The asteroid called “baby of Lucy” It is between 2 and 3 million years old, reveals a new method
▲ A pair of stereoscopic images of Dinkinesh and Selam created with data collected by the L’Lorri camera Lucy.Foto NASA/ Goddard/ Johns Hopkins Apl
Europa Press
La Jornada Newspaper
Tuesday, May 7, 2024, p. 6
Madrid. An asteroid nicknamed “the baby of Lucy”, that orbits another and which was discovered in November by a NASA spacecraft, is only between 2 and 3 million years old.
Using novel statistical calculations, a Cornell University team estimated the age of Selam, a moon surrounding tiny Dinkinesh in the main asteroid belt between Mars and Jupiter, based only on dynamics, or how the pair moves in the space. Your calculation agrees with one of the mission Lucy from NASA, based on an analysis of surface craters, the most traditional method for dating asteroids.
The new method complements that work and has some advantages: it does not require an expensive spacecraft to capture close-up images, it could be more accurate in cases where asteroid surfaces have undergone recent changes, and it can be applied to secondary bodies in dozens of other known binary systems, representing 15 percent of near-Earth asteroids, researchers said.
Finding the ages of asteroids is important to understanding them, and this one is remarkably young compared to the age of the solar system, meaning it formed recently, Colby Merrill, a doctoral student in the field of aerospace engineering, said in a statement. and lead author of the new study, published in Astronomy & Astrophysics. Getting the age of this body can help us understand the population as a whole, he added.
Complex and fascinating objects
Binary asteroids are dynamically complex and fascinating objects that engage in a kind of tug-of-war, the researchers noted. Gravity acting on objects causes them to physically bulge and produces tides, which slowly reduce the energy of the system. Meanwhile, radiation from the Sun also alters the energy of the binary system with the so-called Yarkovsky-O’Keefe-Radzievskii-Paddack (Byorp) effect.
Over time, the system will reach an equilibrium in which the tides and the Byorp are equally strong: a stalemate in the tug-of-war.
Assuming those forces were in balance and plugging the mission’s publicly shared asteroid data Lucy, The researchers calculated how long it would have taken for Selam to reach its current state after forming from surface material ejected by a rapidly spinning Dinkinesh. Along the way, the team noted that it improved pre-existing equations that assumed both bodies were equally dense and ignored the mass of the secondary body.
By performing around a million calculations with different parameters, the results produced an average age for Selam of 3 million years, with 2 million being the most likely result.
Binary systems
Determination of Selam’s age advances comparisons with Didymos and Dimorphos, the even younger system targeted by the mission DART from NASA, and contributes to the understanding that binary systems are created continuously. The researchers now hope to apply their new aging method to other binary systems in which the dynamics have been well characterized, even without close flybys.
Used in conjunction with crater counting, this method could help better constrain the age of a system. If we use two methods and they match each other, we can be more confident that we are getting a meaningful age that describes the current state of that system, Kubas said.
Calculations suggest that the asteroid Selam is younger than the fossil of the human ancestor on Earth for which it is named: the skeletal remains of a 3-year-old girl found in Ethiopia, which was determined to be 3.3 million years old.
Selam means peace in the Ethiopian language and has also been nicknamed “the baby of Lucy”, in reference to the famous remains of a human ancestor found in 1974 and nicknamed Lucy or Dinkinesh.
NASA’s mission is on track to study Trojan asteroids in Jupiter’s orbit in 2027.
