Evolution and detectability of comet clouds during post-main-sequence stellar evolution

Stern, S. A.; Shull, J. M.; Brandt, J. C.

doi:10.1038/345305a0

Cited by 42 publications

(50 citation statements)

References 21 publications

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“…The study by Stern et al (1990) dates back to the era before exo-planet discoveries. The authors suggest that some volatile emissions commonly observed around post main sequence stars can be explained by sublimation of large reservoirs of comets during the high luminosity stellar evolution phases following the main sequence, hence indirectly supporting the existence of exo-comets, and by extension, planetary systems.…”

Section: Previous Studiesmentioning

confidence: 99%

“…First, we reevaluate, based on a new and improved model, how much water can survive the high luminosity RGB and AGB stellar evolutionary phases. Early work on this problem includes the seminal studies of Stern et al (1990) and Jura & Xu (2010), however the models they use have various limitations that need to be addressed. Based on our findings, we then discuss different potential explanations for the scarcity of water detections.…”

Section: Introductionmentioning

confidence: 99%

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Post-Main Sequence Evolution of Icy Minor Planets: Implications for Water Retention and White Dwarf Pollution

Malamud

Perets

2016

ApJ

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Most observations of polluted white dwarf atmospheres are consistent with accretion of water depleted planetary material. Among tens of known cases, merely two cases involve accretion of objects that contain a considerable mass fraction of water. The purpose of this study is to investigate the relative scarcity of these detections. Based on a new and highly detailed model, we evaluate the retention of water inside icy minor planets during the high luminosity stellar evolution that follows the main sequence. Our model fully considers the thermal, physical, and chemical evolution of icy bodies, following their internal differentiation as well as water depletion, from the moment of their birth and through all stellar evolution phases preceding the formation of the white dwarf. We also account for different initial compositions and formation times. Our results differ from previous studies, that have either underestimated or overestimated water retention. We show that water can survive in a variety of circumstances and in great quantities, and therefore other possibilities are discussed in order to explain the infrequency of water detections. We predict that the sequence of accretion is such that water accretes earlier, and more rapidly than the rest of the silicate disk, considerably reducing the chance of its detection in H-dominated atmospheres. In He-dominated atmospheres, the scarcity of water detections could be observationally biased. It implies that the accreted material is typically intrinsically dry, which may be the result of inside-out depopulation sequence of minor planets.

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Section: Previous Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Post-Main Sequence Evolution of Icy Minor Planets: Implications for Water Retention and White Dwarf Pollution

Malamud

Perets

2016

ApJ

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“…Understanding how water survive inside minor planets as a function of their intrinsic characteristics, is a necessary first step in beginning to understand the origin and nature of polluting planetary material. The seminal work of Stern et al (1990) introduced a simple sublimation model that considered the initial orbital distance and size of minor planets as they evolve around a post-main-sequence 1 M ⊙ star. Jura & Xu (2010) considered a more advanced model, taking into account conductive heat transport to the interior, and also the minor planets' orbital expansion during the post-main-sequence stellar evolution of a 1 M ⊙ and 3 M ⊙ host stars.…”

Section: Introductionmentioning

confidence: 99%

Post-main-sequence Evolution of Icy Minor Planets. III. Water Retention in Dwarf Planets and Exomoons and Implications for White Dwarf Pollution

Malamud

Perets

2017

ApJ

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Studies suggest that the pollution of white dwarf (WD) atmospheres arises from the accretion of minor planets, but the exact properties of polluting material, and in particular the evidence for water in some cases are not yet understood. Previous works studied the water retention in minor planets around main-sequence and evolving host stars, in order to evaluate the possibility that water survives inside minor planets around WDs. However, all of these studies focused on small, comet-sized to moonlet-sized minor planets, when the inferred mass inside the convection zones of He-dominated WDs could actually also be compatible with much more massive minor planets. In this study we therefore explore for the first time, the water retention inside exoplanetary dwarf planets, or moderate-sized moons, with radii of the order of hundreds of kilometres. We now cover nearly the entire potential mass range of minor planets. The rest of the parameter space considered in this study is identical to that of our previous study, and also includes multiple WD progenitor star masses. We find that water retention in more massive minor planets is still affected by the mass of the WD progenitor, however not as much as when small minor planets were considered. We also find that water retention is now almost always greater than zero. On average, the detected water fraction in He-dominated WD atmospheres should be at least 5%, irrespective of the assumed initial water composition, if it came from a single accretion event of an icy dwarf planet or moon. This finding also strengthens the possibility of WD habitability. To finalize our previous and current findings, we provide a code which may be freely used as a service to the community. The code calculates ice and water retention by interpolation, spanning the full mass range of both minor planets and their host stars.

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“…This is as expected, since dust at Oort cloud distances will be very cold, and radiation pressure and collisions with interstellar dust and gas should rapidly sweep fine dust from the comet clouds (Stern, 1990). Stern et al (1990b) have also proposed searching for Oort clouds around red giant stars. These stars are sufficiently luminous that the comets in their Kuiper Belts, if they had them, would be actively sublimating at rates comparable to the gas production rates of comets at 1AU in our own solar system.…”

Section: Extra-solar Oort Clouds and Interstellar Cometsmentioning

confidence: 99%

Dynamical History of the Oort Cloud

Weissman¹

1989

International Astronomical Union Colloquium

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ABSTRACT. Dynamical studies during the past decade have resulted in an almost explosive increase in our understanding of the Oort cloud of comets, which surrounds the solar system. Cometary orbits in the cloud evolve under the complex interaction of stellar, galactic, and giant molecular cloud perturbations, as well as planetary and nongravitational perturbations when the orbits re-enter the planetary region. Evidence has continued to build for a dense, inner Oort cloud of comets which acts as a reservoir to replenish the outer cloud as comets there are stripped away. A ring of comets beyond the orbit of Neptune, which may be the source of the short-period comets, is also likely. Both the estimated number and mass of comets in the Oort cloud have grown such that the total mass may be comparable to the mass of the planets. Temporal variations in the flux of comets from the Oort cloud into the planetary region by a factor of 50% are typical, and by factors of 20 to 200 are possible. The most intense cometary "showers" may have serious implications for biological extinction events on Earth as well as for the impact history of planets and satellite systems. Comets in the Oort cloud are processed by galactic cosmic rays, heated by nearby supernovae, eroded by interstellar dust impacts, and disrupted by mutual collisions (in the inner cloud). A detailed estimate of the Oort cloud's dynamical history is not possible because of the inability to reconstruct the Sun's varying galactic motion over the history of the solar system, and because of uncertainty over where comets actually formed. However, it is likely that a substantial fraction of the original Oort cloud population has been lost to interstellar space. We are approaching the time when Oort clouds around other stars may be detectable, though searches to date have so far been negative.

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Evolution and detectability of comet clouds during post-main-sequence stellar evolution

Cited by 42 publications

References 21 publications

Post-Main Sequence Evolution of Icy Minor Planets: Implications for Water Retention and White Dwarf Pollution

Post-Main Sequence Evolution of Icy Minor Planets: Implications for Water Retention and White Dwarf Pollution

Post-main-sequence Evolution of Icy Minor Planets. III. Water Retention in Dwarf Planets and Exomoons and Implications for White Dwarf Pollution

Dynamical History of the Oort Cloud

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