The tumbling spin state of (99942) Apophis

Pravec, Petr; Scheirich, P.; Ďurech, Josef; Pollock, J.; Kušnirák, P.; Hornoch, K.; Galád, A.; Vokrouhlický, David; Harris, Alan W.; Jehin, Emmanuël; Manfroid, Jean; Opitom, Cyrielle; Gillon, M.; Colas, François; Oey, Julian; Vraštil, J.; Reichart, D. E.; Ivarsen, K.; Haislip, J.; Lacluyzé, A.

doi:10.1016/j.icarus.2014.01.026

Cited by 115 publications

(206 citation statements)

References 34 publications

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“…We assumed a constant emissivity of 0.9 at all wavelengths. We also used the mean absolute magnitude H V = 19.09 ± 0.19 mag derived by Pravec et al (2014) under the assumption of a slope parameter of G = 0.24 ± 0.11. The observational circumstances of Herschel Space Observatory data are summarized in Table 1 of Müller et al (2014); GTC observations were obtained with the asteroid at heliocentric and geocentric distances r helio = 1.080 AU and Δ obs = 0.113, respectively, and a phase angle α = −31.7 degrees.…”

Section: Thermophysical Modelingmentioning

confidence: 99%

“…They obtained data at 70, 100, and 160 μm at two epochs and performed a detailed thermophysical model (TPM) analysis. They used the spin and shape model and absolute magnitude H = 19.09 ± 0.19 by Pravec et al (2014) Delbo et al (2007) from their p V determination is the result of a different value of H (H = 19.09 and H = 19.7, respectively). The Vokrouhlický et al (2015) results use the Pravec et al (2014) and Müller et al (2014) results to evaluate the Yarkovsky effect on the orbital evolution of Apophis; in particular, they use the range of Γ values provided by Müller et al (2014).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Thermophysical Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

GTC/CanariCam observations of (99942) Apophis

Licandro

Müller

Álvarez

et al. 2015

A&A

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“…The period analysis reveals a long double period with P 1 = 82.188 h and P 2 = 67.13 h. With these periods, we reconstruct the full-coverage light curve of (5247) Krylov and confirm that it is a NPA rotator in the MB. According to Pravec et al (2014), the plausible Gravitational pull during a planetary flyby. Based on the above-mentioned possibilities, we can speculate on the formation scenario of (524) Kryolv.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…(Code 3: "unclear".) (Pravec et al 2014), both of which are Near Earth Asteroids (NEAs). Until recently, studies on NPA rotators have been focused only on NEAs and no investigations have been conducted for MBAs (Main Belt Asteroids).…”

Section: Introductionmentioning

confidence: 99%

Photometric Study of Npa Rotator (5247) Krylov

Lee¹,

Moon²,

Kim³

et al. 2017

Journal of The Korean Astronomical Society

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Abstract:We conduct BVRI and R band photometric observations of asteroid (5247) Krylov from January 2016 to April 2016 for 51 nights using the Korea Microlensing Telescope Network (KMTNet). The color indices of (5247) Krylov at the light curve maxima are determined as B − V = 0.841 ± 0.035, V − R = 0.418 ± 0.031, and V − I = 0.871 ± 0.031 where the phase angle is 14.1• . They are acquired after the standardization of BVRI instrumental measurements using the ensemble normalization technique. Based on the color indices, (5247) Krylov is classified as a S-type asteroid. Double periods, that is, a primary period P 1 = 82.188 ± 0.013 h and a secondary period P 2 = 67.13 ± 0.20 h are identified from period searches of its R band light curve. The light curve phases with P 1 and this indicate that it is a typical Non-Principal Axis (NPA) asteroid. We discuss the possible causes of its NPA rotation.

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“…This is because the available data can be fit with a model in which the body rotates about the shortest principal axis of the inertia tensor with a single sidereal rotation frequency. Consider, however, that the standard theory of the rotation wobble damping (e.g., Harris 1994;Sharma et al 2005;Breiter et al 2012;Pravec et al 2014) would predict a characteristic de-excitation timescale of 6 Gyr (assuming µ Q 10 11 , SI units, where µ is rigidity and Q quality factor). This is four orders of magnitude longer than the age of the Datura family.…”

Section: Rotation Pole and Shape Model For (89309) 2001 Vn36mentioning

confidence: 99%

The young Datura asteroid family

Vokrouhlický

Pravec

Ďurech

et al. 2017

A&A

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Context. Asteroid families are the outcomes of disruption or cratering events on a size and energy scales that are not reproducible in laboratory experiments. Overall structure, as well as properties of individual members, in the old families could have been changed since their formation. Therefore young families preserve best the characteristics of the initial event. Aims. We study the most suitable known asteroid family with an age of less than 1 Myr, the Datura family. We aim (i) to obtain information about rotation state and shape of the largest members in the family; and (ii) to constrain its debiased population down to couple of hundreds of meters in size. Methods. We have analyzed the up-to-date catalog of orbital elements of main belt asteroids. We evaluated the detection efficiency of Catalina Sky Survey (CSS) in regard to detections of members in the Datura family, and we have used our photometric observations and lightcurve inversion methods to determine the rotation states and shapes of the largest members of the family. Results. We determined rotation periods of the seven largest members of the Datura family, and we also derived accurate mean absolute magnitudes for six of them. Except for the largest fragment (1270) Datura, the asteroids tend to have long rotation periods and large amplitude of the lightcurve, witnessing an elongated shape. For the four largest asteroids, our observations allow us to resolve rotation pole and a rough shape. All of them are prograde-rotating and have the latitude of the rotation pole >50 • . Our search in orbital catalogs resulted in the discovery of many small, sub-kilometer members of the Datura family. Using the CSS detection efficiency, we inverted this information into the debiased population of Datura family members. We show that the mass and angular momentum content in small fragments is negligible compared to the largest fragment (1270) Datura. These findings may help to constrain the formation mechanism of the family.

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The tumbling spin state of (99942) Apophis

Cited by 115 publications

References 34 publications

GTC/CanariCam observations of (99942) Apophis

GTC/CanariCam observations of (99942) Apophis

Photometric Study of Npa Rotator (5247) Krylov

The young Datura asteroid family

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