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From Planet X to Planet Nine

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From Planet X to Planet Nine From Planet X to Planet Nine Nuno Peixinho Café com Física 2016 The Triumph of Celestial Mechanics Neptune Finding Neptune • Neptune was teh first planet to be discoverd by prediction. • 1781, Anders Johan Lexell saw that there were irregularities in Uranus´ orbit. • 1846, Urbain Le Verrier predicted the mass and location for the unknown planet that would explain such irregularities. • Johann Gottfried Galle and Heinrich Louis d’Arrest find it at the Observatory of Berlin on the same day (at night, of coutrse) they received the news: September 23rd, 1846. • John Couch Adams also had predicted Neptune and he has credit for that but… “Planet-X” Planet O, P, Q, R, S, T, and U • William Pickering is the most prolific postulator of undiscoverd planets. • From 1908 to 1932, Pickering proposed seven hypothetical planets: O, P, Q, R, S, T and U. ⇒ Planet S Proposed in 1928; given elements in 1931: a=48.3 AU, P=336 yr, M=5M, mag=15. ⇒ Planet O Proposed in 1908; given elements in 1928: a=35.2 AU, P=209 yr, M=0.5M, mag=12. Planet X • Persival Lowell was searching for his Planet X. • During 1906, using a 5-inch (13 cm) camera. • From 1914 to 1916, a 9-inch (23 cm) telescope. ⇒ Planet X Proposed in 1906; given elements in 1927: a=43 AU, P=282 yr, M=6.6M, mag=12-13. • Never found anything but… Lowell Observatory did photograph Pluto in March and April 1915!!! • He founded the Lowell Observatory as private. Pluto • Clyde Tombaugh, a farm boy who was an amateur astronomer, was hired in 1929. • On January 23rd and 29th, 1930, he made teh exposures on which he found Pluto when examining them on February 18th. • The discovery was telegraphed on March 13th, 1930. • It was named Pluto by the 11 year old English girl Venetia Burney. Pluto • Clyde Tombaugh, a farm boy who was an amateur astronomer, was hired in 1929. • On January 23rd and 29th, 1930, he made teh exposures on which he found Pluto when examining them on February 18th. • The discovery was telegraphed on March 13th, 1930. • It was named Pluto by the 11 year old English girl Venetia Burney. Problems with Pluto I hate theoreticians! • Pluto was 6º off from the predictions. • Pluto was 10 times dimmer as predicted. • Pluto would not perturb other planets. • Pluto had a very elliptical orbit. • Pluto could not be Planet-X. • Pluto might not even be a planet at all! • Tombaugh continue his search for 13 more years. Charon • James Christy discovers Charon on June 22th, 1978. • The discovery is confirmed with plates from 1965 • 1/2 Pluto’s size, 1/8 Pluto’s mass. Pluto and Charon… in 2002 Pluto and Charon… in 2002 Other Moons • In 2005, Canup demonstrates that the Pluto-Charon system was formed by a collision. • In 2005, two other moons are discovered, and two more in 2011 and 2012: • Nix • Hydra • Kerberos • Styx • All were presumably formed by the collision, no captures are expected. New Horizons • Launched on January 19th, 2006. • Reached Pluto on July 14th, 2015. • In 2019… will reach 2014MU69. Better than a thousand words Charon Nix, Hydra, Kerberos, and Styx The Kuiper Belt Beyond Neptune • Leonard (1930), Edgeworth (1943, 1949) and Kuiper (1951) speculate on the existence of othe planets beyond Neptune or Pluto. • After several atempts by different teams in the 80s, Luu and Jewitt dicover the first Kuiper Belt Object (KBO) a.k.a. Trans-Neptunian Object (TNO): 1992QB1. (Oort and Kuiper) • Jan Oort (1900 – 1992) was famous for proposing the Oort cloud in 1950 — Ernst Öpik also proposed it in 1932. • Gerard Kuiper (1905 – 1973) suggested that comets may have formed in today’s Kuiper Belt but they should have been all sweapt away by now due to Pluto and Neptune. • Oort disagreed with him. Stubborn old man! Your ideas are rubbish. Kuiper Belt Objects or Trans-Neptunian Objets Some are big, but most are small Nix Namaka Hydra Styx Kerberos Haumea Hi’iaka Pluto Charon Makemake Weywot Quaoar Sedna Dysnomia Eris 1000 km Moon 3000 km Earth There are many dynamical families • Note: there is no strict definition for each family. 