()', ''Icarus'
(forthcoming, available online 30 March 2019)
DOI: 10.1016/j.icarus.2018.12.037, It is not clear if Varda has a low or a high density.

Discovery and orbit

Varda was discovered in March 2006, using imagery dated from 21 June 2003 by Jeffrey A. Larsen with the

Spacewatch The Spacewatch Project is an astronomical survey that specializes in the study of minor planets, including various types of asteroids and comets at University of Arizona telescopes on Kitt Peak near Tucson, Arizona, in the United States. The Sp ...

telescope as part of a United States Naval Academy Trident Scholar project. It orbits the Sun at a distance of 39.5–52.7 AU once every 313.1 years (over 114,000 days;

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

of 46.1 AU). Its orbit has an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

of 0.14 and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 21.5 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic again ...

. , Varda is 47.5 AU from the Sun. It will come to

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

around November 2096. It has been observed 321 times over 23

oppositions ''Oppositions'' was an architectural journal produced by the Institute for Architecture and Urban Studies from 1973 to 1984. Many of its articles contributed to advancing architectural theory and many of its contributors became distinguished practi ...

, with

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

images back to 1980.

Name

Names for Varda and its moon were announced on 16 January 2014.

Varda Varda may refer to: People * Agnès Varda (1928–2019), French film director and professor *Jean Varda (1893–1971), Greek artist * Ratko Varda (born 1979), Bosnian basketball player *Rosalie Varda (born 1958), French costume designer, produce ...

() is the queen of the Valar, creator of the stars, one of most powerful servants of almighty

Eru Ilúvatar The cosmology of J. R. R. Tolkien's legendarium combines aspects of Christian theology and metaphysics with pre-modern cosmological concepts in the flat Earth paradigm, along with the modern spherical Earth view of the Solar System. The created ...

in J. R. R. Tolkien's fictional mythology. Ilmarë is a chief of the Maiar and Varda's handmaiden.

Planetary symbol A planet symbol (or ''planetary symbol'') is a graphical symbol used in astrology and astronomy to represent a classical planet (including the Sun and the Moon) or one of the modern planets. The symbols were also used in alchemy to represent the me ...

s are no longer much used in astronomy, so Varda never received a symbol in the astronomical literature. There is no standard symbol for Varda used by astrologers either. Zane Stein proposed a gleaming star as the symbol ( Varda symbol (fixed width)

Satellite

Varda has at least one

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

, Ilmarë (or Varda I), which was discovered in 2009. It is estimated to be about 350 km in diameter (about 50% that of its primary), constituting 8% of the system mass, or , assuming its density and albedo the same as that of Varda. The Varda–Ilmarë system is tightly bound, with a semimajor axis of (about 12 Varda radii) and an orbital period of 5.75 days.

Physical properties

Based on its apparent brightness and assumed albedo, the estimated combined size of the Varda–Ilmarë system is , with the size of the primary estimated at . The total mass of the

binary system A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter ''(also see animated examples)''. More restrictive definitions require that thi ...

is approximately . The density of both the primary and the satellite is estimated at about assuming that they have equal density. On the other hand, if the density or albedo of the satellite is lower than that of primary then the density of Varda will be higher up to . On 10 September 2018, Varda's projected diameter was measured to be via a stellar occultation, with a projected oblateness of . The equivalent diameter is 740 km, consistent with previous measurements. Given Varda's equivalent diameter derived from the occultation, its geometric albedo is measured at 0.099, making it as dark as the large

plutino In astronomy, the plutinos are a dynamical group of trans-Neptunian objects that orbit in 2:3 mean-motion resonance with Neptune. This means that for every two orbits a plutino makes, Neptune orbits three times. The dwarf planet Pluto is the lar ...

. The large uncertainty in Varda's rotation period yields various solutions for its density and true oblateness; given a rotation period of 5.91 or 11.82 hours, its bulk density and true oblateness could be either and 0.235 or and 0.080, respectively. The surfaces of both the primary and the satellite appear to be red in the visible and near-infrared parts of the spectrum (spectral class IR), with Ilmarë being slightly redder than Varda. The spectrum of the system does not show water absorption but shows evidence of

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...

ice. The rotation period of Varda is estimated at 5.61 hours.

Notes

References

External links

List of binary asteroids and TNOs
Robert Johnston, johnstonsarchive.net
LCDB Data for (174567) Varda
''Collaborative Asteroid Lightcurve Link''

* * {{DEFAULTSORT:Varda 174567 Discoveries by Jeffrey A. Larsen Named minor planets Binary trans-Neptunian objects 174567 174567 Astronomical objects discovered in 2003 Things named after Tolkien works