With the Hyper Suprime-Cam (HSC), an ultra-wide-field primary focus camera mounted on the Subaru Telescope, a new location is available at a very distant location of about 132 times the distance between the Sun and the Earth (132 astronomical units). A celestial body (nickname: Farfarout) was discovered. It is the celestial body with the longest distance at the time of discovery among the currently known celestial bodies in the solar system.
Farfarout was discovered by researchers at the Carnegie Institute in the United States, the University of Hawaii, and the University of Northern Arizona in 2018 with the Subaru Telescope, and after several years of follow-up observations with the Gemini Northern Telescope and Magellan Telescope, its orbit has been improved. I was asked. Currently, Farfarout is about 132 astronomical units from the Sun, about four times the distance between the Sun and Pluto. The farthest celestial body found in the solar system, 2018 VG 18 (nickname: Farout), was about 120 astronomical units at the time of its discovery. This is also an astronomical object discovered by the research team using the Subaru Telescope ( article released on December 17, 2018 ).
Dr. David Tholen (University of Hawaii) of the research team said, “It will take about 1000 years for Far Farout to orbit the Sun. It requires years of observation. “
Farfarout’s orbit is elongated, with the aphelion (farthest from the Sun) about 175 AUs and the perihelion (closest to the Sun) about 27 AUs inside Neptune’s orbit. The researchers speculate that the gravitational interaction with Neptune in the past may have caused the Farfarout’s orbit to become elongated. Dr. Chad Trujillo (Northern Arizona University) said, “Far Farout may have been pushed out of the solar system because it was too close to Neptune. Far Farout’s orbit is also interesting for understanding Neptune’s formation and evolution. Because the orbits intersect, there will continue to be opportunities for Far Farout and Neptune to have great gravitational interactions. “
Due to the strong influence of Neptune’s gravity, it is not possible to investigate the existence of unknown planets in the solar system from Farfarout’s orbit. The existence of the unknown planet “Planet Nine (Ninth Planet)”, which may be farther than Neptune, comes from the orbits of celestial bodies further outside Neptune’s orbit, such as “2012 VP 113 ” and “Sedna”. It has been suggested. The research team is exploring such trans-Neptunian objects using the Subaru Telescope (Reference: Article released on October 3, 2018 ).
The research team estimates the diameter of Farfarout to be about 400 kilometers, based on the brightness and distance of Farfarout and the assumption that it is an ice-rich object. If it is a dwarf planet, it is a celestial body near the lower limit.
Dr. Scott Sheppard (Carnegie Institution for Science) said, “The discovery of Farfarout shows that humans’ ability to capture the whole picture of the outer edge of the solar system and explore further distances has improved. The recent development of attached giant digital cameras has made it possible for the first time to efficiently find distant objects such as Farfarout, even if they are quasi-planetary in size. It is observed as a very dark celestial body because it is far away. Far-far-out is probably just the tip of an ice mine among the celestial bodies at the end of the solar system. ” He talks about his expectations.
This new object was given the provisional designation “2018 AG 37 ” on February 10, 2021 by the International Astronomical Union Minor Planet Center ( Minor Planet Electric Circular 2021-C187 ). The official name will be given after more accurate orbits have been determined in observations over the next few years.
Featured image: Discovered images of Far Far Out (2018 AG 37 ) observed by the Subaru Telescope on January 15 and 16, 2018 . You can see the movement of the new celestial body from the images taken after a while. (Credit: Scott S. Sheppard)