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Thread: Disintegrating Planets - some recent news

  1. #91
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    And an old thread created on CQ that directly related to planetary engulfment and stellar pollution as a result, regarding van Maanen 2, the nearby white dwarf.

    https://forum.cosmoquest.org/showthr...anetary-system
    Do good work. —Virgil Ivan "Gus" Grissom

  2. #92
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    Quote Originally Posted by Noclevername View Post
    The name Dagon was old long before Lovecraft was ever born. https://en.wikipedia.org/wiki/Dagon
    It is still wise for us not to tempt the Ancient Ones. However, we did name a big section of Pluto after Cthulhu, I believe.
    Do good work. —Virgil Ivan "Gus" Grissom

  3. #93
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    Gas giant will be engulfed by its red-giant star in 800 million years.

    https://arxiv.org/abs/2005.00272
    TESS Asteroseismic Analysis of the Known Exoplanet Host Star HD 222076
    Chen Jiang, Timothy R. Bedding, Keivan G. Stassun, Dimitri Veras, Enrico Corsaro, Derek L. Buzasi, Przemysław Mikołajczyk, Qian-sheng, Zhang, Jian-wen, Ou, Tiago L. Campante, Thaíse S. Rodrigues, Benard Nsamba, Diego Bossini, Stephen R. Kane, Jia Mian Joel Ong, Mutlu Yıldız, Zeynep Çeiik Orhan, Sibel Örtel, Tao Wu, Xinyi Zhang, Tanda Li, Sarbani Basu, Margarida S. Cunha, Jřrgen Christensen-Dalsgaard, William J. Chaplin
    [Submitted on 1 May 2020]
    The Transiting Exoplanet Survey Satellite (TESS) is an all-sky survey mission aiming to search for exoplanets that transit bright stars. The high-quality photometric data of TESS are excellent for the asteroseismic study of solar-like stars. In this work, we present an asteroseismic analysis of the red-giant star HD 222076 hosting a long-period (2.4 yr) giant planet discovered through radial velocities. Solar-like oscillations of HD 222076 are detected around 203 μHz by TESS for the first time. Asteroseismic modeling, using global asteroseismic parameters as input, yields a determination of the stellar mass (M⋆ = 1.12 ± 0.12 M⊙), radius (R⋆ = 4.34 ± 0.21R⊙), and age (7.4 ± 2.7Gyr), with precisions greatly improved from previous studies. The period spacing of the dipolar mixed modes extracted from the observed power spectrum reveals that the star is on the red-giant branch burning hydrogen in a shell surrounding the core. We find that the planet will not escape the tidal pull of the star and be engulfed into it within about 800 Myr, before the tip of the red-giant branch is reached.
    Do good work. —Virgil Ivan "Gus" Grissom

  4. #94
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    Brief description of a blistering-hot disintegrating gas giant, our pal KELT-9b.

    https://ui.adsabs.harvard.edu/abs/20...4727K/abstract
    Eclipses of a Scalding Hot Planet
    Kohler, Susanna
    AAS Nova Highlight, 25 Jan 2019, id.4727
    Pub Date: February 2019
    What's the atmosphere like on the hottest planet weve ever discovered? A new study suggests this toasty world may also be cloudless. More than two decades ago, the discovery of the first hot Jupiters--gas giant exoplanets that orbit extremely close to their host stars--signaled that other solar systems may host very different planets than our own. Since then, we've discovered a whole zoo of unusual planets including ever hotter Jupiters. Thus far, Kelt-9b holds the record. This scalding giant orbits once every 1.49 days while its 10,000-K host blasts it with ultraviolet radiation. Its dayside temperature (Kelt-9b is tidally locked, so the same side always faces its host) is somewhere between 4,000 and 4,600 K, which is hotter than many stars. Under these extreme conditions, what is Kelt-9bs atmosphere like? Is it similar to its slightly cooler hot-Jupiter cousins? Or do the extreme temperatures lead to unusual features?
    Do good work. —Virgil Ivan "Gus" Grissom

