A contact binary satellite of the asteroid (152830) Dinkinesh

Asteroids with diameters less than about 5 km have complex histories because they are small enough for radiative torques (that is, YORP, short for the Yarkovsky–O’Keefe–Radzievskii–Paddack effect) 1 to be a notable factor in their evolution 2 . (152830) Dinkinesh is a small asteroid orbiting the Sun...

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Bibliographic Details
Published in:	Nature (London) Vol. 629; no. 8014; pp. 1015 - 1020
Main Authors:	Levison, Harold F., Marchi, Simone, Noll, Keith S., Spencer, John R., Statler, Thomas S., Bell, James F., Binzel, Richard, Bottke, William F., Brown, Michael E., Buie, Marc W., Christensen, Philip R., Dello Russo, Neil, Emery, Joshua P., Grundy, William M., Hahn, Matthias, Kaplan, Hannah, Lauer, Tod R., Manzoni, Claudia, Martin, Audrey C., May, Brian H., Mottola, Stefano, Pätzold, Martin, Porter, Simon, Preusker, Frank, Protopapa, Silvia, Reuter, Dennis C., Robbins, Stuart J., Salmon, Julien, Simon, Amy A., Stern, S. Alan, Sunshine, Jessica M., Wong, Ian, Weaver, Harold A., Andrews, John, Anwar, Saadat, Barnouin, Olivier S., Beasley, Matthew, Berry, Kevin E., Birath, Emma, Bolin, Bryce, Booco, Mark, Burns, Rich, Campbell, Pam, Carpenter, Russell, Crombie, Katherine, Effertz, Mark, Eifert, Emily, Ellis, Caroline, Fischetti, Joel, Fleming, Paul, Francis, Kristen, Franco, Ray, Freund, Sandy, Gallagher, Claire, Gobat, Caden, Gorgas, Donovan, Granat, Chris, Gray, Sheila, Harch, Ann, Isabelle, Chris, Jackson, Bill, Kaufmann, David, Keeney, Brian A., Kennedy, Thomas, Lauffer, Karl, Lessac-Chenen, Erik, Leonard, Rob, Levine, Andrew, Lunsford, Allen, Martin, Tim, McAdams, Jim, Mehall, Greg, Merkley, Trevor, Miller, Graham, Montanaro, Matthew, Montgomery, Anna, Myers, Maxwell, Nelson, Derek S., Ocampo, Adriana, Olds, Ryan, Perkins, Trevor, Pineau, Jon, Poland, Devin, Ramanan, Vaishnavi, Rose, Debi, Sahr, Eric, Short, Owen, Solanki, Ishita, Stanbridge, Dale, Sutter, Brian, Talpas, Zachary, Taylor, Howard, Treiu, Bo, Vermeer, Nate, Vincent, Michael, Wallace, Mike, Weigle, Gerald, Wibben, Daniel R., Wiens, Zach, Wilson, John P.
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 30-05-2024 Nature Publishing Group
Subjects:	639/33/445/536 639/33/445/848 Angular momentum Asteroids Diameters Geomorphology Humanities and Social Sciences Light multidisciplinary Orbits Radiation Science Science (multidisciplinary)
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Summary:	Asteroids with diameters less than about 5 km have complex histories because they are small enough for radiative torques (that is, YORP, short for the Yarkovsky–O’Keefe–Radzievskii–Paddack effect) 1 to be a notable factor in their evolution 2 . (152830) Dinkinesh is a small asteroid orbiting the Sun near the inner edge of the main asteroid belt with a heliocentric semimajor axis of 2.19 au ; its S-type spectrum 3 , 4 is typical of bodies in this part of the main belt 5 . Here we report observations by the Lucy spacecraft 6 , 7 as it passed within 431 km of Dinkinesh. Lucy revealed Dinkinesh, which has an effective diameter of only 720 m, to be unexpectedly complex. Of particular note is the presence of a prominent longitudinal trough overlain by a substantial equatorial ridge and the discovery of the first confirmed contact binary satellite, now named (152830) Dinkinesh I Selam. Selam consists of two near-equal-sized lobes with diameters of 210 m and 230 m. It orbits Dinkinesh at a distance of 3.1 km with an orbital period of about 52.7 h and is tidally locked. The dynamical state, angular momentum and geomorphologic observations of the system lead us to infer that the ridge and trough of Dinkinesh are probably the result of mass failure resulting from spin-up by YORP followed by the partial reaccretion of the shed material. Selam probably accreted from material shed by this event. Observations from the Lucy spacecraft of the small main-belt asteroid (152830) Dinkinesh reveals unexpected complexity, with a longitudinal trough and equatorial ridge, as well as the discovery of the first contact binary satellite.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0028-0836 1476-4687 1476-4687
DOI:	10.1038/s41586-024-07378-0