Optical Spectropolarimetry of Binary Asteroid Didymos–Dimorphos before and after the DART Impact

Bagnulo, S.; Gray, Zuri; Granvik, Mikael; Cellino, A.; Kolokolova, Ludmilla; Muinonen, K.; Muñoz, Olga; Opitom, Cyrielle; Penttilä, Antti; Snodgrass, C.

doi:10.3847/2041-8213/acb261

Cited by 11 publications

(16 citation statements)

References 44 publications

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“…This study presents new ground-based telescopic data from September 26 through November 1. The data presented expand upon previously reported ejecta results (Bagnulo et al 2023;Graykowski et al 2023;Li et al 2023;Opitom et al 2023) which have shown the evolution of the ejecta to be a significantly more complex and long-lasting process than anticipated prior to impact. This work combines data from 12 Earth-based facilities that were collected with denser temporal sampling and with wider fields of view than the other published studies.…”

Section: Introductionsupporting

confidence: 85%

Ejecta Evolution Following a Planned Impact into an Asteroid: The First Five Weeks

Kareta,

Thomas,

et al. 2023

ApJL

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The impact of the Double Asteroid Redirection Test spacecraft into Dimorphos, moon of the asteroid Didymos, changed Dimorphos’s orbit substantially, largely from the ejection of material. We present results from 12 Earth-based facilities involved in a world-wide campaign to monitor the brightness and morphology of the ejecta in the first 35 days after impact. After an initial brightening of ∼1.4 mag, we find consistent dimming rates of 0.11–0.12 mag day−1 in the first week, and 0.08–0.09 mag day−1 over the entire study period. The system returned to its pre-impact brightness 24.3–25.3 days after impact though the primary ejecta tail remained. The dimming paused briefly eight days after impact, near in time to the appearance of the second tail. This was likely due to a secondary release of material after re-impact of a boulder released in the initial impact, though movement of the primary ejecta through the aperture likely played a role.

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Section: Introductionsupporting

confidence: 85%

Ejecta Evolution Following a Planned Impact into an Asteroid: The First Five Weeks

Kareta,

Thomas,

et al. 2023

ApJL

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“…The DART spacecraft impacted Dimorphos at 23:14 UT on 2022 September 26. Our observations span a period from about 1 month before to almost 4 months after the impact, with a number of the VLT observations being made hand in hand with spectropolarimetric observations (Bagnulo et al 2023)-this has been indicated in the observing log. Considering the entire observing campaign, we have observed the asteroid system in three stages.…”

Section: Observationsmentioning

confidence: 92%

“…Therefore, we first converted our R-and B-band measurements to the V band before using the above expression to calculate the geometric albedo. According to the spectropolarimetric measurements of Bagnulo et al (2023), the ratio between measurements in the V and R bands are nearly constant with phase angle, i.e., (P Q (V ) − P Q (R))/P Q (R) ∼ 0.05, as well as between the V and B bands,…”

Section: Polarimetric Phase Curvementioning

confidence: 99%

Polarimetry of Didymos–Dimorphos: Unexpected Long-term Effects of the DART Impact

Gray,

Bagnulo,

Granvik

et al. 2024

Planet. Sci. J.

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We have monitored the Didymos–Dimorphos binary system in imaging polarimetric mode before and after the impact from the Double Asteroid Redirection Test mission. A previous spectropolarimetric study showed that the impact caused a dramatic drop in polarization. Our longer-term monitoring shows that the polarization of the post-impact system remains lower than the pre-impact system even months after the impact, suggesting that some fresh ejecta material remains in the system at the time of our observations, either in orbit or settled on the surface. The slope of the post-impact polarimetric curve is shallower than that of the pre-impact system, implying an increase in albedo of the system. This suggests that the ejected material is composed of smaller and possibly brighter particles than those present on the pre-impact surface of the asteroid. Our polarimetric maps show that the dust cloud ejected immediately after the impact polarizes light in a spatially uniform manner (and at a lower level than pre-impact). Later maps exhibit a gradient in polarization between the photocentre (which probes the asteroid surface) and the surrounding cloud and tail. The polarization occasionally shows some small-scale variations, the source of which is not yet clear. The polarimetric phase curve of Didymos–Dimorphos resembles that of the S-type asteroid class.

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“…Apart from the plume, a fraction of the ejected mass was emitted at significantly lower speeds, forming the ejecta pattern and tail that could be seen on the earliest images acquired from ground-based observatories (Bagnulo et al 2023;Opitom et al 2023) and the HST . Our purpose is to characterize the dust properties of this mostly slow-moving ejecta, the ejection velocities, the size distribution, and the ejected mass using Monte Carlo models to simulate the motion of the particles in the spatial region near the binary system.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Ejecta from the NASA/DART Impact on Dimorphos: Observations and Monte Carlo Models

Moreno,

Bagatin,

Tancredi

et al. 2023

Planet. Sci. J.

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The NASA Double Asteroid Redirection Test (DART) spacecraft successfully crashed on Dimorphos, the secondary component of the binary (65803) Didymos system. Following the impact, a large dust cloud was released, and a long-lasting dust tail developed. We have extensively monitored the dust tail from the ground and the Hubble Space Telescope. We provide a characterization of the ejecta dust properties, i.e., particle size distribution and ejection speeds, ejection geometric parameters, and mass, by combining both observational data sets and using Monte Carlo models of the observed dust tail. The size distribution function that best fits the imaging data is a broken power law having a power index of –2.5 for particles of r ≤ 3 mm and –3.7 for larger particles. The particles range in size from 1 μm up to 5 cm. The ejecta is characterized by two components, depending on velocity and ejection direction. The northern component of the double tail, observed since 2022 October 8, might be associated with a secondary ejection event from impacting debris on Didymos, although is also possible that this feature results from the binary system dynamics alone. The lower limit to the total dust mass ejected is estimated at ∼6 × 106 kg, half of this mass being ejected to interplanetary space.

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Optical Spectropolarimetry of Binary Asteroid Didymos–Dimorphos before and after the DART Impact

Cited by 11 publications

References 44 publications

Ejecta Evolution Following a Planned Impact into an Asteroid: The First Five Weeks

Ejecta Evolution Following a Planned Impact into an Asteroid: The First Five Weeks

Polarimetry of Didymos–Dimorphos: Unexpected Long-term Effects of the DART Impact

Characterization of the Ejecta from the NASA/DART Impact on Dimorphos: Observations and Monte Carlo Models

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