Within days of the announcement by NASA’s Minor Planet Center of the discovery of the first-ever interstellar object, ‘Oumuamua, B612’s new Asteroid Institute began a collaborative effort that led to significant analysis about the discovery.
Bryce Bolin, a senior researcher at the Asteroid Institute as well as a DIRAC Institute Fellow, was the lead author on the study measuring 1I/’Oumuamua shape and rotation, and this research paper has been submitted for publication to The Astrophysical Journal.
B612 announced the Asteroid Institute in June 2017. It is a virtual research organization which has a particularly close working collaboration with the Data Intensive Research in Astrophysics and Cosmology Center (DIRAC) within the Department of Astronomy of the University of Washington. The B612 Asteroid Institute is led by three time US astronaut Dr. Ed Lu and dedicated to protecting Earth from Asteroid impacts.
First Discovery of an Interstellar Object
“Initially designated as a comet by the Minor Planet Center, C/2017 U1, the ISO now known as 1I/’Oumuamua wasn’t behaving like a comet, which raised questions about its origins,” stated Bolin in their findings.
“Initially, the object was thought to originate far outside the solar system in a region known as the Oort cloud where it can have extreme orbits that take them careening through the inner solar system at speeds exceeding 60 km/s. What made the apparition of 1I/’Oumuamua different and significant is that its speed was too high to have a solar system origin. As it was passing within perihelion distance, 1I was moving at 87.7 km/s, about 4.2 km/s too fast for it to be bound to the sun.
Bolin and collaborators at UW, Johns Hopkins Applied Physics Lab, University of Central Florida and Universite Cote d’Azur, Observatoire de la Cote d’Azur, viewed the ISO on the Apache Point 3.5 m telescope in Sunspot, NM to obtain images of I1 as it passed through the desert sky. The view provided the team the first time to study an object from another solar system, while it was still confined to our solar system – all at unprecedented levels of detail.
What they discovered was that ‘Oumuamua had significant characteristics in color, shape and rotation that made it different from other asteroids in our solar system.
“Photometric colors and spectra telling the chemical composition of the surface of 1I were taken, and study revealed that it has a reddish color and probably came from the inner part of its original system where its host star’s heat played an important role in the formation of asteroids and planets. Additionally, the object’s rotation was studied revealing that the object was shaped like a potato fingerling,” explained Bolin.
Understanding the rotation was challenging. “We used statistical methods originally developed in geophysics and open-source software first used for the detection of exoplanets. This was the first time these methods were ever used to measure the rotation of an asteroid and turned out be very powerful in extracting useful information from a very small set of data points”, added Dr. Daniela Huppenkothen, Associate Director for DIRAC and a co-author of the study.
In addition to publishing the results, the team made all of their raw data and analysis notebooks publicly available. “We are strong believers in making it possible for other researchers to verify, re-use, and build upon our work. Transparency, open data, and open science are one of the core tenets of both DIRAC and the Asteroid Institute.” said Professor Mario Juric, Bolin’s postdoctoral advisor at the University of Washington.
The last time a non-man made object was seen leaving our solar system was in 1980 with the discovery of comet C/1980 E1 Bowell. C/1980 was not a true interstellar object because it originated inside our solar system and was thrown out of the confines of our Sun’s gravity because of the strong gravitational influence of Jupiter. Given that the existence of an ISO is so novel, ‘Oumaumua was designated with the number “1” and its name meaning “first messenger” in Hawaiian.
Clues to the Elongated Shape of I1
“It’s thought that objects that are elongated, like I1 have plasticity and are shaped by being stretched, and elongated when they encounter the gravity of a planet during a close approach,” said Bolin. “It is still unknown if this implied that 1I experienced a gravitationally stretching event before it was ejected from its own solar system? Time can only tell as we gather more data.”