2:1 2:1 3:2 3:2 The 10th planet(s) and the end of Pluto • Since the discovery of KBOs that Pluto was in a bad situation. • November 14th, 2003, the “1st” 10th planet is announced: Sedna (2003VB12) ⇒ Now considered usually as a member of the Inner Oort Cloud. • July 27th, 2005, the “2nd” 10th planet is announced: Haumea (2003EL61) • July, 29th, 2005, the “3rd” 10th planet is announced: Eris (2003UB313) ⇒ The American started a war of accusations against the Spanish team. • First measurements indicated Eris was 50 km larger than Pluto, but soon after it was confirmed as being about 50 km smaller. Eris Eris Dysnomia Definition of Planet (1) A planet[1] is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit. (2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape[2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite. (3) All other objects[3], except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”. Footnotes: [1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. [2] An IAU process will be established to assign borderline objects into either dwarf planet and other categories. [3] These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies. Planet Nine • In 2008, Patryk Lykawka and Tadashi Mukai argue for the existence of a trans-Neptunian planet but they are not Americans… [ a = 100 – 175 AU, i = 20º– 40º, q > 80 AU, M = 0.3 – 0.7 M] • In 2014, Chad Trujillo and Scott S. Sheppard discuss the possible existence of a massive trans- Neptunian planet • In 2016, Konstantin Batygin and Mike E. Brown make a better argument for the existence of a massive trans-Neptunian planet, now nicknamed “planet nine”. P = 10 000 – 20 000 yr • The 8 m Subaru q = 200 AU telescope will be Q =1200 AU i = 30° used to attempt to detect it. Credits: JPL, Batygin and Brown/Caltech, A. Cuadra/Science How do we know? Giant Planets Migration • Best way to explain the orbital structure (Malhotra 1993) • Different populations are probably superimposed (Gomes 2003, ..., Levison et al. 2009). Credits: Levison & Morbidelli Implications PAST MIGRATION AND MIXING Ejection Contamination by comets? 5 AU 15 AU 30 AU 48 AU Mixing Exogenous water? PRESENTLY 5 AU Ejection 30 AU 48 AU NEOs Jupiter Neptune Asteroid belt Shooting Kuiper belt stars Centaurs Comets So… we simulate scenarios • We study the orbital distributions and try to reproduce them through simulations. Credits: Lykawka & Mukai (2008) So… we simulate scenarios • We study the orbital distributions and try to reproduce them through simulations. Credits: Lykawka & Mukai (2008) Planet Nine How do we know? • Distant orbits within the scattered disk population of the Kuiper belt exhibit an unexpected clustering in their respective arguments of perihelion. • The observed orbital alignment can be maintained by a distant eccentric planet with M>10 M⊕ , lying approximately in the same plane as those distant KBOS, but with perihelion 180 degrees away from the perihelia of the others. M > 10 M⊕ R = 2 – 4 R⊕ P = 10 000 – 20 000 yr q = 200 AU a = 600 AU Q =1200 AU i = 30° Credits: Nagualdesign - Own work, based on a video released by Caltech How do we know? • Distant orbits within the scattered disk population of the Kuiper belt exhibit an unexpected clustering in their respective arguments of perihelion. • The observed orbital alignment can be maintained by a distant eccentric planet with M>10 M⊕ , lying approximately in the same plane as those distant KBOS, but with perihelion 180 degrees away from the perihelia of the others. M > 10 M⊕ R = 2 – 4 R⊕ P = 10 000 – 20 000 yr q = 200 AU a = 600 AU Q =1200 AU i = 30° Credits: Nagualdesign - Own work, based on a video released by Caltech Oort Cloud Oort Cloud • In 1950, Oort argued for the existence of a far away “cloud”, around the solar system that should be the source of all comets (Öpik already had suggested it in 1932). • Made by the large number of objects ejected by the giant planets • The cloud should be ~10 000 and 100 000 AU (∼1 light-year). • Maybe there is an “inner Oort cloud” slightly decoupled from the rest (Sedna and 2012VP113 are there). • Nearby stars may push those objects so they become comets in the inner solar system. • Number of comets ∼ 1012 Oort Cloud • In 1950, Oort argued for the existence of a far away “cloud”, around the solar system that should be the source of all comets (Öpik already had suggested it in 1932). • Made by the large number of objects ejected by the giant planets • The cloud should be ~10 000 and 100 000 AU (∼1 light-year). • Maybe there is an “inner Oort cloud” slightly decoupled from the rest (Sedna and 2012VP113 are there). • Nearby stars may push those objects so they become comets in the inner solar system. • Number of comets ∼ 1012 Oort Cloud Thank you!.
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