Transcript astro_talk_100605

Unexpected planets beyond Pluto
their discovery, physical properties, and implications
for solar system history
David Rabinowitz
Yale University, Center for Astronomy and Astrophysics
Yale:
Charles Baltay, Nancy Ellman, Will Emmet,
Tom Hurteau, Rochelle Lauer, Suzanne Tourtellote
Indiana University:
Jim Musser, Brice Adams, Mark Gebhard
Caltech:
Michael E. Brown, Kristina Barkume, Henry Roe,
A.H. Bouchez, R. Sari, M. van Dam, R. Campbell,
J. Chin, S. Hartman, E. Johansson, R. Lafon,
D. LeMignant, P. Stomski, D. Summers, P. Wizinowich
Gemini Observatory :
Chad Trujillo
Sedna
2005 FY9
“Easter Bunny”
2003 EL61
“Santa”
Orcus
Quaoar
Pluto
(2200 km)
2003 UB313
“Xena”
120
Sedna
80
40
y (AU)
Xena
Bunny
0
-120
-80
-40
0
40
Santa
-40
-80
Saturn
Uranus
Neptune
-120
x (AU)
80
120
120
80
Saturn
Uranus
Neptune
40
Bunny
ecliptic plane
z (AU)
Santa
0
-120
-80
-40
0
-40
-80
-120
x (AU)
40
Sedna
80
120
Xena
Uranus
Herschel,
1781, 6”
“Xena”
Pluto
2005, 48”
Tombaugh,
1930, 13”
Sedna
2004, 48”
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Kuiper Belt
Jewitt, Luu
1992, 86”
Neptune
Le Verrier, Galle
1846, 9”
Beta Pictoris
AU Mic
H-band imaging with Keck Adaptive Optics (0.04” seeing)
M. Liu, Science 303, 2004
Where did the mass go ?
(0.1 earth mass)
Clyde Tombaugh - 1938
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The reflectance spectrum of 2003 UB313
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Possible Sizes for “Xena”
Type of
Surface
Albedo
Diameter
Pluto
Diameters
Fresh snow
90%
2330 km
1.0
Pluto
60%
2860 km
1.3
Charon
(Pluto’s moon)
38%
3550 km
1.5
Most Kuiper
Belt Objects
15%
5700 km
2.4
Keck discovery of Xena’s moon, “Gabrielle”
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Keck Laser Guide Star Observations
Easter Bunny
Charon
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Rudolph
Xena
Gabrielle
Santa
Xena-Gabrielle to Earth-moon
Moon
Earth
Xena
Xena
Gabrielle
Gabrielle
Santa (2003 EL61)
a squashed planet
Satellite Discovered around 2003 EL61 (“Santa”)
“Santa”
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“Rudolph”
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Rudolph’s orbit
Radius: 49,000 km
Period: 49 days
v2/r = MG/r2
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M = 4.21x1021 kg