| 1. |
- Abrahamsen, E. Povl, et al.
(författare)
-
ANTARCTICA AND THE SOUTHERN OCEAN
- 2020
-
Ingår i: BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY. - 0003-0007 .- 1520-0477. ; 101:8
-
Tidskriftsartikel (refereegranskat)
|
|
| 2. |
|
|
| 3. |
- Devogèle, Maxime, et al.
(författare)
-
New Evidence for a Physical Link between Asteroids (155140) 2005 UD and (3200) Phaethon
- 2020
-
Ingår i: The Planetary Science Journal. - : Institute of Physics (IOP). - 2632-3338. ; 1:1
-
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.
|
|
| 4. |
- MacLennan, Eric, et al.
(författare)
-
Dynamical evolution and thermal history of asteroids (3200) Phaethon and (155140) 2005 UD
- 2021
-
Ingår i: Icarus. - : Elsevier. - 0019-1035 .- 1090-2643. ; 366
-
Tidskriftsartikel (refereegranskat)abstract
- The near-Earth objects (NEOs) (3200) Phaethon and (155140) 2005 UD are thought to share a common origin, with the former exhibiting dust activity at perihelion that is thought to directly supply the Geminid meteor stream. Both of these objects currently have very small perihelion distances (0.140au and 0.163au for Phaethon and 2005 UD, respectively), which results in them having perihelion temperatures around 1000K. A comparison between NEO population models to discovery statistics suggests that low-perihelion objects are destroyed over time by a, possibly temperature-dependent, mechanism that is efficient at heliocentric distances less than 0.3au. By implication, the current activity from Phaethon is linked to the destruction mechanism of NEOs close to the Sun.We model the past thermal characteristics of Phaethon and 2005 UD using a combination of a thermophysical model (TPM) and orbital integrations of each object. Temperature characteristics such as maximum daily temperature, maximum thermal gradient, and temperature at different depths are extracted from the model, which is run for a predefined set of semi-major axis and eccentricity values. Next, dynamical integrations of orbital clones of Phaethon and 2005 UD are used to estimate the past orbital elements of each object. These dynamical results are then combined with the temperature characteristics to model the past evolution of thermal characteristics such as maximum (and minimum) surface temperature and thermal gradient. The orbital histories of Phaethon and 2005 UD are characterized by cyclic changes in e, resulting in perihelia values periodically shifting between present-day values and 0.3au. Currently, Phaethon is experiencing relatively large degrees of heating when compared to the recent 20,000yr. We find that the subsurface temperatures are too large over this timescale for water ice to be stable, unless actively supplied somehow. The near-surface thermal gradients strongly suggest that thermal fracturing may be very effective at breaking down and ejecting dust particles. Observations by the DESTINY+ flyby mission will provide important constraints on the mechanics of dust-loss from Phaethon and, potentially, reveal signs of activity from 2005 UD.In addition to simulating the recent dynamical evolution of these objects, we use orbital integrations that start from the Main Belt to assess their early dynamical evolution (origin and delivery mechanism). We find that dwarf planet (2) Pallas is unlikely to be the parent body for Phaethon and 2005 UD, and it is more likely that the source is in the inner part of the asteroid belt in the families of, e.g., (329) Svea or (142) Polana.
|
|
| 5. |
- MacLennan, Eric, et al.
(författare)
-
Evidence of surface heterogeneity on active asteroid (3200) Phaethon
- 2022
-
Ingår i: Icarus. - : Elsevier. - 0019-1035 .- 1090-2643. ; 388
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal infrared emission and thermophysical modeling techniques are powerful tools in deciphering the surface properties of asteroids. The near-Earth asteroid (3200) Phaethon is an active asteroid with a very small perihelion distance and is likely the source of the Geminid meteor shower. Using a thermophysical model with a non-convex shape of Phaethon we interpret thermal infrared observations that span ten distinct sightings. The results yield an effective diameter of 5.4 ± 0.1 km and independent thermal inertia estimates for each sighting. We find that the thermal inertia varies across each of these sightings in a way that is stronger than the theoretical temperature-dependent expectation from radiative heat transfer within the regolith. Thus, we test whether the variation in thermal inertia can be explained by the presence of a regolith layer over bedrock, or by a spatially heterogeneous scenario. We find that a model in which Phaethon's hemispheres have distinctly different thermophysical properties can sufficiently explain the thermal inertias determined herein. In particular, we find that a boundary is located between latitudes -ˆ’30°ˆ˜ and +10° and a northern hemisphere that is dominated by coarse-grained regolith and/or a high coverage of porous boulders. We discuss the implications related to Phaethon'€™s activity, potential association with 2005 UD, and the upcoming DESTINY+ mission.
|
|
| 6. |
|
|
