47171 Lempo

47171 Lempo

47171 Lempo, also known as (47171) Lempo–Hiisi, is a special object in space found beyond the planet Neptune. It is called a trans-Neptunian object and is located in a distant area of our Solar System called the Kuiper belt.

This object was discovered on October 1, 1999, by American astronomers Eric Rubenstein and Louis-Gregory Strolger while they were using telescopes at the Kitt Peak National Observatory in Arizona, United States.

Lempo moves in a special pattern related to the planet Neptune, which helps scientists classify it as a plutino.

The object got its name from Lempo, a figure in Finnish mythology. Later, scientists found two smaller objects moving together with Lempo. These were named Paha and Hiisi.

History

Discovery

The Lempo system was found on October 1, 1999, by American astronomers Eric Rubenstein and Louis-Gregory Strolger. They were working at the Kitt Peak National Observatory in Arizona. They were studying stars when they saw a bright object moving slowly in the sky. This object was later named Lempo.

After finding Lempo, Rubenstein and Strolger watched it for three more days to make sure it was real. They found it in pictures taken before they first saw it. They told scientists around the world about the discovery in December 1999. Lempo was given a special number, 1999 TC₃₆, to show when it was found. By 2002, they had watched Lempo long enough to learn its path around the Sun, and it was given the permanent number 47171. By 2021, over 500 observations of Lempo had been recorded.

Name

Lempo is named after a character from Finnish mythology. In old stories, Lempo was first seen as a god but later as a tricky spirit. The two smaller parts of the Lempo system are named after Lempo's friends, Hiisi and Paha. These names were chosen by astronomer Bryan J. Holler, and the official name was announced in 2017. Hiisi is also the name of a faraway planet called HAT-P-38b.

Triple system

Lempo is a special group of three objects moving around each other in space. It has a central pair called Lempo and Hiisi, which spin around each other. A smaller object named Paha moves around this central pair.

Lempo and Hiisi are almost the same size, while Paha is much smaller. Scientists found Paha in 2001 using a powerful telescope. This system is one of only a few known objects in space that has three parts moving together.

System dynamics

The way the Lempo system moves in space is very complicated. We don't fully understand how the pieces spin or their shapes, which makes it hard to explain their movement together. A study in 2018 showed that even with good guesses about these details, the orbits of the pieces did not match what we see. Researchers think we need better measurements to make a more detailed model.

Origin

There are two main ideas about how this triple space object formed. One idea is that a big crash happened, and then the pieces came back together. Another idea is that a third object was pulled in by the gravity of two objects that were already together.

Physical characteristics

Observations from space telescopes like the Spitzer Space Telescope, Herschel Space Telescope, and the Hubble Space Telescope help scientists learn about objects like Lempo. Lempo is about 393 kilometers across.

Studies show that Lempo has a very low density, meaning it is likely made of pieces of rock and ice. Its surface looks red and has some signs of water ice. These details come from studying the light reflected from Lempo.

Exploration

The Lempo system is interesting for future space missions. Scientists have thought about sending a spacecraft called New Horizons 2 to visit Lempo and other objects.