1998 WW31

Binary Kuiper belt object February 2018 yes 1998 WW 31 #C2E0FF 2000 (1998 WW31) 1.jpg Hubble Space Telescope image of 1998 WW 31 and its satellite in orbit M. W. BuieR. L. Millis Kitt Peak Obs. 18 November 1998(first observed only) 1998 WW 31 TNOcubewano (hot)distantbinary 21 November 2025 (JD 2461000.5) 4 26.12 yr (9,540 d) 48.550 AU 41.339 AU 44.944 AU 0.08022 301.31 yr (110,054 d) 146.197° 0.003271 ms / day 6.7795° 237.019° 53.901° 1 (D: 123 km; P: 587 d) 148 km (est. primary)192.1 km (cal. system) 2.658 0.015 18 kg 0.04 (est.)0.10 (assumed) blueC (assumed)V–I 0.910 0.020 6.56.9 1998 WW 31 is a non-resonant trans-Neptunian object and binary system from the Kuiper belt located in the outermost region of the Solar System, approximately 148 km mi off 2 us in diameter. It was first observed on 18 November 1998, by American astronomer Marc Buie and Robert Millis at the Kitt Peak National Observatory in Arizona, United States. In December 2000, a minor-planet moon, designated S/2000 (1998 WW 31) 1 with a diameter of 123 km mi off 2 us, was discovered in its orbit. After Charon in 1978, it was the first of many satellites since discovered in the outer Solar System. Orbit and classification Located beyond the orbit of Neptune, 1998 WW 31 is a non-resonant classical Kuiper belt object (cubewano) of the so-called hot population, which have higher inclinations than those of the cold population. It orbits the Sun at a distance of 40.4–48.5 AU once every 297 years (108,345 days; semi-major axis of 44.48 AU). Its orbit has an eccentricity of 0.09 and an inclination of 7° with respect to the ecliptic. The body's observation arc begins at Kitt Peak with its first observation on 18 November 1998. Numbering and naming As of 2025, this minor planet has not been numbered nor named by the Minor Planet Center. Physical characteristics 1998 WW 31 is expected to have a low albedo due to its blue (neutral) color. Other sources assume a higher albedo of 0.10 and 0.16, respectively (see below). It has a V–I color index of 0.91, notably lower than the mean-color index for cubewanos, and in between that of comets and Jupiter trojans.35 Satellite thumb|left|Hubble image composite from 2001 to 2002 of 1998 WW 31 with its satellite on a long, 587-day orbit thumb|left|Hubble Space Telescope timelapse of 1998 WW 31's moon orbiting the parent body. On 22 December 2000, French astronomers Christian Veillet and Alain Doressoundiram in collaboration with J. Shapiro discovered that the observed body was a binary, using the Canada–France–Hawaii Telescope at Mauna Kea on the Big Island of Hawaii, United States. The discovery was announced on 16 April 2001, and the smaller body received the provisional designation S/2000 (1998 WW 31) 1. It was the first trans-Neptunian binary discovered after Charon in 1978, the largest satellite in the Pluto–Charon system. Since then, many trans-Neptunian binaries have been discovered. 1998 WW 31 is also one of the most symmetrical binaries known in the Solar System. The satellite has a highly eccentric orbit with an eccentricity of 0.8193 0.0020 with an exceptionally long orbital period of 587.27 0.18 days and a semi-major axis of 22,617 42 km. The discovery team concluded that, if the primary and secondary have the same albedo, their size ratio is 1.2, and if they also have the same densities, their mass ratio is 1.74 – that is, that the secondary has 60% the mass of the primary, or a bit over a third of the system mass. If they have equal densities of 1 g/cm3, that would mean nominal diameters of 148 km and 123 km, respectively, and albedos of 0.05~0.06. Diameter and albedo Assuming a density of 1 g/cm3, the primary measures 148 km, the satellite has a diameter of 123 km (a ratio of 0.883) with a combined system diameter of 192 km. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10 and calculates a system diameter of 192 km based on an absolute magnitude of 6.7, while Mike Brown finds a diameter of 267 km with a lower albedo of 0.04. Rotation period As of 2020, no rotational lightcurve of 1998 WW 31 has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown. References 30em 2011-12-24 last obs. JPL Small-Body Database Browser: (1998 WW31) https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=3031823 Jet Propulsion Laboratory 10 October 2018 1998 WW31 Minor Planet Center https://www.minorplanetcenter.net/db_search/show_object?object_id=1998+WW31 10 October 2018 List Of Transneptunian Objects Minor Planet Center https://minorplanetcenter.net/iau/lists/TNOs.html 10 October 2018 List of Known Trans-Neptunian Objects Johnston's Archive 30 December 2017 Johnston Wm. Robert http://www.johnstonsarchive.net/astro/tnoslist.html 10 October 2018 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 10 October 2018 Asteroid 1998 WW31 Small Bodies Data Ferret https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=1998+WW31 10 October 2018 10 October 2018 https://web.archive.org/web/20181010174459/https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=1998+WW31 dead Asteroids with Satellites Database – 1998 WW31 and S/2000 (1998 WW31) 1 Johnston's Archive 31 January 2015 Johnston, Wm. Robert http://www.johnstonsarchive.net/astro/astmoons/am1998ww31.html 10 October 2018 C. Veillet A. Doressoundiram J. Shapiro J. J. Kavelaars A. Morbidelli April 2001 S/2000 (1998 WW_31) 1 http://www.cbat.eps.harvard.edu/iauc/07600/07610.html#Item1 IAU Circ. 7610 1 2001IAUC.7610....1V 10 October 2018 The binary Kuiper-belt object 1998 WW31 Nature 18 April 2002 http://www.cfht.hawaii.edu/~veillet/Nature_final.pdf 10 October 2018 1998 WW31 10 October 2018 O. R. Hainaut H. Boehnhardt S. Protopapa October 2012 Colours of minor bodies in the outer solar system. II. A statistical analysis revisited Astronomy and Astrophysics 546 20 2012A&A...546A.115H 10.1051/0004-6361/201219566 1209.1896 54776793 6 S. Fornasier E. Dotto O. Hainaut F. Marzari H. Boehnhardt F. De Luise M. A. Barucci October 2007 Visible spectroscopic and photometric survey of Jupiter Trojans: Final results on dynamical families Icarus 190 2 622–642 2007Icar..190..622F 10.1016/j.icarus.2007.03.033 0704.0350 12844258 Grundy W.M. Noll K.S. Roe H.G. Buie M.W. Porter S.B. Parker A.H. Nesvorný D. Levison H.F. Benecchi S.D. Stephens D.C. Trujillo C.A. Mutual orbit orientations of transneptunian binaries Icarus December 2019 334 62–78 10.1016/j.icarus.2019.03.035 2019Icar..334...62G External links The binary Kuiper-belt object 1998 WW 31, publication in Nature, 18 April 2002 The binary Kuiper Belt Object 1998 WW31, Christian Veillet - CFHT - 17 April 2002 IAUC 7610: S/2000 (1998 WW_31) 1, satellite discovery – Central Bureau for Astronomical Telegrams, 16 April 2001 Orbit Fit and Astrometric record for 1998 WW31, Marc W. Buie, SwRI (Space Science Department) 1998 WW 31 and S/2000 (1998 WW 31) 1 MPEC 2008-O05 : Distant Minor Planets (2008 AUG. 2.0 TT) 1998WW31 3031823 # Category:Minor planet object articles (unnumbered) # 19981118