  5. #95
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    Gaseous iron discovered in scalding atmosphere of our buddy, KELT-9b.

    https://phys.org/news/2020-05-iron-e...tmosphere.html
    Do good work. —Virgil Ivan "Gus" Grissom

  6. #96
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    Some white dwarfs with metal pollution have planetary bodies near their tidal disruption limits. How did this happen?

    https://arxiv.org/abs/2005.05977
    High-eccentricity migration of planetesimals around polluted white dwarfs
    Christopher E. O'Connor, Dong Lai
    [Submitted on 12 May 2020]
    Several white dwarfs with atmospheric metal pollution have been found to host small planetary bodies (planetesimals) orbiting near the tidal disruption radius. We study the physical properties and dynamical origin of these bodies under the hypothesis that they underwent high-eccentricity migration from initial distances of several astronomical units. We examine two plausible mechanisms for orbital migration and circularization: tidal friction and ram-pressure drag in a compact disc. For each mechanism, we derive general analytic expressions for the evolution of the orbit that can be rescaled for various situations. We identify the physical parametres that determine whether a planetesimal's orbit can circularize within the appropriate time-scale and constrain these parametres based on the properties of the observed systems. For tidal migration to work, an internal viscosity similar to that of molten rock is required, and this may be naturally produced by tidal heating. For disc migration to operate, a minimal column density of the disc is implied; the inferred total disc mass is consistent with estimates of the total mass of metals accreted by polluted WDs.
    Do good work. —Virgil Ivan "Gus" Grissom

  7. #97
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    The disintegrating main-belt asteroid 6478 Gault, tail and all, are the subject of this paper.

    https://arxiv.org/abs/2005.07270
    Broadband photometry of asteroid 6478 Gault: activity and morphology
    S. Borysenko, A. Baransky, A. Simon, V. Vasylenko
    [Submitted on 14 May 2020]
    We present the results of short observational program for asteroid 6478 Gault with using of V and R Johnson filters realized at the Kyiv Comet Station during January-April 2019. Color indices and distribution of brightness in the comet-like tail were calculated. We made a comparative analysis of circumstances of the asteroid 6478 Gault activity with others morphologically similar active Main Belt asteroids.
    Do good work. —Virgil Ivan "Gus" Grissom

  8. #98
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    So many ways to crumble: planets of white-dwarf stars.

    https://arxiv.org/abs/2006.03073
    The lifetimes of planetary debris discs around white dwarfs
    Dimitri Veras, Kevin Heng
    [Submitted on 4 Jun 2020]
    The lifetime of a planetary disc which orbits a white dwarf represents a crucial input parameter into evolutionary models of that system. Here we apply a purely analytical formalism to estimate lifetimes of the debris phase of these discs, before they are ground down into dust or are subject to sublimation from the white dwarf. We compute maximum lifetimes for three different types of white dwarf discs, formed from (i) radiative YORP breakup of exo-asteroids along the giant branch phases at 2-100 au, (ii) radiation-less spin-up disruption of these minor planets at ∼ 1.5−4.5 R⊙, and (iii) tidal disruption of minor or major planets within about 1.3 R⊙. We display these maximum lifetimes as a function of disc mass and extent, constituent planetesimal properties, and representative orbital excitations of eccentricity and inclination. We find that YORP discs with masses up to 10^24 kg live long enough to provide a reservoir of surviving cm-sized pebbles and m- to km-sized boulders that can be perturbed intact to white dwarfs with cooling ages of up to 10 Gyr. Debris discs formed from the spin or tidal disruption of these minor planets or major planets can survive in a steady state for up to respectively 1 Myr or 0.01 Myr, although most tidal discs would leave a steady state within about 1 yr. Our results illustrate that dust-less planetesimal transit detections are plausible, and would provide particularly robust evolutionary constraints. Our formalism can easily be adapted to individual systems and future discoveries.
    Do good work. —Virgil Ivan "Gus" Grissom

