Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.stsci.edu/~mutchler/talks/Pluto_WAS.pdf Äàòà èçìåíåíèÿ: Wed Feb 8 20:48:57 2006 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 12:05:56 2012 Êîäèðîâêà:

The discovery of two new moons of Pluto

Hubble Pluto Satellite Search Team
reporting the discovery to the New Horizons Science Team on November 2, 2005 at the Kennedy Space Center
Andrew Steffl (SwRI) Marc Buie (Lowell Observatory) Eliot Young (SwRI)

Max Mutchler
Space Telescope Science Institute

Westminster Astronomical Society 8 February 2006 Hal Weaver (JHU/APL)

S. Alan Stern (SwRI)

Leslie Young (SwRI)

John Spencer (SwRI)

Bill Merline (SwRI)

Max Mutchler (STScI)

"The first discovery of the New Horizons mission"

Overview
· · · · · · · · · · Discovery of Pluto, Charon, and the Kuiper Belt Early Hubble observations of Pluto Hubble's Advanced Camera for Surveys Hubble mission support for New Horizons: discovery of two more Pluto satellites Confirming and following-up the discovery Implications, and related discoveries...what is a planet? New Horizons mission to Pluto: launched 19 Jan 2006! More information via the web My hometown astronomy club Questions? Names for the new moons?

The discovery of Pluto in 1930, and confirmation

Clyde Tombaugh

Discovery of the Kuiper Belt in 1992
The discovery of Pluto's moon Charon in 1978

James Christy & Robert Harrington U.S. Naval Observatory Washington, D.C.

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Discovery of two new moons of Pluto

Early Hubble observations of Pluto and Charon

Press release image for new moons: the discovery was surprisingly easy for Hubble with ACS... but not quite as easy as it looks here.

Calibrating, pointing, and drizzling Hubble Servicing Mission 3B in March 2002: ACS installed

Advanced Camera for Surveys (ACS)

New satellite discovery observations
· Hubble proposal designed by W eaver, Stern, et al., initially rejected, then accepted when STIS died · Advanced Camera for Surveys (ACS) W ide Field Channel (W FC) covers entire orbital stability zone · Pluto-Charon near chip gap: peek-a-boo! · 4 long exposures on May 15 and May 18, 2005, using only 2 orbits · Discovery on June 15: try it yourself...

Notice the star trails, cosmic rays, chip gap...

15 May 2005, frame 1

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Notice the star trails, cosmic rays, chip gap...

Dithering across the chip gap now...see anything?

15 May 2005, frame 2

15 May 2005, frame 3

Dithering across the chip gap now...see anything?

Looking for real objects among all the artifacts...

15 May 2005, frame 4

15 May 2005, sum 4 frames

Looking for real objects among all the artifacts...

Do it again 3 days later...where are the moons?

15 May 2005, median 4 frames

18 May 2005, frame 1

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Do it again 3 days later...where are the moons?

Dither across the gap...where are the moons?

18 May 2005, frame 2

18 May 2005, frame 3

Do it again 3 days later...where are the moons?

"Clean" image

18 May 2005, frame 4

18 May 2005, median 4 frames

"Clean" image

New moons are roughly 3-4x farther out than Charon, with possible 6:4:1 orbital resonances

S/2005 P 1

Charon

S/2005 P 2

15 May 2005, median 4 frames

15 and 18 May 2005, median 8 frames

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Pre-discovery observations in 2002
· Hubble program by Buie & Young · ACS High Resolution Channel · Primarily designed to map surface features (albedo) of Pluto and Charon · New moons marginally detected · Further observations will definitively determine orbits, and hopefully confirm these detections: are the satellites where they should be?

Initial thoughts
· Why is Pluto suddenly going so easy on us ?!? · Well-designed program: long exposure times (but not too long), two epochs...the gap is OK · Two objects! They somewhat validate each other, and assumptions about their similar orbits · Surprised they are so close to Pluto and Charon: expecting any moons to be farther out, but they don't violate dynamical constraints (Stern, 1994) · Could they be something other than moons?

The "checklist" of possible explanations
· · · · · Detector artifacts? Optical "ghosts" or scattered light? Overlapping cosmic rays or star trails? Real, but asteroids? KBO (Plutinos)? New moons of Pluto!

