Using Cometary Activity to Trace the Physical and Chemical Evolution of Cometary Nuclei

Meech, К. J.; Svoreň, J.

doi:10.2307/j.ctv1v7zdq5.26

Cited by 103 publications

(96 citation statements)

References 60 publications

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“…Therefore, studying the nitrogen abundance in comets is important for understanding of the conditions under which they were formed in the early solar nebula. It is generally accepted that CO-and CO2-ices were the most common types of ice in the protoplanetary nebula (along with water ice) [86]. The ions CO + and N + which we identified in distant comets, where pristine protoplanetary nebula material remains intact, confirm this conclusion.…”

Section: Spectral Studies Of Distant Cometssupporting

confidence: 80%

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Small Bodies of the Solar System Active at Large Heliocentric Distances: Studies with the 6-Meter Telescope of Sao Ras

Ivanova

2020

Astrophys. Bull.

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A detailed study of comets active at large heliocentric distances (greater than 4 au) which enter the Solar System for the first time and are composed of matter in its elementary, unprocessed state, would help in our understanding of the history and evolution of the Solar System. In particular, contemporary giant planet formation models require the presence of accretion of volatile elements such as neon, argon, krypton, xenon and others, which initially could not survive at the distances where giant planets were formed. Nevertheless, the volatile components could be effectively delivered by the Kuiper-belt and Oort-cloud bodies, which were formed at temperatures below 30 K. This review is dedicated to the results of a multi-year comprehensive study of small bodies of the Solar System showing a comet-like activity at large heliocentric distances. The data were obtained from observations with the 6meter telescope of SAO RAS equipped with multi-mode focal reducers SCORPIO and SCORPIO-2.

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Section: Spectral Studies Of Distant Cometssupporting

confidence: 80%

“…• melting of subsurface ices and formation of supervolatile component solutions, which is accom-panied by significant energy release [86,88];…”

Section: Activity Mechanisms At Large Heliocentric Distancesmentioning

confidence: 99%

Small Bodies of the Solar System Active at Large Heliocentric Distances: Studies with the 6-Meter Telescope of Sao Ras

Ivanova

2020

Astrophys. Bull.

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“…As shown by Ye et al (2019) and confirmed by our work, the actual observed pre-discovery r magnitudes are much closer to the brightness model predicted for a comet that has its activity dominated by CO than H 2 O (Fitzsimmons et al 2019). This is supported by the fact that H 2 O is very weakly sublimating at temperatures 150 K at a heliocentric distance >3.5 au while CO can become volatile much further from the Sun at heliocentric distances exceding 10 to 100 au (Meech & Svoren 2004). However, the pre-discovery photometry may also be compatible with CO 2 -driven activity where CO 2 can become active at > 13 au (Womack et al 2017;Ye et al 2019).…”

Section: Volatile-driven Activitymentioning

confidence: 96%

“…5. The recent rise in brightness suggests a recent turn-on of H 2 O as 2I approached the water ice line at heliocentric distance, r h = 2.5 au on 2019 October 02 UTC where the sublimation rate for H 2 O increases exponentially as the comet approaches the Sun (Meech & Svoren 2004;Jewitt et al 2015).…”

Section: Volatile-driven Activitymentioning

confidence: 99%

“…Using Solar System comets as a guide, the production rate of CN observed in 2I implies a nuclear diameter of ∼6 km. The measured size combined with canonical models describing the brightness of 2I driven by H 2 O or CO sublimation produces very different results versus heliocentric distance, as a body dominated by CO sublimation will be active much farther away from the Sun due to CO's much lower enthalpy of sublimation (Meech & Svoren 2004;Fitzsimmons et al 2019). Therefore, it may be possible to distinguish between different compositional models of 2I by measuring its brightness at different heliocentric distances covering a wide span of times (e.g., Meech 2017;Jewitt et al 2017a).…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations

