Asteroids in the Thermal Infrared

Harris, Alan W.; Lagerros, J. S. V.

doi:10.2307/j.ctv1v7zdn4.21

Cited by 125 publications

(62 citation statements)

References 63 publications

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“…2019 LD2 has an absolute magnitude of HV = 12.2±0.8 as listed on JPL Horizons. If we assume this value to represent the absolute magnitude of its nucleus, we can estimate the radius, by assigning an albedo value (see, e.g., Harris & Lagerros, 2002). Typical albedo values for Centaurs, range from 0.05 to 0.112 (Romanishin & Tegler 2018), resulting in 2019 LD2 radius estimates of 11 *3.5…”

Section: Expected Number Of 2019 Ld2-sized Objects In the Gatewaymentioning

confidence: 99%

P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family

Steckloff

Sarid

Volk

et al. 2020

ApJL

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The recently discovered object P/2019 LD2 (by the Asteroid Terrestrial-impact Last Alert System) was initially thought to be a Jupiter Trojan asteroid, until dynamical studies and the appearance of persistent cometary activity revealed that this object is actually an active Centaur. However, the dynamical history, thermal environment, and impact of such environments on the activity of 2019 LD2 are poorly understood. Here we conduct dynamical simulations to constrain its orbital history and resulting thermal environment over the past 3000 yr. We find that 2019 LD2 is currently in the vicinity of a dynamical “Gateway” that facilitates the majority of transitions from the Centaur population into the Jupiter Family of Comets (JFC population). Our calculations show that it is unlikely to have spent significant amounts of time in the inner solar system, suggesting that its nucleus is relatively pristine in terms of physical, chemical, and thermal processing through its history. This could explain its relatively high level of distant activity as a recently activated primordial body. Finally, we find that the median frequency of transition from the Gateway population into the JFC population varies from once every ∼3 yr to less than once every 70 yr, if 2019 LD2's nucleus is ∼1 km in radius or greater than 3 km in radius. Forward modeling of 2019 LD2 shows that it will transition into the JFC population in 2063, representing the first known opportunity to observe the evolution of an active Centaur nucleus as it experiences this population-defining transition.

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Section: Expected Number Of 2019 Ld2-sized Objects In the Gatewaymentioning

confidence: 99%

P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family

Steckloff

Sarid

Volk

et al. 2020

ApJL

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“…propertiesin particular effective radius, R nuc --requires a thermal model, as discussed for asteroids by Lebofsky and Spencer (1989), Spencer et al (1989), Harris and Lagerros (2002), and for comets by Lisse et al (1999Lisse et al ( , 2005; Groussin and Lamy (2003); and Lamy et al (2004). In particular, the thermal regime must be estimated so that an appropriate thermal model can be employed.…”

Section: Thermal Models and Nucleus Size The Conversion From Radiomet...mentioning

confidence: 99%

Spitzer Space TelescopeObservations of the Nucleus of Comet 103P/Hartley 2

Lisse¹,

Fernández²,

Reach³

et al. 2009

PUBL ASTRON SOC PAC

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We have used the Spitzer Space Telescope InfraRed Spectrograph (IRS) 22-m peakup array to observe thermal emission from the nucleus and trail of comet 103P/Hartley 2, the target of NASA's Deep Impact Extended Investigation (DIXI). The comet was observed on UT 2008 August 12 and 13, while the comet was 5.5 AU from the Sun. We obtained two 200-frame sets of photometric imaging over a 2.7-hour period. To within the errors of the measurement, we find no detection of any temporal variation between the two images. The comet showed extended emission beyond a point source in the form of a faint trail directed along the comet's anti-velocity vector. After modeling and removing the trail emission, a NEATM model for the nuclear emission with beaming parameter of 0.95±0.20 indicates a small effective radius for the nucleus of 0.57 ± 0.08 km and low geometric albedo 0.028±0.009 (1). With this nucleus size and a water production rate of 3 x 10 28 molecules s -1 at perihelion (A'Hearn et al. 1995) we estimate that ~100% of the surface area is actively emitting volatile material at perihelion. Reports of emission activity out to ~5 AU (Lowry et al. 2001, Snodgrass et al. 2008) support our finding of a highly active nuclear surface. Compared to Deep Impact's first target, comet 9P/Tempel 1, Hartley 2's nucleus is one-fifth as wide (and about one-hundredth the mass) while producing a similar amount of outgassing at perihelion with about 13 times the active surface fraction. Unlike Tempel 1, it should be highly susceptible to jet driven spin-up torques, and so could be rotating at a much higher frequency. Since the amplitude of nongravitational forces are surprisingly similar for both comets, close to the ensemble average for ecliptic comets (Yeomans et al. 2004), we conclude that comet Hartley 2 must have a much more isotropic pattern of time averaged outgassing from its nuclear surface. Barring a catastrophic breakup or major fragmentation event, the comet should be able to survive up to another 100 apparitions (~700 yrs) at its current rate of mass loss. 18 Pages, 3 Figures, 0 Tables Subject headings: comets: individual (103P/Hartley 2) ---infrared: solar system --techniques: photometric

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“…Thermophysical modeling is required to obtain this information. A thermophysical model (TPM, see Harris and Lagerros 2002;Spencer et al 1989;Lagerros 1996;Emery et al 1998;Delbo' and Tanga 2009, and references therein) describes an asteroid as a polyhedron made by a mesh of planar facets. The temperature of each facet is determined by numerically solving the one-dimensional heat diffusion equation into the subsurface with boundary conditions given by the diurnal variable illumination and by the energy irradiated away by each facet at the surface, and by setting the heat flow at the deepest subsurface element equal to zero.…”

Section: Thermal Properties Of Neosmentioning

confidence: 99%

Heating of near-Earth objects and meteoroids due to close approaches to the Sun

Marchi¹,

Delbò²,

Morbidelli³

et al. 2009

Monthly Notices of the Royal Astronomical Society

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It is known that near-Earth objects (NEOs) during their orbital evolution may often undergo close approaches to the Sun. Indeed it is estimated that up to similar to 70 per cent of them end their orbital evolution colliding with the Sun. Starting from the present orbital properties, it is possible to compute the most likely past evolution for every NEO, and to trace its distance from the Sun. We find that a large fraction of the population may have experienced in the past frequent close approaches, and thus, as a consequence, a considerable Sun-driven heating, not trivially correlated to the present orbits. The detailed dynamical behaviour, the rotational and the thermal properties of NEOs determine the exact amount of the resulting heating due to the Sun. In the present paper, we discuss the general features of the process, providing estimates of the surface temperature reached by NEOs during their evolution. Moreover, we investigate the effects of this process on meteor-size bodies, analysing possible differences with the NEO population. We also discuss some possible effects of the heating which can be observed through remote sensing by ground-based surveys or space missions

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Asteroids in the Thermal Infrared

Cited by 125 publications

References 63 publications

P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family

P/2019 LD2 (ATLAS): An Active Centaur in Imminent Transition to the Jupiter Family

Spitzer Space TelescopeObservations of the Nucleus of Comet 103P/Hartley 2

Heating of near-Earth objects and meteoroids due to close approaches to the Sun

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