Confirmation and follow-up
· · · · Independent discovery in Aug 2005 by Andrew Steffl Search other existing data: Hubble, Subaru... Hubble follow-up: impossible until 15 Feb 2006 (2 gyros) Ground-based attempts to image the new moons in Sep/Oct: Keck, VLT, Gemini (difficult until spring 2006) · Checklist of alternate explanations: rule them out? · Confident enough to announce on 31 October 2005

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Preliminary assumptions and implications
· Orbits are co-planar with Charon, nearly circular, possibly in stable resonances with each other · No other moons of similar magnitude (unless artifacts hid them); very compact system · Pluto first KBO with multiple satellites: implies there are probably many more · Probably formed primordially with Charon (collision), not later (captured)

Relative sizes of Pluto, Charon, and new moons (P1 and P2)

P1 P2
2300 km 1200 km ~100 km

The new moons are roughly 12x smaller and 600x fainter than Charon, and 4000x fainter than Pluto

What does a "quadruple planet" look like?
http://www.stsci.edu/~mutchler/pluto_50.html

Announcement and publications

Animation produced with

9 Feb 2006

Celestia

W W St St

eaver eaver ern et effl et

et al, 2005, IAU Circular 8625 et al., 2006, Nature (accepted) al., 2006, Nature (accepted) al., Astronomical Journal (submitted)

Pre-prints available online at:

http://arxiv.org/archive/astro-ph

"Xena & Gabrielle"
Xena

The 10th planet?

Pluto

Moon

Earth

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Should we call Pluto a planet?
· I'm neutral. But some things to consider... · Is Pluto just the first of many Kuiper Belt "ice dwarf" planets discovered? · Is larger Xena the 10th planet? · Are slightly smaller Sedna, Quaoar planets? · Ceres was called a planet for ~50 years, then re-classified as an asteroid (a precedent) · Will we have only 8 planets, or hundreds of them? · Is this a problem? Seems like progress to me. · The IAU is working on it...in the meanwhile, it is a harmless and healthy "non-controversy"

Launch week, a.k.a...
Dad & Max Bill Nye

David Levy

New Horizons launch on 19 January 2006!

Hal W eaver signing the Atlas V rocket

"Nerdstock"

Launch parties
Annette and Patsy Tombaugh Jim Christy
In memory of Clyde W . Tombaugh, the American astronomer who discovered Pluto in 1930, NASA's New Horizons spacecraft carries a small aluminum canister containing some of Tombaugh's cremated remains, donated by his family. These remains will fly past Pluto with New Horizons on July 14, 2015, and then on past Kuiper Belt objects in the succeeding years. The memorial canister, about two inches wide and half-an-inch tall, is attached to the inside, upper deck of the spacecraft. Its inscription reads:

Interned herein are remains of American Clyde W. Tombaugh, discoverer of Pluto and the solar system's "third zone." Adelle and Muron's boy, Patricia's husband, Annette and Alden's father, astronomer, teacher, punster, and friend: Clyde W. Tombaugh (1906-1997)

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Kuiper Belt
2016-2020

Pluto
14 July 2015

Jupiter
28 Feb 2007

Launch
19 Jan 2006

Pluto-Charon Encounter Geometry Arrival July 14, 2015
Charon-Earth Occultation 14:17:50

P1

P2
Pluto-Earth Occultation 12:49:50 Charon

13:40

12:40

Pluto
0.24°

Charon-Sun Occultation 14:15:41 Pluto-Sun Occultation 12:49:00 · · · · · S/C trajectory time ticks: 10 min Charon orbit time ticks: 12 hr Occultation: center time Position and lighting at Pluto C/A Distance relative to body center

Sun Earth

11:40

Charon C/A 12:12:52 26,937 km 13.87 km/s

New Horizons mission

Pluto C/A 11:59:00 11,095 km 13.77 km/s

http://pluto.jhuapl.edu

http://www.rasastro.org

Questions?

RAS Junior Member, circa 1978

... AND TWO LITTLE MOONS ! http://pluto.jhuapl.edu http://www.stsci.edu/~mutchler

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