| 1. |
- Devogèle, Maxime, et al.
(författare)
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New Evidence for a Physical Link between Asteroids (155140) 2005 UD and (3200) Phaethon
- 2020
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Ingår i: The Planetary Science Journal. - : Institute of Physics (IOP). - 2632-3338. ; 1:1
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Tidskriftsartikel (refereegranskat)abstract
- In 2018, the near-Earth object (155140) 2005 UD (hereafter UD) experienced a close fly by of the Earth. We present results from an observational campaign involving photometric, spectroscopic, and polarimetric observations carried out across a wide range of phase angles (07–88°). We also analyze archival NEOWISE observations. We report an absolute magnitude of H V = 17.51 ± 0.02 mag and an albedo of p V = 0.10 ± 0.02. UD has been dynamically linked to Phaethon due their similar orbital configurations. Assuming similar surface properties, we derived new estimates for the diameters of Phaethon and UD of D = 5.4 ± 0.5 km and D = 1.3 ± 0.1 km, respectively. Thermophysical modeling of NEOWISE data suggests a surface thermal inertia of and regolith grain size in the range of 0.9–10 mm for UD and grain sizes of 3–30 mm for Phaethon. The light curve of UD displays a symmetric shape with a reduced amplitude of Am(0) = 0.29 mag and increasing at a linear rate of 0.017 mag/° between phase angles of 0° and ~25°. Little variation in light-curve morphology was observed throughout the apparition. Using light-curve inversion techniques, we obtained a sidereal rotation period P = 5.235 ± 0.005 hr. A search for rotational variation in spectroscopic and polarimetric properties yielded negative results within observational uncertainties of ~10% μm−1 and ~16%, respectively. In this work, we present new evidence that Phaethon and UD are similar in composition and surface properties, strengthening the arguments for a genetic relationship between these two objects.
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| 2. |
- Geem, Jooyeon, et al.
(författare)
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(3200) Phaethon polarimetry in the negative branch: new evidence for the anhydrous nature of the DESTINY+ target asteroid
- 2022
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Ingår i: Monthly Notices of the Royal Astronomical Society: Letters. - : Oxford University Press. - 1745-3925 .- 1745-3933. ; 516:1, s. L53-L57
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first polarimetric study of (3200) Phaethon, the target of JAXA’s DESTINY+ mission, in the negative branch to ensure its anhydrous nature and to derive an accurate geometric albedo. We conducted observations at low phase angles (Sun-target-observer angle, α = 8.8–32.4°) from 2021 October to 2022 January and found that Phaethon has a minimum polarization degree Pmin = −1.3 ± 0.1 per cent, a polarimetric slope h = 0.22 ± 0.02 per cent deg−1, and an inversion angle α0 = 19.9 ± 0.3°. The derived geometric albedo is pV = 0.11 (in the range of 0.08–0.13). These polarimetric properties are consistent with anhydrous chondrites, contradict hydrous chondrites, and typical cometary nuclei.
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| 3. |
- Ishiguro, Masateru, et al.
(författare)
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Polarimetric properties of the near-Sun asteroid (155140) 2005 UD in comparison with other asteroids and meteoritic samples
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 509:3, s. 4128-4142
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Tidskriftsartikel (refereegranskat)abstract
- The investigation of asteroids near the Sun is important for understanding the final evolutionary stage of primitive Solar system objects. A near-Sun asteroid (NSA), (155140) 2005 UD, has orbital elements similar to those of (3200) Phaethon (the target asteroid for the JAXA’s DESTINY+ mission). We conducted photometric and polarimetric observations of 2005 UD and found that this asteroid exhibits a polarization phase curve similar to that of Phaethon over a wide range of observed solar phase angles (α = 20–105°) but different from those of (101955) Bennu and (162173) Ryugu (asteroids composed of hydrated carbonaceous materials). At a low phase angle (α ≲ 30°), the polarimetric properties of these NSAs (2005 UD and Phaethon) are consistent with anhydrous carbonaceous chondrites, while the properties of Bennu are consistent with hydrous carbonaceous chondrites. We derived the geometric albedo, pV ∼ 0.1 (in the range of 0.088–0.109); mean V-band absolute magnitude, HV = 17.54 ± 0.02; synodic rotational period, Trot=5.2388±0.0022h (the two-peaked solution is assumed); and effective mean diameter, Deff=1.32±0.06km. At large phase angles (α ≳ 80°), the polarization phase curve are likely explained by the dominance of large grains and the paucity of small micron-sized grains. We conclude that the polarimetric similarity of these NSAs can be attributed to the intense solar heating of carbonaceous materials around their perihelia, where large anhydrous particles with small porosity could be produced by sintering.
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| 4. |
- Kueny, Jay K., et al.
(författare)
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Implications for the Formation of (155140) 2005 UD from a New Convex Shape Model
- 2023
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Ingår i: The Planetary Science Journal. - : Institute of Physics (IOP). - 2632-3338. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- (155140) 2005 UD has a similar orbit to (3200) Phaethon, an active asteroid in a highly eccentric orbit thought to be the source of the Geminid meteor shower. Evidence points to a genetic relationship between these two objects, but we have yet to fully understand how 2005 UD and Phaethon could have separated into this associated pair. Presented herein are new observations of 2005 UD from five observatories that were carried out during the 2018, 2019, and 2021 apparitions. We implemented light curve inversion using our new data, as well as dense and sparse archival data from epochs in 2005–2021, to better constrain the rotational period and derive a convex shape model of 2005 UD. We discuss two equally well-fitting pole solutions (λ = 116 6, β = −53 6) and (λ = 300 3, β = −55 4), the former largely in agreement with previous thermophysical analyses and the latter interesting due to its proximity to Phaethon's pole orientation. We also present a refined sidereal period of Psid = 5.234246 ± 0.000097 hr. A search for surface color heterogeneity showed no significant rotational variation. An activity search using the deepest stacked image available of 2005 UD near aphelion did not reveal a coma or tail but allowed modeling of an upper limit of 0.04–0.37 kg s−1 for dust production. We then leveraged our spin solutions to help limit the range of formation scenarios and the link to Phaethon in the context of nongravitational forces and timescales associated with the physical evolution of the system.
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| 5. |
- Siltala, Lauri, et al.
(författare)
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Mass and Density of Asteroid (16) Psyche
- 2021
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8205 .- 2041-8213. ; 909:1
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Tidskriftsartikel (refereegranskat)abstract
- We apply our novel Markov Chain Monte Carlo (MCMC)–based algorithm for asteroid mass estimation to asteroid (16) Psyche, the target of NASA's eponymous Psyche mission, based on close encounters with 10 different asteroids, and obtain a mass of (1.117 ± 0.039) × 10−11 M⊙. We ensure that our method works as expected by applying it to asteroids (1) Ceres and (4) Vesta, and find that the results are in agreement with the very accurate mass estimates for these bodies obtained by the Dawn mission. We then combine our mass estimate for Psyche with the most recent volume estimate to compute the corresponding bulk density as (3.88 ± 0.25) g cm−3. The estimated bulk density rules out the possibility of Psyche being an exposed, solid iron core of a protoplanet, but is fully consistent with the recent hypothesis that ferrovolcanism would have occurred on Psyche.
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