Yarkovsky-driven impact risk analysis for asteroid (99942) Apophis

Farnocchia, Davide; Chesley, S. R.; Chodas, P. W.; Micheli, M.; Tholen, David J.; Milani, Andrea; Elliott, G. T.; Bernardi, Fabrizio

doi:10.1016/j.icarus.2013.02.020

Cited by 107 publications

(107 citation statements)

References 29 publications

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“…The starting orbital elements were computed using the JPL Planetary and Lunar Ephemerides DE405 and additional perturbations from the 25 massive asteroids. Their masses were taken from Farnocchia et al (2013). We list in Table 5 the physical data of the asteroids that are needed to reproduce perturbations from thermal forces: radius, bulk density, surface density, thermal conductivity, thermal capacity, albedo, infrared emissivity, period, and spin orientation.…”

Section: Initial Datamentioning

confidence: 99%

Differentiation signatures in the Flora region

Oszkiewicz

Kankiewicz

Wlodarczyk³

et al. 2015

A&A

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Context. Most asteroid families are very homogeneous in physical properties. Some show greater diversity, however. The Flora family is the most intriguing of them. The Flora family is spread widely in the inner main belt, has a rich collisional history, and is one of the most taxonomically diverse regions in the main belt. As a result of its proximity to the asteroid (4) Vesta (the only currently known intact differentiated asteroid) and its family, migration between the two regions is possible. This dynamical path is one of the counter arguments to the hypothesis that there may be traces of a differentiated parent body other than Vesta in the inner main belt region. We here investigate the possibility that some of the V-and A-types (commonly interpreted as basaltoids and dunites -parts of the mantle and crust of differentiated parent bodies) in the Flora dynamical region are not dynamically connected to Vesta. Aims. The goal of this study is to investigate asteroids in the Flora dynamical region that may be witness to the differentiation of a parent body other than (4) Vesta. In particular, we aim at predicting which asteroids may be fragments of a differentiated body or bodies (taxonomical V-types). We also investigate their possible dynamical linkage to the nearby Vesta family. Methods. To predict the taxonomic types of asteroids we used the naive Bayes classifier. We studied their dynamical past through numerical integration including gravitational and Yarkovsky forces. Each asteroid was cloned, and average orbital elements were computed at each step. When possible, we used observationally constrained physical parameters for the thermal forces. Results. Most of the asteroids in the Flora region are predicted to originate from the S-complex (around 47.8%). Tens of asteroids with potentially differential origins are identified in the region, including 164 potential V-types. We investigated the dynamical evolution of selected objects to examine possible linkages of selected asteroids with the nearby Vesta family. In addition to the candidate differentiated objects, we also studied the dynamical evolution of those asteroids from the Flora family for which spectroscopic classification exist. In particular, we used all the physical parameters available for asteroid (809) Lundia to show that the asteroid is unlikely to originate in the Vesta region and that it resided on a stable orbit in the Flora dynamical region for at least 80 My. Its observationally constrained prograde rotation shows that asteroid (809) Lundia is unlikely to be a former Vesta family member. Conclusions. We found that the V-type candidates are plentiful in the Flora dynamical region. Dynamical investigations of selected objects showed that some of these objects were likely not connected to asteroid (4) Vesta and its family for at least 100 My. This adds another piece of evidence to the hypothesis that there are multiple differentiated parent bodies.

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Section: Initial Datamentioning

confidence: 99%

Differentiation signatures in the Flora region

Oszkiewicz

Kankiewicz

Wlodarczyk³

et al. 2015

A&A

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“…With the available data, it is known that Apophis will have an extremely close approach on April 13, 2029, at 5.7 Earth radii from the Earth's center, just below the altitude of geosynchronous Earth satellites; by means of a statistical analysis, Farnocchia et al (2013) find an impact probability greater than 10 −6 for an impact in 2068.…”

Section: Introductionmentioning

confidence: 99%

GTC/CanariCam observations of (99942) Apophis

Licandro

Müller

Álvarez

et al. 2015

A&A

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Context. The potentially hazardous asteroid (PHA) (99942) Apophis is one of the most remarkable near-Earth asteroids (NEA) in terms of impact hazard. A good determination of its surface thermal inertia is very important in order to evaluate the Yarkovsky effect on its orbital evolution. Aims. We present thermal infrared observations obtained on January 29, 2013, with CanariCam mid-infrared camera/spectrograph attached to the Gran Telescopio CANARIAS (GTC, Roque de los Muchachos Observatory, La Palma, Spain) using the Si2-8.7, Si6-12.5, and Q1-17.65 filters with the aim of deriving Apophis' diameter (D), geometric albedo (p V ), and thermal inertia (Γ). Methods. We performed a detailed thermophysical model analysis of the GTC data combined with previously published thermal data obtained using Herschel Space Observatory PACS instrument at 70, 100, and 160 μm.Results. The thermophysical model fit of the data favors low surface roughness solutions (within a range of roughness slope angles rms between 0.1 and 0.5), and constrains the effective diameter, visible geometric albedo, and thermal inertia of Apophis to be D eff = 380-393 m, p V = 0.24-0.33 (assuming absolute magnitude H = 19.09 ± 0.19) and Γ = 50-500 Jm −2 −0.5 K −1 , respectively.

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“…Chesley (2006) and Giorgini et al (2008) pointed out the importance of past and future radar observations for reducing the uncertainties in Apophis' orbit and drift parameters. Bancelin et al (2012a) and Farnocchia et al (2013) also studied the impact of astrometric measurements in this respect. Their results indicate that high quality astrometric data can make a substantial contribution to improving NEA impact predictions by reducing orbit uncertainties even when radar observations are available.…”

Section: The Pha (99 942) Apophismentioning

confidence: 99%

The astrometricGaia-FUN-SSO observation campaign of 99942 Apophis

Thuillot

Bancelin

Ivantsov

et al. 2015

A&A

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Aims. Astrometric observations performed by the Gaia Follow-Up Network for Solar System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects first detected by ESA's Gaia mission remain recoverable after their discovery. An observation campaign on the potentially hazardous asteroid (99 942) Apophis was conducted during the asteroid's latest period of visibility, from 12/21/2012 to 5/2/2013, to test the coordination and evaluate the overall performance of the Gaia-FUN-SSO . Methods. The 2732 high quality astrometric observations acquired during the Gaia-FUN-SSO campaign were reduced with the Platform for Reduction of Astronomical Images Automatically (PRAIA), using the USNO CCD Astrograph Catalogue 4 (UCAC4) as a reference. The astrometric reduction process and the precision of the newly obtained measurements are discussed. We compare the residuals of astrometric observations that we obtained using this reduction process to data sets that were individually reduced by observers and accepted by the Minor Planet Center. Results. We obtained 2103 previously unpublished astrometric positions and provide these to the scientific community. Using these data we show that our reduction of this astrometric campaign with a reliable stellar catalog substantially improves the quality of the astrometric results. We present evidence that the new data will help to reduce the orbit uncertainty of Apophis during its close approach in 2029. We show that uncertainties due to geolocations of observing stations, as well as rounding of astrometric data can introduce an unnecessary degradation in the quality of the resulting astrometric positions. Finally, we discuss the impact of our campaign reduction on the recovery process of newly discovered asteroids.

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Yarkovsky-driven impact risk analysis for asteroid (99942) Apophis

Cited by 107 publications

References 29 publications

Differentiation signatures in the Flora region

Differentiation signatures in the Flora region

GTC/CanariCam observations of (99942) Apophis

The astrometricGaia-FUN-SSO observation campaign of 99942 Apophis

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