News Release Archive:

News Release 92 of 192

April 17, 2002 02:00 PM (EDT)

News Release Number: STScI-2002-04

Hubble Hunts Down Binary Objects at the Fringe of Our Solar System

Technical facts about this news release:

About the Object
Object Name: 1998 WW31
Object Description: Binary Kuiper Belt Object
Distance (from the Sun): The binary object has a semi-major axis of ~ 45 astronomical units (6.7 x 109 km or 4.2 x 109 miles).
Disance (from the Earth): During the time of the HST observations (July 2001- February 2002) the binary system was ~ 46.5 astronomical units from the Earth.
Distance (between the objects): The semi-major axis of the components of the binary system is ~ 22,300 km (13,900 miles). The eccentricity of the orbit makes this physical distance vary between 4,000 and 40,000 km (2,500 and 25,000 miles).
Orbital Period: The binary objects have an orbital period about each other of ~ 570 days.
Solar Orbital Period: The binary system orbits the Sun every 300 years.
Diameters: The binary objects are estimated to be roughly 150 km and 130 km in diameter.
Total Mass: The binary objects have a total mass of 0.00021 that of Pluto.
Dimensions: The HST image is roughly 7 arcseconds (roughly 226,000 km or 141,000 miles) across.
About the Data
Instrument: WFPC2
Exposure Date(s): 2001: July 12, August 9, September 10, December 30
Exposure Time: 2.5 hours
Filters: F555W (V), F675W (R), F814W (I)
Principal Astronomers: C. Veillet (CFHT), J. W. Parker (SwRI), I. P. Griffin (STScI), B. G. Marsden (SAO), A. Doressoundiram, (Observatoire de Paris), D. J. Tholen (Univ. of Hawaii), M.W. Buie (Lowell Obs.), M. J. Holman (SAO)
Summary of All Data
KPNO 4-m telescope: November 1998; January and November 1999; November 2000
CFH 3.6-m telescope:

January and December 2000; July - September 2001

July 2001- February 2002

About the Image
Image Credit: NASA and C. Veillet (CFHT)
Release Date: April 17, 2002