Testing of citizen scientist discovery suggests it is on the boundary between comet and asteroid
source : phys.org
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Images from DQ 2009118 (green dotted lines) with the tail of a comet (white arrows). Frames (a) and (b) are from the first activity era and are the result of our Active Asteroids citizen scientist project and archival research. Frame (c) is a follow-up image of APO showing faint signs of activity, resulting in the tentative discovery of the second epoch of activity. In frames (a) through (c), the negative heliocentric velocity (black arrow outlined in red) and antisolar (yellow arrow) directions projected onto the plane of the sky coincide with each other and the direction of the tail. Frame (d) is a stack of our Magellan follow-up observations confirming the discovery of the second activity epoch. In this image, the tail is oriented between the directions of antisolar (yellow arrow) and negative heliocentric velocity (black arrow outlined in red), projected onto the plane of the sky. North is top and east is left in each image (solid green arrows), and all directions refer to the ephemeris location of 2009 DQ118 (which is centered in each image) at the time of observation, as given by JPL Horizons (Giorgini et al. 1996). (a) 300 s VR-band Dark Energy Camera (DECam) image taken with the 4 m Blanco Telescope at Cerro Tololo Inter-American Observatory (CTIO), Chile, at UT 2016 on March 8 (Prop. ID 2016A-0189; PI : Rust; observers: A. Rust, DJJ). (b) 200 s r-band DECam image, UT 2016 March 9 (Prop. ID 2015A-0121; PI: von der Linden; observer: A. von der Linden). (c) 300 s VR tape recording taken with the Astrophysical Research Consortium Telescope Imaging Camera (ARCTIC) on the APO 3.5 m Astrophysical Research Consortium (ARC) Telescope, UT 2023, February 24 (Prop. ID 2Q2023-UW08; PI: Chandler; observer: C. Chandler). (d) A merged stack of four 150 s WB4800-7800 band images taken with the Inamori-Magellan Areal Camera and Spectrograph (IMACS) on the 6.5 m Magellan Baade Telescope at Las Campanas Observatory, Chile, on UT 2023 April 22 (PI: S. Sheppard; observer: S. Sheppard). Credit: The astrophysical diary letters (2023). DOI: 10.3847/2041-8213/acfcbc
A team of space scientists, astronomers and astrophysicists from multiple US institutions, working with a colleague from Italy, has determined that a celestial body spotted by citizen scientists in 2016 is neither a comet nor an asteroid, but an object that lies . on the border between the two. In their article published in the magazine The astrophysical diary letters, the group describes the multiple tests they did to determine the nature of the object and what they learned as a result.
While much space science is conducted by professionals in the field, much is also done by so-called citizen scientists: people with an interest in space who participate by using amateur telescopes to look at the night sky.
In this new effort, a group of such citizen scientists discovered an object in the night sky that had not yet been identified by the scientific community. They continued their work by searching publicly available archival data and found images of the object, but no cases where it had been singled out. In doing so, they found what they described as clear signs of comet behavior. The group registered the object with the Active Asteroid project, where it came to the attention of the research team.
The research team promptly named the object quasi-Hilda 2009 DQ118. The Hildas are a group of comets and asteroids located between the Trojans and the main asteroid belt. However, the object found by the citizen scientists was not a real Hilda asteroid, hence the quasi-title.
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Orbits of representative bodies (blue curves) from eight dynamical classes in the corotating frame with Jupiter (orange line) illustrating the similarities between 2009 DQ118 and other quasi-Hildas. Each subplot shows 200 years of orbital integration in this frame of reference. (a) Active asteroid 2015 VA108 orbits in the main asteroid belt and is a main belt comet candidate (Chandler et al. 2023). (b) Near-Earth binary asteroid (65803) Didymos-Dimorphos was the target of the NASA Double-Asteroid Redirection Test (DART) mission. It is the first artificial active asteroid (Li et al. 2023). (c) Active Centaur (2060) Chiron (95P) is between the orbits of Jupiter and Uranus. (d) JFC 67P/Churyumov-Gerasimenko crosses the orbits of Jupiter and Mars. It was visited by the ESA Rosetta spacecraft. (e) Long-period comet C/2014 UN271 (Bernardinelli-Bernstein) is currently entering from the Oort Cloud and will reach perihelion in January 2031, near Saturn’s orbit. Because this comet has a large obliquity (i ≈ 95°), it appears to be within Jupiter’s orbit in part of this XY projection. (f) Trojan asteroid (3548) Eurybates in a characteristic Trojan tadpole orbit, indicative of a 1:1 mean motion resonance with Jupiter. Eurybates is a target of the NASA Lucy spacecraft mission. (g) Asteroid (153) Hilda in its iconic 3:2 internal mean motion resonance with Jupiter. Hilda asteroids are in this resonance and also show this three-lobed pattern in this frame. (h) Active quasi-Hilda 282P/(323137) 2003 BM80 exhibits a typical asymmetric quasi-Hilda corotating pattern (Chandler et al. 2022). (i) 2009 DQ118 with a quasi-Hilda track similar to 282P. Credit: The astrophysical diary letters (2023). DOI: 10.3847/2041-8213/acfcbc
After studying twenty images of the object found in the archives, the researchers examined it using both the Astrophysical Research Consortium Telescope and the Magellan Baade Telescope. In doing so, they found what they described as a second epoch of activity related to the object. They then performed photometric analysis of the tail and found that it was approximately the same length and brightness in all images taken. They also tracked orbital history using dynamic simulations.
The team’s work showed that the object was indeed a quasi-Hilda and that it regularly passed near Jupiter as it orbited the Sun. The researchers found no evidence that the object is a comet or an asteroid. It was neither mainly ice nor mainly rock, which placed it on the border between the two.
More information:
William J. Oldroyd et al, Recurring Activity Discovered on Quasi-Hilda 2009 DQ118, The astrophysical diary letters (2023). DOI: 10.3847/2041-8213/acfcbc
Magazine information:
Astrophysical diary letters
© 2023 Science X Network
source : phys.org
