2008 ST291

Last updated
2008 ST291
Discovery  [1]
Discovered by M. E. Schwamb
M. E. Brown
D. L. Rabinowitz
Discovery date September 24, 2008
Designations
MPC designation 2008 ST291
TNO (SDO) [2] [3]
6:1? [3]
Orbital characteristics   [4]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 4
Observation arc 3286 days (9.00 yr)
Aphelion 156.396  AU (23.3965  Tm)
Perihelion 42.271 AU (6.3237 Tm)
99.333 AU (14.8600 Tm)
Eccentricity 0.57445
990.04 yr (361611 d)
23.2101°
0.0009955°/day
Inclination 20.7849°
331.0475°
324.3727°
Physical characteristics
Dimensions 612 km (est. at 0.09) [5]
370–820 km (generic) [6]
22.3 [1] [7]
4.2 [4]

    2008 ST291, also written as 2008 ST291, is a trans-Neptunian object with an absolute magnitude of 4.2, [4] making it possibly a dwarf planet. [8] It is located near the 1:6 Neptune resonance of 99.4 AU (compared to its 99.3 ± 0.2 AU), meaning that it completes roughly 1 orbit for every 6 orbits Neptune makes. [3]

    Trans-Neptunian object any object in the Solar System that orbits the Sun at a greater average distance than Neptune

    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).

    Absolute magnitude is a measure of the luminosity of a celestial object, on a logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs, with no extinction of its light due to absorption by interstellar dust particles. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared on a magnitude scale. As with all astronomical magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified filter bands or passbands; for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum. Absolute magnitudes are denoted by a capital M, with a subscript representing the filter band used for measurement, such as MV for absolute magnitude in the V band.

    In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object (TNO) in mean-motion orbital resonance with Neptune. The orbital periods of the resonant objects are in a simple integer relations with the period of Neptune e.g. 1:2, 2:3 etc. Resonant TNOs can be either part of the main Kuiper belt population, or the more distant scattered disc population.

    Contents

    Size estimate

    2008 ST291 is estimated to be about 612 kilometres (380 mi) in diameter, assuming a typical albedo of 0.09 for trans-Neptunian objects. [5] However, because its albedo is unknown and it has an absolute magnitude of 4.2, [4] it could be anywhere between 370 and 820 km in diameter. [6]

    Distance

    Orbit comparison of 2008 ST291, Pluto and Neptune 2008ST291-orbit.png
    Orbit comparison of 2008 ST291, Pluto and Neptune

    2008 ST291, currently 60.9  AU from the Sun, [7] came to perihelion in 1954. [4] It takes almost one thousand years to orbit the Sun.

    Astronomical unit mean distance between Earth and the Sun, common length reference in astronomy

    The astronomical unit is a unit of length, roughly the distance from Earth to the Sun. However, that distance varies as Earth orbits the Sun, from a maximum (aphelion) to a minimum (perihelion) and back again once a year. Originally conceived as the average of Earth's aphelion and perihelion, since 2012 it has been defined as exactly 149597870700 metres or about 150 million kilometres. The astronomical unit is used primarily for measuring distances within the Solar System or around other stars. It is also a fundamental component in the definition of another unit of astronomical length, the parsec.

    Sun Star at the centre of the Solar System

    The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, or 109 times that of Earth, and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System. Roughly three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.

    Apsis extreme point in an objects orbit

    The term apsis refers to an extreme point in the orbit of an object. It denotes either the points on the orbit, or the respective distance of the bodies. The word comes via Latin from Greek, there denoting a whole orbit, and is cognate with apse. Except for the theoretical possibility of one common circular orbit for two bodies of equal mass at diametral positions, there are two apsides for any elliptic orbit, named with the prefixes peri- and ap-/apo- added to a reference to the body being orbited. All periodic orbits are, according to Newton's Laws of motion, ellipses: either the two individual ellipses of both bodies, with the center of mass of this two-body system at the one common focus of the ellipses, or the orbital ellipses, with one body taken as fixed at one focus, and the other body orbiting this focus. All these ellipses share a straight line, the line of apsides, that contains their major axes, the foci, and the vertices, and thus also the periapsis and the apoapsis. The major axis of the orbital ellipse is the distance of the apsides, when taken as points on the orbit, or their sum, when taken as distances.

    2008 ST291 has only been observed 28 times over four oppositions and has an orbit quality of 4 (0 being best; 9 being worst). [4]

    Opposition (planets) two celestial bodies are said to be in opposition when they are on opposite sides of the sky, viewed from a given place (usually Earth)

    In positional astronomy, two astronomical objects are said to be in opposition when they are on opposite sides of the celestial sphere, as observed from a given body.

    See also

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    References

    1. 1 2 "MPEC 2009-V68 : 2008 ST291". IAU Minor Planet Center. 2009-11-14. Retrieved 2009-12-06.
    2. ↑ "List Of Centaurs and Scattered-Disk Objects". Minor Planet Center . Retrieved 2009-12-06.
    3. 1 2 3 Marc W. Buie. "Orbit Fit and Astrometric record for 08ST291" (last observation: 2010-10-09 using 20 of 23 observations over 2.04 years). SwRI (Space Science Department). Retrieved 2009-12-06.
    4. 1 2 3 4 5 6 "JPL Small-Body Database Browser: (2008 ST291)" (last observation: 2017-09-23; arc: 9.00 years). Retrieved 31 July 2018.
    5. 1 2 Dan Bruton. "Conversion of Absolute Magnitude to Diameter for Minor Planets". Department of Physics & Astronomy (Stephen F. Austin State University). Archived from the original on 10 December 2008. Retrieved 2008-12-09.
    6. 1 2 "Absolute Magnitude (H)". NASA/JPL. Archived from the original on 26 November 2009. Retrieved 2009-12-06.
    7. 1 2 "AstDyS 2008 ST291 Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 31 July 2018.
    8. ↑ "How many dwarf planets are there in the outer solar system?". Gps.caltech.edu. 2015-07-21. Retrieved 20 September 2016.
    9. 1 2 "AstDyS-2, Asteroids - Dynamic Site" . Retrieved 2018-04-03. Objects with distance from Sun over 59 AU

    The JPL Small-Body Database (SBDB) is an astronomy database about small Solar System bodies. It is maintained by Jet Propulsion Laboratory (JPL) and NASA and provides data for all known asteroids and several comets, including orbital parameters and diagrams, physical diagrams, and lists of publications related to the small body. The database is updated on a daily basis.

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