  9. #99
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    Want to REALLY disintegrate your planet or planetoid? Crash it into a magnetar. This may have happened in our Galaxy.

    https://arxiv.org/abs/2006.04601
    FRB 200428: an Impact between an Asteroid and a Magnetar?
    Jin-Jun Geng, Bing Li, Long-Biao Li, Shao-Lin Xiong, Rolf Kuiper, Yong-Feng Huang
    [Submitted on 8 Jun 2020]
    A fast radio burst was recently detected to be associated with a hard X-ray burst from the Galactic magnetar SGR 1935+2154. Scenarios involving magnetars for FRBs are hence highly favored. In this work, we suggest that the impact between an asteroid and a magnetar could explain such a detection. According to our calculations, an asteroid of mass 10^20 g will be disrupted at 7 × 10^9 cm when approaching the magnetar, the accreted material will flow along the magnetic field lines at Alfvén radius ∼ 10^7 cm. After falling onto the magnetar surface, an instant accretion column will be formed, producing a Comptonized X-ray burst and an FRB in the magnetosphere. We show that all the observational features could be interpreted self-consistently in our scenario. The quasi-periodic oscillations in this specific X-ray burst may help to verify our scenario.
    Do good work. —Virgil Ivan "Gus" Grissom

  10. #100
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    An evaporating planet around a hot white dwarf? Or some other form of planetary wreckage?

    https://arxiv.org/abs/2006.10806
    [Submitted on 18 Jun 2020]
    Optical detection of the 1.1-day variability at the white dwarf GD 394 with TESS
    David J. Wilson, J. J. Hermes, Boris T. Gaensicke
    Recent discoveries have demonstrated that planetary systems routinely survive the post-main sequence evolution of their host stars, leaving the resulting white dwarf with a rich circumstellar environment. Among the most intriguing of such hosts is the hot white dwarf GD 394, exhibiting a unique 1.150±0.003 d flux variation detected in Extreme Ultraviolet Explorer (EUVE) observations in the mid 1990s. The variation has eluded a satisfactory explanation, but hypotheses include channeled accretion producing a dark spot of metals, occultation by a gas cloud from an evaporating planet, or heating from a flux tube produced by an orbiting iron-cored planetesimal. We present observations obtained with the Transiting Exoplanet Survey Satellite (TESS) of GD 394. The space-based optical photometry demonstrates a 0.12±0.01% flux variation with a period of 1.146±0.001 d, consistent with the EUVE period and the first re-detection of the flux variation outside of the extreme ultraviolet. We describe the analysis of the TESS light curve and measurement of the optical variation, and discuss the implications of our results for the various physical explanations put forward for the variability of GD 394.
    Do good work. —Virgil Ivan "Gus" Grissom

  11. #101
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    KELT-9b is the hottest thing around. Literally. No wonder it's boiling off into space.


    https://arxiv.org/abs/2010.00997

    A data-driven approach to constraining the atmospheric temperature structure of KELT-9b

    L. Fossati, D. Shulyak, A. G. Sreejith, T. Koskinen, M. E. Young, P. E. Cubillos, L. M. Lara, K. France, M. Rengel, P. W. Cauley, J. D. Turner, A. Wyttenbach, F. Yan