Bolin,

Lisse,

Kasliwal

et al. 2019

Preprint

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We present visible and near-infrared photometric and spectroscopic observations of interstellar object 2I/Borisov taken from 2019 September 10 to 2019 November 03 using the GROWTH, the APO ARC 3.5 m and the NASA/IRTF 3.0 m combined with post and pre-discovery observations of 2I obtained by ZTF from 2019 March 17 to 2019 May 5. Comparison with imaging of distant Solar System comets shows an object very similar to mildly active Solar System comets with an out-gassing rate of ∼10 27 mol/sec. The photometry, taken in filters spanning the visible and NIR range shows a gradual brightening trend of ∼ 0.03 mags/day since 2019 September 10 UTC for a reddish object becoming neutral in the NIR. The lightcurve from recent and pre-discovery data reveals a brightness trend suggesting the recent onset of significant H 2 O sublimation with the comet being active with super volatiles such as CO at heliocentric distances >6 au consistent with its extended morphology. Using the advanced capability to significantly reduce the scattered light from the coma enabled by highresolution NIR images from Keck adaptive optics taken on 2019 October 04, we estimate a diameter of 2I's nucleus of 3 km, though the true size is likely ∼2-3 times smaller due to the incomplete removal of dust from the measurement. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the ISO size-distribution resulting in a slope of -2.9, similar to Solar System comets, though the true slope is likely significantly steeper due to small numbers.

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Dynamics of HVECs emitted from comet C/2011 L4 as observed by STEREO

et al. 2015

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High-quality white-light images from the Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) HI-1 telescope on board STEREO-B reveal high-velocity evanescent clumps (HVECs) expelled from the coma of the C/2011 L4 (Pan-STARRS) comet. The observations were recorded around the comet's perihelion (i.e., ∼0.3 AU) during the period 9-16 March 2013. Animated images provide evidence of highly dynamic ejecta moving near radially in the antisunward direction. The bulk speed of the clumps at their initial detection in the HI1-B images range from 200 to 400 km s −1 followed by an appreciable acceleration up to speeds of 450-600 km s −1 , which are typical of slow to intermediate solar wind speeds. The clump velocities do not exceed these limiting values and seem to reach a plateau. The images also show that the clumps do not expand as they propagate. The white-light images do not provide direct insight into the composition of the expelled clumps, which could potentially be composed of fine, submicron dust particles, neutral atoms and molecules, and/or ionized atomic/molecular cometary species. Although solar radiation pressure plays a role in accelerating and size sorting of small dust grains, it cannot accelerate them to velocities >200 km s −1 in the observed time interval of a few hours and distance of <10 6 km. Further, order of magnitude calculations show that ionized single atoms or molecules accelerate too quickly compared to observations, while dust grains micron sized or larger accelerate too slowly. We find that neutral Na, Li, K, or Ca atoms with > 50 could possibly fit the observations. Just as likely, we find that an interaction with the solar wind and the heliospheric magnetic field can cause the observed clump dynamical evolution, accelerating them quickly up to solar wind velocities. We thus speculate that the HVECs are composed of charged particles (dust particles) or neutral atoms accelerated by radiation pressure at > 50 values. In addition, the data suggest that clump ejecta initially move along near-radial, bright structures, which then separate into HVECs and larger dust grains that steadily bend backward relative to the comet's orbital motion due to the effects of solar radiation and gravity. These structures gradually form new striae in the dust tail. The near-periodic spacing of the striae may be indicative of outgassing activity modulation due to the comet nucleus' rotation. It is, however, unclear whether all striae are formed as a result of this process.

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Using Cometary Activity to Trace the Physical and Chemical Evolution of Cometary Nuclei

Cited by 103 publications

References 60 publications

Small Bodies of the Solar System Active at Large Heliocentric Distances: Studies with the 6-Meter Telescope of Sao Ras

Small Bodies of the Solar System Active at Large Heliocentric Distances: Studies with the 6-Meter Telescope of Sao Ras

Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations

Dynamics of HVECs emitted from comet C/2011 L4 as observed by STEREO

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