Small-scale dust structures in Halley's coma

Oberč, P.

doi:10.1016/j.icarus.2004.05.005

Cited by 8 publications

(4 citation statements)

References 41 publications

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“…Tuzzolino et al (2004) and Green et al (2004Green et al ( , 2007 reported that the Stardust Flux Monitor measurements of comet Wild 2 contained fine-scale structure that was best understood by particle fragmentation. Similar structure events were detected in the dust outflows of Halley by the VEGA instruments (Oberc 2004). Observations of the material ejected from T1 immediately after the DI event are also consistent with extended de-aggregagtion of the ejected material (Lisse et al 2006;Keller et al 2007).…”

Section: Particle Size and Dust Masssupporting

confidence: 75%

INFRARED SPECTROSCOPY OF COMET 73P/SCHWASSMANN-WACHMANN 3 USING THESPITZER SPACE TELESCOPE

Sitko

Lisse

Kelley

et al. 2011

The Astronomical Journal

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We have used the Spitzer Space Telescope Infrared Spectrograph (IRS) to observe the 5-37 µm thermal emission of comet 73P/Schwassmann-Wachmann 3 (SW3), components B and C. We obtained low spectral resolution (R∼100) data over the entire wavelength interval, along with images at 16 and 22 µm. These observations provided an unprecedented opportunity to study nearly pristine material from the surface and what was until recently the interior of an ecliptic comet -cometary surface having experienced only two prior perihelion passages, and including material that was totally fresh. The spectra were modeled using a variety of mineral types including both amorphous and crystalline components. We find that the degree of silicate crystallinity, ∼35%, is somewhat lower than most other comets with strong emission features, while its abundance of amorphous carbon is higher. Both suggest that SW3 is among the most chemically primitive solar system objects yet studied in detail, and that it formed earlier or farther from the sun than the bulk of the comets studied so far. The similar dust compositions of the two fragments suggests that these are not mineralogically heterogeneous, but rather uniform throughout their volumes. The best-fit particle size distribution for SW3B has a form dn/da∼a −3.5 , close to that expected for dust in collisional equilibrium, while that for SW3C has dn/da∼a −4.0 , as seen mostly in active comets with strong directed jets such as C/1995 O1 Hale-Bopp. The total mass of dust in the comae plus nearby tail, extrapolated from to the field of view of the IRS peakup image arrays, is 3-5 x 10 8 kg for B and 7-9 x 10 8 1 Guest observer, Spitzer Space Telescope -3kg for C. Atomic abundances derived from the spectral models indicates a depletion of O compared to solar photospheric values, despite the inclusion of water ice and gas in the models. Atomic C may be solar or slightly sub-solar, but its abundance is complicated by the potential contribution of spectrally featureless mineral species to the portion of the spectra most sensitive to the derication of the C abundance. We find a relatively high bolometric albedo, ∼0.13 for the dust, considering the large amount of dark carbonaceous material, but consistent with the presence of abundant small particles and strong emission features.

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Section: Particle Size and Dust Masssupporting

confidence: 75%

INFRARED SPECTROSCOPY OF COMET 73P/SCHWASSMANN-WACHMANN 3 USING THESPITZER SPACE TELESCOPE

Sitko

Lisse

Kelley

et al. 2011

The Astronomical Journal

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“…CHON is a frequently used component in planet formation models (e.g., Pollack et al 1996; Helled et al 2008). The composition of CHON is set to be similar to that of the grains in Comet Halley’s coma (Oberc 2004). CHON vaporisation temperature is higher than that of water but is still rather low, K for the range of gas pressures appropriate for the interiors of pre-collapse fragments 2 .…”

Section: Cores In Tidal Downsizing Scenariomentioning

confidence: 99%

Dawes Review 7: The Tidal Downsizing Hypothesis of Planet Formation

Nayakshin

2017

Publ. Astron. Soc. Aust.