    Context. Observationally constraining the atmospheric temperature-pressure (TP) profile of exoplanets is an important step forward for improving planetary atmosphere models, further enabling one to place the detection of spectral features and the measurement of atomic and molecular abundances through transmission and emission spectroscopy on solid ground. Aims. The aim is to constrain the TP profile of the ultra-hot Jupiter KELT-9b by fitting synthetic spectra to the observed Hα and Hβ lines and identify why self-consistent planetary TP models are unable to fit the observations. Methods. We construct 126 one-dimensional TP profiles varying the lower and upper atmospheric temperatures, as well as the location and gradient of the temperature rise. For each TP profile, we compute transmission spectra of the Hα and Hβ lines employing the Cloudy radiative transfer code, which self-consistently accounts for non-local thermodynamic equilibrium (NLTE) effects. Results. The TP profiles leading to best fit the observations are characterised by an upper atmospheric temperature of 10,000-11,000 K and by an inverted temperature profile at pressures higher than 10^4 bar. We find that the assumption of local thermodynamic equilibrium (LTE) leads to overestimate the level population of excited hydrogen by several orders of magnitude, and hence to significantly overestimate the strength of the Balmer lines. The chemical composition of the best fitting models indicate that the high upper atmospheric temperature is most likely driven by metal photoionisation and that FeII and FeIII have comparable abundances at pressures lower than 10^6 bar, possibly making the latter detectable. Conclusions. Modelling the atmospheres of ultra-hot Jupiters requires one to account for metal photoionisation. [abridged]
    Do good work. —Virgil Ivan "Gus" Grissom

  12. #102
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    Two recent papers on disintegrating exoplanets.


    https://arxiv.org/abs/2009.05525

    Comet-like tails of disintegrating exoplanets explained by escaping outflows emanated from the permanent nightside: day-side versus night-side escape

    Wanying Kang, Feng Ding, Robin Wordsworth, Sara Seager

    Ultra-hot disintegrating exoplanets have been detected with tails trailing behind and/or shooting ahead of them. These tails are believed to be made of dusts that are carried upward by the supersonic flow escaping the planet's gravity field from the fiercely heated permanent day-side. Conserving angular momentum, this day-side escape flux would lead the planet in orbit. In order to explain the trailing tails in observation, radiation pressure, a repulsive force pushing the escape flow away from the host star is considered to be necessary.

    We here investigate whether escape could occur on the night-side as the escape flow is deflected by the pressure gradient force. We demonstrate in an idealized framework that escape flux from the night-side could dominate that from the day-side; and the former may naturally explain the commonly-observed trailing tails based on angular momentum conservation, without the need to invoke radiation pressure, which has previously been thought to be the key. We also find analytical approximations for both dayside and nightside escape fluxes, which may be applied to study planetary evolution of disintegrating planets and to infer planetary sizes from observations of the properties of their dusty tails.

    ======

    https://arxiv.org/abs/2010.12667

    A Characterization of the Circumstellar Gas around WD 1124-293 using Cloudy

    Amy Steele, John Debes, Siyi Xu, Sherry Yeh, Patrick Dufour

    Between 30 - 50% of white dwarfs (WDs) show heavy elements in their atmospheres. This "pollution" is thought to arise from the accretion of planetesimals perturbed by outer planet(s) to within the WD's tidal disruption radius. A small fraction of these WDs show either emission or absorption from circumstellar (C-S) gas. The abundances of metals in the photospheres of WDs with C-S gas are mostly similar to the bulk composition of the Earth. The C-S component arises from gas produced through collisions and/or the sublimation of disintegrating planetesimals.
    Do good work. —Virgil Ivan "Gus" Grissom

  13. #103
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    Disintegrating and destroyed planet debris around white dwarfs.


