Lowell’s scientists help characterize Earth’s second known minima

Lowell’s scientists help characterize Earth’s second known minima

Press release from: Lowell Observatory
Published: Monday 23 November 2020

Astronomers using data collected with the Lowell Discovery Telescope (LDT) have helped characterize only the second least known Earth, a newly discovered asteroid with the designation 2020 CD3, or CD3 for short. The LDT observations helped clarify both the rotational speed and orbit of this tiny body, the latter of which helped prove that CD3 is a natural body and not a human-made space junk relic.

The minima are small asteroids temporarily captured in orbit around the Earth. Within about a year they are thrown back into interplanetary space. The first known minimum, 2006 RH120, was detected 14 years ago.

CD3 was discovered on February 15, 2020 by Kacper Wierzchos and Teddy Pruyne via the Catalina Sky Survey, which operates from the University of Arizona’s Lunar and Planetary Laboratory. Due to the rarity of the minima, a global effort led by postdoctoral researcher Grigori Fedorets of Queen’s University in Belfast was quickly launched to study this object. Twenty-three researchers from 14 academic institutions in seven countries participated, using different telescopes including the LDT. The team made observations until mid-May 2020 and published the results today in the Astronomical Journal.

Lowell Observatory astronomer Nick Moskovitz and former Lowell Arecibo Observatory postdoctoral researcher / current scientist Maxime Devogele participated in the effort, assisted in observing LDT by Quanzhi Ye of the University of Maryland. By measuring the CD3’s variable brightness over time (i.e., its light curve) with the Large Monolithic Imager (LMI) on the LDT, they determined that its rotational speed was about three minutes. Fedorets said: “Rotation speed was probably the biggest unanswered question in this research. Lowell’s team showed that it rotates slower than expected for objects of this size range.”

Moskovitz and his colleagues Lowell also used the LMI / LDT combination to precisely measure the position of CD3 to refine its orbit. This information combined with the physical characteristics of CD3, such as an inferred silicate composition, indicate that this is certainly a natural object. This sets it apart from another recently discovered object, 2020 SO, which scientists believe may be the upper stage of NASA’s Surveyor 2 spacecraft.

The study estimates that the CD3 is about 1-1.5 meters in diameter, about the size of a small car, and that it came within about 13,000 kilometers (8,100 miles) of Earth at its closest approach. Observing such small objects is challenging and requires a large enough telescope to see them. Furthermore, their transient nature means that the time window for observing them can close quickly. Enter the 4.3-meter LDT, the Lowell Observatory’s flagship telescope. Its large size and ready availability make it optimized for such studies. Moskovitz said: “This object was not bright enough to study it for a long time. The fact that we have this telescope in our backyard and we were able to respond quickly made a real difference.”

The global response to CD3 could very well serve as a model for future minimaon studies, which scientists predict will happen soon. According to Fedorets, “The minimums are expected to be discovered in large numbers in the following decade, with the opening of the Vera C. Rubin Observatory scheduled for 2023”. This facility is now under construction in Chile and features an 8.4-meter telescope that will allow astronomers to detect many smaller bodies such as minimions.

Scientists are interested in learning more about these bodies for several reasons. Since the minima are close to Earth, they are potentially accessible targets for robotic or human exploration. Such efforts will be scientifically valuable in understanding the origin of these objects and their relationship with other populations of asteroids and comets in the solar system. These objects could also one day be commercially important as targets for the extraction of resources in space.

Lowell Observatory owns and operates the LDT in partnership with Boston University, the University of Maryland, the University of Toledo, Northern Arizona University, and Yale University. Its primary imager is the LMI, featuring the largest charge-coupled device (CCD) produced. The camera provides a 0.2 degree by 0.2 degree field of view and was funded by the National Science Foundation.

Reference:
“Establishing Earth’s Minimoon Population through Characterization of Asteroid 2020 CD3”, Grigori Fedorets et al., November 23, 2020, Astronomical Journal [https://aj.aas.org, preprint: https://arxiv.org/abs/2011.10380].

Lowell Observatory Information:
Lowell Observatory is a private, non-profit 501 (c) (3) research institute founded in 1894 by Percival Lowell atop Mars Hill in Flagstaff, Arizona. The observatory has been the site of many important discoveries, including the first detection of large redshift rates of galaxies by Vesto Slipher in 1912-1914 and the discovery of Pluto by Clyde Tombaugh in 1930. Today , the observatory’s 14 tenured astronomers use NASA’s world-based telescopes, space telescopes and planetary spacecraft to conduct research in different areas of astronomy and planetary science. The Lowell Observatory currently operates multiple research tools at its Anderson Mesa station, east of Flagstaff, and the 4.3-meter Lowell Discovery Telescope near Happy Jack, Arizona. The observatory also welcomes more than 100,000 guests annually to its Mars Hill campus in Flagstaff, Arizona, for a variety of educational experiences, including historical tours, scientific presentations, and telescope viewing.

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