The sunward spike of Halley’s comet

Sekanina, Z.; Larson, S. M.; Emerson, G.; Helin, E. F.; Schmidt, R. E.

doi:10.1007/978-3-642-82971-0_116

Cited by 12 publications

(18 citation statements)

References 9 publications

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“…This effect can in principle be either continuous or discrete. The magnitude of the effect is so profound that, if discrete, it must consist of a large number of individual events, because the separation velocities during a cometary splitting are known to be at most only a few meters per second (e.g., Sekanina 1982Sekanina , 2005, much too low to fit ∆B π ≃ 25 • .…”

Section: Of Perihelionmentioning

confidence: 99%

Strong Erosion-Driven Nongravitational Effects in Orbital Motions of the Kreutz Sungrazing System’s Dwarf Comets

Sekanina

Kracht²

2015

ApJ

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We investigate the relationships among the angular orbital elements -the longitude of the ascending node Ω, the inclination i, and the argument of perihelion, ω -of the Kreutz system's faint, dwarf sungrazers observed only with the SOHO/STEREO coronagraphs; their published orbits were derived using a parabolic, purely gravitational approximation. In a plot of i against Ω the bright Kreutz sungrazers (such as C/1843 D1, C/1882 R1, C/1963 R1, etc.) fit a curve of fixed apsidal orientation, whereas the dwarf members are distributed along a curve that makes with the apsidal curve an angle of 15 • . The dwarf sungrazers' perihelion longitude is statistically invariable, but their perihelion latitude increases systematically with Ω. We find that this trend can be explained by a strong erosiondriven nongravitational acceleration normal to the orbit plane, confirmed for several test dwarf Kreutz sungrazers by orbital solutions with nongravitational terms incorporated directly in the equations of motion on a condition of fixed apsidal orientation. Proceeding in three steps, we first apply Marsden et al.'s standard formalism, solving for the normal acceleration only, and eventually relax additional constraints on the nongravitational law and the acceleration's radial and transverse components. The resulting nongravitational accelerations on the dwarf sungrazers exceed the maximum for catalogued comets in nearly-parabolic orbits by up to three orders of magnitude, topping in exceptional cases the Sun's gravitational acceleration! A mass-loss model suggests that the dwarf sungrazers' nuclei fragment copiously and their dimensions diminish rapidly near the Sun, implying the objects' imminent demise shortly before they reach perihelion.

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Section: Of Perihelionmentioning

confidence: 99%

Strong Erosion-Driven Nongravitational Effects in Orbital Motions of the Kreutz Sungrazing System’s Dwarf Comets

Sekanina

Kracht²

2015

ApJ

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“…An unprecedented cometary outburst occurred at 17P/Holmes on UT 2007 October 23, brightening by about one million times within a day (Sekanina 2009;Hsieh et al 2010). Soon after, the comet was enclosed by an envelope composed of high-speed dust grains.…”

Section: Introductionmentioning

confidence: 99%

Detection of Remnant Dust Cloud Associated With the 2007 Outburst of 17p/Holmes

Ishiguro

Sarugaku

Kuroda

et al. 2016

ApJ

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This paper reports a new optical observation of 17P/Holmes one orbital period after the historical outburst event in 2007. We detected not only a common dust tail near the nucleus, but also a long narrow structure that extended along the position angle 274.6 • ± 0.1 • beyond the field of view of the Kiso Wide Field Camera, i.e., >0.2 • eastward and >2.0 • westward from the nuclear position. The width of the structure decreased westward with increasing distance from the nucleus. We obtained the total cross section of the long extended structure in the field of view, C FOV = (2.3 ± 0.5) × 10 10 m 2 . From the position angle, morphology and the mass, we concluded that the long narrow structure consists of materials ejected during the 2007 outburst. On the basis of the dynamical behavior of dust grains in the solar radiation field, we estimated that the long narrow structure would be composed of 1 mm-1 cm grains having an ejection velocity of >50 m s −1 . The velocity was more than one order of magnitude faster than that of millimeter -centimeter grains from typical comets around a heliocentric distance r h of 2.5 AU. We considered that sudden sublimation of a large amount of water ice (≈10 30 mol s −1 ) would be responsible for the high ejection velocity. We finally estimated a total mass of M TOT =(4-8) × 10 11 kg and a total kinetic energy of E TOT =(1-6)×10 15 J for the 2007 outburst ejecta, which are consistent with those of previous studies that conducted soon after the outburst.

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“…A third major outburst practically eliminates the likelihood of this scenario, suggesting that an alternative mechanism causes these unusual periods of activity in 17P/Holmes. The two largest outbursts -those that occurred in 1892 Nov. and 2007 Oct. -both took place approximately five months after 17P/Holmes passed through perihelion at 2.1 AU, suggesting that the activity is thermally-triggered, perhaps with a lag due to the time needed for heat to reach subsurface ice deposits (Sekanina 2008).…”

Section: Introductionmentioning

confidence: 99%

Near-Nucleus Photometry of Outbursting Comet 17p/Holmes

Stevenson¹,

Jewitt²

2012

The Astronomical Journal

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Comet 17P/Holmes underwent the largest cometary outburst in recorded history on UT 2007 Oct. 23, releasing massive quantities of dust and gas. We used the Canada-France-Hawaii telescope to obtain wide-field images of 17P/Holmes on 15 dates over a period of 3 months following the outburst and employ them here to examine the subsequent activity of the nucleus and the nature of the ejecta closest to the nucleus. Through aperture photometry we observed the inner coma (within 2500 km of the nucleus) to fade from an apparent magnitude of 11.7 mag to 17.6 mag, corresponding to absolute magnitudes of 8.1 mag and 12.4 mag, between UT 2007 Nov. 6 and 2008 Feb. 12. A second much smaller outburst occurred on UT 2007 Nov. 12, three weeks after the original outburst,suggesting that the nucleus remained unstable. The surface brightness profile of the inner coma was consistently shallow relative to the expected steady-state profile, and showed a persistent brightness enhancement within ∼ 5000 km of the nucleus. We propose that sublimating ice grains created an ice grain halo around the nucleus, while fragmenting grains were responsible for the shallow surface brightness profile.Subject headings: comets: individual (17P/Holmes)

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The sunward spike of Halley’s comet

Cited by 12 publications

References 9 publications

Strong Erosion-Driven Nongravitational Effects in Orbital Motions of the Kreutz Sungrazing System’s Dwarf Comets

Strong Erosion-Driven Nongravitational Effects in Orbital Motions of the Kreutz Sungrazing System’s Dwarf Comets

Detection of Remnant Dust Cloud Associated With the 2007 Outburst of 17p/Holmes

Near-Nucleus Photometry of Outbursting Comet 17p/Holmes

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