    https://arxiv.org/abs/2011.12299

    Rapid destruction of planetary debris around WDs through wind erosion

    Mor Rozner, Dimitri Veras, Hagai B. Perets

    The discovery of numerous debris disks around white dwarfs (WDs), gave rise to extensive study of such disks and their role in polluting WDs, but the formation and evolution of these disks is not yet well understood. Here we study the role of wind erosion in the evolution of solids in WD debris disks. Wind erosion is a destructive process that plays a key role in shaping the properties and size-distribution of planetesimals, boulders and pebbles in gaseous protoplanetary disks. Our analysis of wind erosion in WD debris disks shows it can also play an important role in these environments. We study the effects of wind erosion under different conditions of the disk, and its erosive effect on planetesimals and boulders of different sizes. We find that solid bodies smaller than ∼5km will be eroded within the short disk lifetime. We compare the role of wind erosion in respect to other destructive processes such as collisional fragmentation and thermal ablation. We find that wind erosion is the dominant destructive process for objects with radius ≲103cm and at distances ≲0.6R⊙ from the WD. Thereby, wind erosion constitutes the main destructive pathway linking fragmentational collisions operating on large objects with sublimation of the smallest objects and Poynting-Robertson drag, which leads to the accretion of the smallest particles onto the photosphere of WDs, and the production of polluted WDs.
    Do good work. —Virgil Ivan "Gus" Grissom

  14. #104
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    An hot Jupiter in a decaying orbit, confirmed by TESS.

    https://arxiv.org/abs/2012.02211

    Decaying Orbit of the Hot Jupiter WASP-12b: Confirmation with TESS Observations

    Jake D. Turner, Andrew Ridden-Harper, Ray Jayawardhana

    Theory suggests that the orbits of some close-in giant planets should decay due to tidal interactions with their host stars. To date, WASP-12b is the only hot Jupiter reported to have a decaying orbit, at a rate of 29±2 msec year−1. We analyzed data from NASA's Transiting Exoplanet Survey Satellite (TESS) to verify that WASP-12b's orbit is indeed changing. We find that the TESS transit and occultation data are consistent with a decaying orbit with an updated period of 1.091420090±0.000000041 days and a decay rate of 32.53±1.62 msec year−1. We find an orbital decay timescale of τ = P/|P˙| = 2.90±0.14 Myr. If the observed decay results from tidal dissipation, the modified tidal quality factor is Q'⋆ = 1.39±0.15 ×105, which falls at the lower end of values derived for binary star systems and hot Jupiters. Our result highlights the power of space-based photometry for investigating the orbital evolution of short-period exoplanets.
    Do good work. —Virgil Ivan "Gus" Grissom

  15. #105
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    More on the doomed giant planet WASP-12b.

    https://www.sciencealert.com/one-of-...-a-fiery-death
    Do good work. —Virgil Ivan "Gus" Grissom

  16. #106
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    Two papers on white dwarfs that ate their disintegrated planets, leaving lithium and hydrogen behind.

    =====

    https://arxiv.org/abs/2012.12900

    Lithium pollution of a white dwarf records the accretion of an extrasolar planetesimal

    Benjamin C. Kaiser, J. Christopher Clemens, Simon Blouin, Patrick Dufour, Ryan J. Hegedus, Joshua S. Reding, Antoine Bédard

    Tidal disruption and subsequent accretion of planetesimals by white dwarfs can reveal the elemental abundances of rocky bodies in exoplanetary systems. Those abundances provide information on the composition of the nebula from which the systems formed, analogous to how meteorite abundances inform our understanding of the early Solar System. We report the detection of Li, Na, K and Ca in the atmosphere of the white dwarf Gaia DR2 4353607450860305024, which we ascribe to accretion of a planetesimal. Using model atmospheres, we determine abundance ratios of these elements, and with the exception of Li, they are consistent with meteoritic values in the Solar System. We compare the measured Li abundance to measurements in old stars and to expectations from Big Bang nucleosynthesis.

    -----

    https://arxiv.org/abs/2012.12957

    GD424 -- a helium-atmosphere white dwarf with a large amount of trace hydrogen in the process of digesting a rocky planetesimal

    Paula Izquierdo, Odette Toloza, Boris T. Gänsicke, Pablo Rodríguez-Gil, Jay Farihi, Detlev Koester, Jincheng Guo, Seth Redfield

