(528381) 2008 ST291

Trans-Neptunian object May 2019 yes (528381) 2008 ST 291 #C2E0FF 2008 ST291-orbit.png Orbit of (528381) 2008 ST 291 M. E. SchwambM. E. BrownD. L. Rabinowitz Palomar Obs. 24 September 2008 (528381) 2008 ST 291 TNOSDOres 1:6 27 April 2019 (JD 2458600.5) 3 9.27 yr (3,385 d) 157.437 AU Tm on 42.3114440 AU Tm on 99.8742972 AU Tm on 0.5763530 998.30 yr (364,629 d) 23.349° 0.0010 ms / day 20.758° 330.97° 324.65° 0 549 km (est.)536 km (est.)612 kmBased on AstDyS magnitude and same 0.09 albedo as Brown using Bruton formula345 - 773 kmBased on averaged magnitude of 4.433 and typically assumed minor planet albedo range of 0.05 ~ 0.25, using Bruton formula 0.09 (assumed) 0.126 (assumed) 22.24 4.224.34.6 (528381) 2008 ST 291 is a 1:6 resonant trans-Neptunian object located in the outermost region of the Solar System that takes almost a thousand years to complete an orbit around the Sun. It was discovered on 24 September 2008 by American astronomers Megan Schwamb, Michael Brown and David Rabinowitz at the Palomar Observatory in California, with no known earlier precovery images. Numbering and naming This minor planet was numbered by the Minor Planet Center on 18 May 2019 (M.P.C. 114657). As of 2025, it has not been named. Orbit and classification thumb|left|Orbit comparison of 2008 ST 291, Pluto and Neptune 2008 ST 291 is located at the 1:6 Neptune resonance of 99 AU meaning that it completes roughly 1 orbit for every 6 orbits Neptune makes. It orbits the Sun at a distance of 42.3–157.5 AU once every 998 years and 4 months (semi-major axis of 99.89 AU). Its orbit has an eccentricity of 0.58 and an inclination of 21° with respect to the ecliptic. Currently located at 60.9 AU from the Sun, 2008 ST 291 came to perihelion in 1954. Physical characteristics Based on an absolute magnitude of 4.4, 2008 ST 291 is estimated by Johnston's Archive to be about 536 km mi in diameter, assuming a typical albedo of 0.126 for other Neptune resonant objects. Astronomer Mike Brown estimates a slightly bigger 549 km mi km using a albedo of 0.09 and a fainter 4.6 magnitude. The Asteroid Dynamic Site records a brighter 4.3 magnitude, which calculates to 612 km mi using the same albedo (and same formula as brown); using the average of these magnitudes and a standard assumed minor planet albedo range of 0.25 ~ 0.05, possible sizes of 345 - 773 km mi are produced. See also List of trans-Neptunian objects Notes References 2017-12-31 last obs. JPL Small-Body Database Browser: (2008 ST291) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3476640 Jet Propulsion Laboratory 29 May 2019 (528381) 2008 ST291 Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=2008+ST291 29 May 2019 MPC/MPO/MPS Archive Minor Planet Center https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html 29 May 2019 MPEC 2009-V68 : 2008 ST291 Minor Planet Center 14 November 2009 https://minorplanetcenter.net//mpec/K09/K09V68.html 29 May 2019 2008 ST291 – Ephemerides AstDyS-2, Asteroids – Dynamic Site https://newton.spacedys.com/astdys/index.php?pc=1.1.3.0&n=2008ST291 19 August 2019 List of Known Trans-Neptunian Objects Johnston's Archive 25 May 2019 Johnston Wm. Robert http://www.johnstonsarchive.net/astro/tnoslist.html 29 May 2019 How many dwarf planets are there in the outer solar system? California Institute of Technology Brown Michael E. http://web.gps.caltech.edu/~mbrown/dps.html 29 May 2019 Dan Bruton Conversion of Absolute Magnitude to Diameter for Minor Planets http://www.physics.sfasu.edu/astro/asteroids/sizemagnitude.html Stephen F. Austin State University, College of Sciences and Mathematics, Department of Physics, Engineering and Astronomy 15 August 2019 https://web.archive.org/web/20110723191750/http://www.physics.sfasu.edu/astro/asteroids/sizemagnitude.html 23 July 2011 External links Orbit Fit and Astrometric record for 528381, Marc W. Buie, SwRI List Of Centaurs and Scattered-Disk Objects, Minor Planet Center 2008ST291 3476640 528381 (528381) 2008 ST 291 528381 528381 Category:Discoveries by Megan E. Schwamb Category:Discoveries by Michael E. Brown Category:Discoveries by David L. Rabinowitz 20080924