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Tidal Downsizing scenario of planet formation builds on ideas proposed by Gerard Kuiper in 1951. Detailed simulations of self-gravitating discs, gas fragments, dust grain dynamics, and planet evolutionary calculations are summarised here and used to build a predictive population synthesis. A new interpretation of exoplanetary and debris disc data, the Solar System's origins, and the links between planets and brown dwarfs is offered. Tidal Downsizing predicts that presence of debris discs, sub-Neptune mass planets, planets more massive than ∼5 Jupiter masses and brown dwarfs should not correlate strongly with the metallicity of the host. For gas giants of ∼Saturn to a few Jupiter mass, a strong host star metallicity correlation is predicted only inwards of a few AU from the host. Composition of massive cores is predicted to be dominated by rock rather than ices. Debris discs made by Tidal Downsizing have an innermost edge larger than about 1 au, have smaller total masses and are usually in a dynamically excited state. Planet formation in surprisingly young or very dynamic systems such as HL Tau and Kepler-444 may be a signature of Tidal Downsizing. Open questions and potential weaknesses of the hypothesis are pointed out.Keywords: accretion, accretion disks -planets and satellites: formation -protoplanetary disks -planet disk interactions -stars: formation PrefaceThe Dawes Reviews are substantial reviews of topical areas in astronomy, published by authors of international standing at the invitation of the PASA Editorial Board. The reviews recognise William Dawes (1762-1836), second lieutenant in the Royal Marines and the astronomer on the First Fleet. Dawes was not only an accomplished astronomer, but spoke five languages, had a keen interest in botany, mineralogy, engineering, cartography, and music, compiled the first Aboriginal-English dictionary, and was an outspoken opponent of slavery.

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“…Sublimation was considered as the explanation for the deviation of the Halley brightness profile from a simple 1/ρ law by Tozzi et al (2004). Organics may hold grain aggregates together until the organics vaporize (Oberc 2004(Oberc , 2007. In this section, we consider the effects of a simple breakup model for our images at in 2006 May, without reference to the actual mechanism of fragmentation.…”

Section: Grain Fragmentationmentioning

confidence: 99%

Evidence of Fragmenting Dust Particles From Near-Simultaneous Optical and Near-Infrared Photometry and Polarimetry of Comet 73p/Schwassmann-Wachmann 3

Jones

Stark

Woodward

et al. 2008

The Astronomical Journal

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We report imaging polarimetry of segments B and C of the Jupiter-family comet 73P/Schwassmann-Wachmann 3 in the I and H bandpasses at solar phase angles of approximately 35• and 85• . The level of polarization was typical for active comets, but larger than expected for a Jupiter-family comet. The polarimetric color was slightly red (δP /δλ = +1.2 ± 0.4) at a phase angle of ∼35• and either neutral or slightly blue at a phase angle of ∼85 • . Observations during the closest approach from 2006 May 11-13 achieved a resolution of 35 km at the nucleus. Both segments clearly depart from a 1/ρ surface brightness for the first 50-200 km from the nucleus. Simulations of radiation-driven dust dynamics can reproduce some of the observed coma morphology, but only with a wide distribution of initial dust velocities (at least a factor of 10) for a given grain radius. Grain aggregate breakup and fragmentation are able to reproduce the observed profile perpendicular to the Sun-comet axis, but fit the observations less well along this axis (into the tail). The required fragmentation is significant, with a reduction in the mean grain aggregate size by about a factor of 10. A combination of the two processes could possibly explain the surface brightness profile of the comet.

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Small-scale dust structures in Halley's coma

Cited by 8 publications

References 41 publications

INFRARED SPECTROSCOPY OF COMET 73P/SCHWASSMANN-WACHMANN 3 USING THESPITZER SPACE TELESCOPE

INFRARED SPECTROSCOPY OF COMET 73P/SCHWASSMANN-WACHMANN 3 USING THESPITZER SPACE TELESCOPE

Dawes Review 7: The Tidal Downsizing Hypothesis of Planet Formation

Evidence of Fragmenting Dust Particles From Near-Simultaneous Optical and Near-Infrared Photometry and Polarimetry of Comet 73p/Schwassmann-Wachmann 3

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