    The photospheric metal pollution of white dwarfs is now well-established as the signature of the accretion of planetary debris. However, the origin of the trace hydrogen detected in many white dwarfs with helium atmospheres is still debated. Here, we report the analysis of GD424: a metal-polluted, helium-atmosphere white dwarf with a large amount of trace hydrogen. We determined the atmospheric parameters using a hybrid analysis that combines the sensitivity of spectroscopy to the atmospheric composition, log(H/He), with that of photometry and astrometry to the effective temperature, Teff, and surface gravity, logg. The resulting white dwarf mass, radius, and cooling age are MWD=0.77±0.01M⊙, RWD=0.0109±0.0001R⊙, and τcool=215±10 Myr, respectively. We identified and measured the abundances of 11 photospheric metals and argue that the accretion event is most likely either in the increasing or steady state, and that the disrupted planetesimal resembles either CI chondrites or the bulk Earth in terms of its composition. We suggest that the observed 1.33×1022 g of trace hydrogen in GD424 were at least partly acquired through accretion of water-rich planetary debris in an earlier accretion episode.
    Do good work. —Virgil Ivan "Gus" Grissom

  17. #107
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    Metallic oxides in the messed-up atmosphere of our old friend, ultra-hot KELT-9b.

    https://arxiv.org/abs/2101.00469

    The Hubble WFC3 Emission Spectrum of the Extremely-Hot Jupiter, KELT-9b

    Quentin Changeat, Billy Edwards

    Recent studies of ultra hot-Jupiters suggested that their atmospheres could have thermal inversions due to the presence of optical absorbers such as TiO, VO, FeH and other metal hydride/oxides. However, it is expected that these molecules would thermally dissociate at extremely high temperatures, thus leading to featureless spectra in the infrared. KELT-9b, the hottest exoplanet discovered so far, is thought to belong to this regime and host an atmosphere dominated by neutral Hydrogen from dissociation and atomic/ionic species. Here, we analysed the eclipse spectrum obtained using the Hubble Space Telescope's Wide Field Camera 3 (WFC3) and, by utilising the atmospheric retrieval code TauREx3, found that the spectrum is consistent with the presence of molecular species and is poorly fitted by a simple blackbody. In particular, we find that a combination of TiO, VO, FeH and H- provides the best-fit when considering HST, Spitzer and TESS datasets together. Aware of potential biases when combining instruments, we also analysed the HST spectrum alone and found that TiO and VO only were needed in this case. These findings paint a more complex picture of the atmospheres of ultra-hot planets than previously thought.
    Do good work. —Virgil Ivan "Gus" Grissom

  18. #108
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    Tracking planetary remnants in white dwarf stars proves that B-type stars have planets, too.

    https://arxiv.org/abs/2101.01225

    Alkali metals in white dwarf atmospheres as tracers of ancient planetary crusts

    Mark A. Hollands, Pier-Emmanuel Tremblay, Boris T. Gänsicke, Detlev Koester, Nicola P. Gentile-Fusillo

    White dwarfs that accrete the debris of tidally disrupted asteroids provide the opportunity to measure the bulk composition of the building blocks, or fragments, of exoplanets. This technique has established a diversity in compositions comparable to what is observed in the solar system, suggesting that the formation of rocky planets is a generic process. Whereas the relative abundances of lithophile and siderophile elements within the planetary debris can be used to investigate whether exoplanets undergo differentiation, the composition studies carried out so far lack unambiguous tracers of planetary crusts. Here we report the detection of lithium in the atmospheres of four cool (<5,000 K) and old (cooling ages 5-10 Gyr) metal-polluted white dwarfs, where one also displays photospheric potassium. The relative abundances of these two elements with respect to sodium and calcium strongly suggest that all four white dwarfs have accreted fragments of planetary crusts. We detect an infrared excess in one of the systems, indicating that accretion from a circumstellar debris disk is on-going. The main-sequence progenitor mass of this star was 4.8 ± 0.2 M⊙, demonstrating that rocky, differentiated planets may form around short-lived B-type stars.
    Do good work. —Virgil Ivan "Gus" Grissom

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