Breakup of a long-period comet as the origin of the dinosaur extinction

Siraj, Amir; Loeb, Abraham

doi:10.1038/s41598-021-82320-2

Cited by 24 publications

(48 citation statements)

References 57 publications

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“…Zahnle & Mac Low 1994) could give rise to fortuitous collisions that are, in fact, frequent in the mature stages of planetary systems. Also, despite impacts of comets against the Earth during the K/T mass extinction event (Siraj & Loeb 2021) are still debated due to a lack of well-established evidence in the Solar System (Desch et al 2021), this scenario might be somewhat frequent especially during the early stages of planetary evolution and might lead to the formation of rings around moons.…”

Section: Summary and Discussionmentioning

confidence: 99%

Cronomoons: origin, dynamics, and light-curve features of ringed exomoons

Sucerquia,

Alvarado-Montes,

Bayo

et al. 2021

Preprint

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In recent years, technical and theoretical work to detect moons and rings around exoplanets has been attempted. The small mass/size ratios between moons and planets means this is very challenging, having only one exoplanetary system where spotting an exomoon might be feasible (i.e. Kepler-1625b i). In this work, we study the dynamical evolution of ringed exomoons, dubbed cronomoons after their similarity with Cronus (Greek for Saturn), and after Chronos (the epitome of time), following the Transit Timing Variations (TTV) and Transit Duration Variation (TDV) that they produce on their host planet. Cronomoons have extended systems of rings that make them appear bigger than they actually are when transiting in front of their host star. We explore different possible scenarios that could lead to the formation of such circumsatellital rings, and through the study of the dynamical/thermodynamic stability and lifespan of their dust and ice ring particles, we found that an isolated cronomoon can survive for time-scales long enough to be detected and followed up. If these objects exist, cronomoons' rings will exhibit gaps similar to Saturn's Cassini Division and analogous to the asteroid belt's Kirkwood gaps, but instead raised due to resonances induced by the host planet. Finally, we analyse the case of Kepler-1625b i under the scope of this work, finding that the controversial giant moon could instead be an Earth-mass cronomoon. From a theoretical perspective, this scenario can contribute to a better interpretation of the underlying phenomenology in current and future observations.

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Section: Summary and Discussionmentioning

confidence: 99%

Cronomoons: origin, dynamics, and light-curve features of ringed exomoons

Sucerquia,

Alvarado-Montes,

Bayo

et al. 2021

Preprint

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“…The flux of cometary impactors is negligible compared to asteroids (e.g., dormant JFCs contribute by <1%; G18). Siraj and Loeb (2021) proposed that the impactor was a piece of a large long-period comet that tidally disrupted near its perihelion. This exotic idea has a number of problems, including the very low likelihood of terrestrial impacts from the long-period comets, the low efficiency of tidal disruption to make D 10 km fragments, and the general assumption that the geochemical signature of a cometary impactor would be consistent with the CM composition inferred for the K/Pg impactor.…”

Section: Implications For K/pg-scale Impactsmentioning

confidence: 99%

Dark Primitive Asteroids Account for a Large Share of K/Pg-Scale Impacts on the Earth

Nesvorný¹,

Bottke²,

Marchi³

2021

Preprint

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A dynamical model for large near-Earth asteroids (NEAs) is developed here to understand the occurrence rate and nature of Cretaceous-Paleogene (K/Pg) scale impacts on the Earth. We find that 16-32 (2-4) impacts of diameter D > 5 km (D > 10 km) NEAs are expected on the Earth in 1 Gyr, with about a half of impactors being dark primitive asteroids (most of which start with semimajor axis a > 2.5 au). These results explain why the Chicxulub crater, the third largest impact structure found on the Earth (diameter ≃ 180 km), was produced by impact of a carbonaceous chondrite. They suggest, when combined with previously published results for small (D 1 km) NEAs, a size-dependent sampling of the main belt. We conclude that the impactor that triggered the K/Pg mass extinction ≃ 66 Myr ago was a main belt asteroid that quite likely (≃ 60% probability) originated beyond 2.5 au.

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“…Siraj & Loeb [1] cite good evidence that the Chicxulub impactor was carbonaceous chondrite-like, but then assert that 100% of comets satisfy this constraint but only 10% of asteroids do. This assertion conflates carbonaceous chondrites with specific types (CB, CH, CI, CM, CO, CR, CV) of carbonaceous chondrites.…”

Section: Geochemical Argumentsmentioning

confidence: 99%

“…Siraj & Loeb [1], citing Bottke et al [7], claim only 30% of asteroids are C-type (spectrally resembling carbonaceous chondrites) and appear to imply that only 40% of carbonaceous chondrites are the specific type CM associated with the impactor. In fact the fraction of asteroids that are C-type is > 50% [8].…”

Section: Geochemical Argumentsmentioning

confidence: 99%

“…A carbonaceous chondrite-like asteroid of this size would likely deliver ≈ 2.3 × 10 11 g or Ir [5], in the center of the estimated mass range of the global Ir layer; but a comet would only deliver ∼ 0.1 × 10 11 g, because it is smaller and mostly ice. Against this backdrop, Siraj & Loeb [1] have argued in favor of a comet over an asteroid, based on dynamical and geochemical evidence. Here we demonstrate that their arguments are based on misinterpretations of the literature, and that an asteroid is in fact highly favored over a comet.…”

Section: Introductionmentioning

confidence: 99%

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Matters Arising on "Breakup of a long-period comet as the origin of the dinosaur extinction" by Siraj & Loeb

Desch¹,

Jackson²,

Noviello³

et al. 2021

Preprint

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The recent publication by Siraj & Loeb (2021; Nature Scientific Reports 11, 3803) attempts to revive the debate over whether the Chicxulub impactor was a comet or an asteroid. They calculate that ∼20% of long-period comets impacting Earth will have first been disrupted by passage inside the Sun's Roche limit, generating thousands of fragments, each the needed size of the Chicxulub impactor. This would increase the impact rate of comets by a factor ∼ 15, making them as likely to hit the Earth as an asteroid. They also argue that a comet would be a factor of 10 more likely to match the geochemical constraints, which indicate the Chicxulub impactor was carbonaceous chondrite-like. These conclusions are based on misinterpretations of the literature. Siraj & Loeb [1] overestimate the number of fragments produced during tidal disruption of a comet: tens of fragments are produced, not thousands. They also conflate 'carbonaceous chondrite' with specific types of carbonaceous chondrite, and ignore the evidence of iridium, making comets seem more likely than asteroids to match the Chicxulub impactor, when in fact they likely can be ruled out. Rather than a comet, an asteroidal impactor similar to CM or CR carbonaceous chondrites is strongly favored.

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Breakup of a long-period comet as the origin of the dinosaur extinction

Cited by 24 publications

References 57 publications

Cronomoons: origin, dynamics, and light-curve features of ringed exomoons

Cronomoons: origin, dynamics, and light-curve features of ringed exomoons

Dark Primitive Asteroids Account for a Large Share of K/Pg-Scale Impacts on the Earth

Matters Arising on "Breakup of a long-period comet as the origin of the dinosaur extinction" by Siraj & Loeb

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