Subaru, Keck I and II, and the IRTF at sunset, as seen from Gemini North | © Alex Parker | Astronomy Department, University of Victoria

Ultra-Wide Trans-Neptunian Binaries: Mutual Orbit Movie

Click on the picture above to see the animation (13.7 MB H264 format).

Shown here are the six of the widest-known Trans-Neptuninan binaries and their measured mutual orbits. The binaries are rendered in 0.35-arcsecond seeing, and astrometric measurements of the secondary's location with respect to the primary are overlain at the time of observation. Red points indicate key data taken from the Gemini North observatory, primarily as part of observing programs associated with my PhD thesis research. Blue points indicate data taken at other facilities (including VLT, WIYN, Palomar, CFHT, Magellan, Keck, and HST).

This movie shows the binaries as they are observed from Earth over the period from 2000-2013. The resulting on-sky behavior is somewhat complex, due to the varying viewing geometry from Earth's and the binary system's orbital motions. In this time, all illustrated binaries except 2001 QW322 will have completed at least one mutual orbit (2001 QW322 has a mutual orbit period of approximately 17.4 years)

This sample contains the widest known binary minor planet - 2001 QW322, which has a separation in excess of 100,000 km and occupies nearly a quarter of its Hill sphere. It also contains the most eccentric binary minor planet known - L5c02, with a mutual eccentricity of 0.9. During pericenter passages, the secondary appears three times the size of the full Moon in the sky of the primary, while at apocenter it appears only a fifth the size of the full Moon. One final superlative object is 2000 CF105, with the lowest measured mass of any Trans-Neptunian Object - the system as a whole masses 1.8E17 kg, or roughly the same mass as Mauna Loa, the largest volcano on Earth.

Animation details: Rendered with a 10-day timestep in simulated 0.35 arcsecond seeing (roughly the best seeing achieved during our observational campaign). Lower right bars are 1 arcsecond on a side and point North and East. Nominal best-fit orbit illustrated. One-sigma astrometric uncertainty reflected in size of data points, while the color of the data points indicates data taken from Gemini North (red) or other facilities (blue). The tones played indicate observations; the pitch of each note is unique to each binary, while the volume is proportional to the precision of the measurement (louder = better observation).

The CFEPS objects now have MPC designations: b7Qa4 is 2006 BR284, hEaV is 2006 JZ81, and L5c02 is 2006 CH69.