Discovery Of A Satellite Around The Transneptunian Object 1998 WW31

SPACE SCIENCE

1998 WW31 is the second transneptunian object (after Pluton) to have a satellite. The combined diameter of the pair is estimated at 150 km. The angular separation of 1.2" observed in December corresponds to an effective distance between the two components of approximately 40000 km (Pluto and Charon are distant by 19636 km). The difference in magnitude between 1998 WW31 and its satellite is estimated at 0.4, which thus gives a mass ratio of approximately 1.7 (ratio of ~8 for Pluto-Charon) the system 1998 WW31 is more a double planet than a planet-satellite system.

Paris - May 8, 2001
Alain Doressoundiram from the Observatoire de Paris and Christian Veillet from the CFH Institute have confirmed the discovery of the second transneptunian (Kuiper Belt) object 1998 WW31 is a double object.

It is during their multi-color photometry and recovery of transneptunian objects program that they made this discovery. This program is carried out on the Canada-France-Hawaii Telescope of 3.6 m located at 4200m on Mauna Kea, Hawaii. In December 2000, they pointed the telescope at 1998 WW31, a transneptunian object which required additional observation, without which they would have lost its position.

Its double nature or its elongated shape did not appear to them immediately at the time of the observations, but only later during the meticulous analysis of the data.

The transneptunian objects are small bodies of the Solar system located beyond the orbit of Neptune, at more than 30 astronomical units from the Sun (1 astronomical unit = distance Sun-Earth). They are icy bodies, very primitive as fossil remnants of the formation of the Solar system, 4.6 billion years ago.

The study of these objects, discovered for the first time less than ten years ago, is currently in full development. It can provide invaluable indices on the composition of the primitive nebula and on the processes prevailing at the beginning of the Solar system.

Moreover, the knowledge of the physical properties of the transneptunian objects could be a significant step in the study of circumstellar discs and planet formation around other stars that the Sun.

1998 WW31 like all the objects of the Solar system moves relative to fixed stars of the field. It is a weak object of 23.6 in magnitude and distant by 45.6 astronomical units from the Earth. 1998 WW31 appears undoubtedly double. The exceptional quality of the Mauna Kea site allowed the resolution of the pair (1.2 seconds of arc).

With only the images, two alternative interpretations were possible:

They are two transneptunian objects on distinct orbits but having by pure coincidence a common apparent motion over two nights!
1998 WW31 is undoubtedly a twin (like Pluto-Charon)

It is the second alternative, much more probable than the first, which proved to be right. Indeed, the CFHT archive images of January 7 2000, made it possible to find 1998 WW31. But the orientation of the pair, as well as the separation between the two components had changed: 1998 WW31 is actually a twin!

Veillet C, Doressoundiram A., Shapiro J, 2001, IAU Circular num. 7610

SPACE SCIENCE

Hubble Finds New Asteroid Moon

Los Angeles - March 21, 2001
Asteroid (107) Camilla has joined the ranks of asteroids boasting a small moon. Astronomers from Towson University in Maryland found the satellite in five images taken by the Hubble Space Telescope earlier this month.

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.