2006 SQ372: A Planetary Interloper from the Inner Oort Cloud

N. Kaib, A. Becker, L. Jones

University of Washington

25000 AU• LPCs near Earth only constrain outer Oort Cloud

• LPCs beyond Saturn will sample inner Oort Cloud as well

LPCs and Oort Cloud

a > 20,000 AUa > 1,000 AU~

SDSS-II SN Survey Observations2006 SQ372

SDSS-II SN Survey Observations2006 SQ372

SDSS-II SN Survey Observations2006 SQ372

SDSS-II SN Survey Observations2006 SQ372

Orbit Summary

a = 796 AU q = 24.2 AU i = 19.5°

Orbital Evolution

Current orbit is transient - unstable after ~200 Myrs!

Two Different Origin Scenarios1. Scattered Disk

sem

imaj

or

axis

perihelion

x

Two Different Origin Scenarios2. Oort Cloud

sem

imaj

or

axis

perihelion

x

OC

SD

Simulations

Scattered Disk

• 2,500 particles

• Orbit distributions based on SDO observations

• Run for 4.5 Gyrs

Oort Cloud

• 106 particles

• Orbit distributions based on Kaib & Quinn (2008) sims

• Run for 1.4 Gyrs

Non-symplectic variable timestep integrator based on SWIFT (Levison & Duncan, 1994; Kaib & Quinn, 2008)

Results – OC Sim. (10° < i < 30°)

Fractional Occupation Map

X2006 SQ372

10° < i < 30°

fOC/fSD Map

SQ372

For 2006 SQ372: fOC/fSD 0.7

Origin Implications

ProbOC/ProbSD = (fOC/fSD) x (NOC/NSD)

fOC/fSD 0.7

NOC = 2 x 1011 (Neslusan, 2007)

NSD = 4 x 109 (Fernandez, 2004)

ProbOC/ProbSD > 35~

Origin Implications

• 2006 SQ372 is at least 35 times more likely to come from the Oort Cloud compared to the Scattered Disk

• Which region of the Oort Cloud?

Inner Oort Cloud Origin

Semimajor axis drawdown time

vs.

Perihelion drift time

q = -10 AU Ejection by Saturnq = 10 AU a is fixed

Inner Oort Cloud Origin

tq ~ a-2

ta ~ 100 Myrs

Sampled by Known LPCs

(~2.5%)

a < 800 AU20 AU < q < 30 AU

Conclusions

• 2006 SQ372 and 2000 OO67 (Elliot et al. 2005) are first detected members of inner Oort Cloud population inside planetary region

• Pan-STARRS, LSST will discover 100’s to 1000’s of similar bodies

• Population statistics can provide clues about Oort Cloud and Sun’s dynamical history

20

SDSS Stripe 82 N S

RA = 20 hr 120° RA = 4hr

D = +1.25°

D = -1.25°

2

.5°

SDSS Supernova Survey

• Sept-Nov 2005-2007• 300 square degrees, every 2 nights• 5-band photometry• Spectroscopic followup

Nov 2006; Single Epoch

Nov 2006; Quadratic Links

Nov 2006; Verified by Orbit Fitting

2006 SQ372

• 1 of 63 TNOs observed by SDSS-II SN Survey

• Diameter < 100 km

• Orbit:– q: 24.2 AU (between Uranus and Neptune)– a: 796 AU (largest of all TNOs)– i: 20°

Results (10° < i < 30°)

Results (10° < i < 30°)

Results (10° < i < 30°)

Results (10° < i < 30°)