52 research outputs found
Dynamical evolution of escaped plutinos, another source of Centaurs
It was shown in previous works the existence of weakly chaotic orbits in the
plutino population that diffuse very slowly. These orbits correspond to
long-term plutino escapers and then represent the plutinos that are escaping
from the resonance at present. In this paper we perform numerical simulations
in order to explore the dynamical evolution of plutinos recently escaped from
the resonance. The numerical simulations were divided in two parts. In the
first one we evolved 20,000 test particles in the resonance in order to detect
and select the long-term escapers. In the second one, we numerically integrate
the selected escaped plutinos in order to study their dynamical post escaped
behavior. Our main results include the characterization of the routes of escape
of plutinos and their evolution in the Centaur zone. We obtained a present rate
of escape of plutinos between 1 and 10 every 10 years. The escaped plutinos
have a mean lifetime in the Centaur zone of 108 Myr and their contribution to
the Centaur population would be a fraction of less than 6 % of the total
Centaur population. In this way, escaped plutinos would be a secondary source
of Centaurs.Comment: Accepted for publication in A&
Impactor flux and cratering on Ceres and Vesta: Implications for the early Solar System
We study the impactor flux and cratering on Ceres and Vesta caused by the
collisional and dynamical evolution of the asteroid Main Belt. We develop a
statistical code based on a well-tested model for the simultaneous evolution of
the Main Belt and NEA size distributions. This code includes catastrophic
collisions and noncollisional removal processes such as the Yarkovsky effect
and the orbital resonances. The model assumes that the dynamical depletion of
the early Main Belt was very strong, and owing to that, most Main Belt
comminution occurred when its dynamical structure was similar to the present
one. Our results indicate that the number of D > 1 km Main Belt asteroids
striking Ceres and Vesta over the Solar System history are approximately 4 600
and 1 100 respectively. The largest Main Belt asteroids expected to have
impacted Ceres and Vesta had diameters of 71.7 km and 21.1 km. The number of D
> 0.1 km craters on Ceres is \sim 3.4 \times 10^8 and 6.2 \times 10^7 on Vesta.
The number of craters with D > 100 km are 47 on Ceres and 8 on Vesta. Our study
indicates that the D = 460 km crater observed on Vesta had to be formed by the
impact of a D \sim 66.2 km projectile, which has a probability of occurr \sim
30% over the Solar System history. If significant discrepancies between our
results about the cratering on Ceres and Vesta and data obtained from the Dawn
Mission were found, they should be linked to a higher degree of collisional
evolution during the early Main Belt and/or the existence of the late heavy
bombardment. An increase in the collisional activity in the early phase may be
provided for an initial configuration of the giant planets consistent with, for
example, the Nice model. From this, the Dawn Mission would be able to give us
clues about the initial configuration of the early Solar System and its
subsequent dynamical evolution.Comment: Accepted for publication in Astronomy and Astrophysic
The Size Distributions of Asteroid Families in the SDSS Moving Object Catalog 4
Asteroid families, traditionally defined as clusters of objects in orbital
parameter space, often have distinctive optical colors. We show that the
separation of family members from background interlopers can be improved with
the aid of SDSS colors as a qualifier for family membership. Based on an
~88,000 object subset of the Sloan Digital Sky Survey Moving Object Catalog 4
with available proper orbital elements, we define 37 statistically robust
asteroid families with at least 100 members using a simple Gaussian
distribution model in both orbital and color space. The interloper rejection
rate based on colors is typically ~10% for a given orbital family definition,
with four families that can be reliably isolated only with the aid of colors.
About 50% of all objects in this data set belong to families, and this fraction
varies from about 35% for objects brighter than an H magnitude of 13 and rises
to 60% for objects fainter than this. The fraction of C-type objects in
families decreases with increasing H magnitude for H > 13, while the fraction
of S-type objects above this limit remains effectively constant. This suggests
that S-type objects require a shorter timescale for equilibrating the
background and family size distributions via collisional processing. The size
distributions for 15 families display a well-defined change of slope and can be
modeled as a "broken" double power-law. Such "broken" size distributions are
twice as likely for S-type familes than for C-type families, and are dominated
by dynamically old families. The remaining families with size distributions
that can be modeled as a single power law are dominated by young families. When
size distribution requires a double power-law model, the two slopes are
correlated and are steeper for S-type families.Comment: 50 pages, 16 figures, accepted for publication in Icaru
TNOs are Cool: A survey of the trans-Neptunian region V. Physical characterization of 18 Plutinos using Herschel PACS observations
We present Herschel PACS photometry of 18 Plutinos and determine sizes and
albedos for these objects using thermal modeling. We analyze our results for
correlations, draw conclusions on the Plutino size distribution, and compare to
earlier results. Flux densities are derived from PACS mini scan-maps using
specialized data reduction and photometry methods. In order to improve the
quality of our results, we combine our PACS data with existing Spitzer MIPS
data where possible, and refine existing absolute magnitudes for the targets.
The physical characterization of our sample is done using a thermal model.
Uncertainties of the physical parameters are derived using customized Monte
Carlo methods. The correlation analysis is performed using a bootstrap Spearman
rank analysis. We find the sizes of our Plutinos to range from 150 to 730 km
and geometric albedos to vary between 0.04 and 0.28. The average albedo of the
sample is 0.08 \pm 0.03, which is comparable to the mean albedo of Centaurs,
Jupiter Family comets and other Trans-Neptunian Objects. We were able to
calibrate the Plutino size scale for the first time and find the cumulative
Plutino size distribution to be best fit using a cumulative power law with q =
2 at sizes ranging from 120-400 km and q = 3 at larger sizes. We revise the
bulk density of 1999 TC36 and find a density of 0.64 (+0.15/-0.11) g cm-3. On
the basis of a modified Spearman rank analysis technique our Plutino sample
appears to be biased with respect to object size but unbiased with respect to
albedo. Furthermore, we find biases based on geometrical aspects and color in
our sample. There is qualitative evidence that icy Plutinos have higher albedos
than the average of the sample.Comment: 18 pages, 8 figures, 8 tables, accepted for publication in A&
GJ 273: On the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec
Context. Planets orbiting low-mass stars such as M dwarfs are now considered a cornerstone in the search for life-harbouring planets.
GJ 273 is a planetary system orbiting an M dwarf only 3.75 pc away, composed of two confirmed planets, GJ 273b and GJ 273c, and
two promising candidates, GJ 273d and GJ 273e. Planet GJ 273b resides in the habitable zone. Currently, due to a lack of observed
planetary transits, only the minimum masses of the planets are known: Mb sin ib=2.89 M⊕, Mc sin ic=1.18 M⊕, Md sin id=10.80 M⊕,
and Me sin ie=9.30 M⊕. Despite being an interesting system, the GJ 273 planetary system is still poorly studied.
Aims. We aim at precisely determine the physical parameters of the individual planets, in particular to break the mass–inclination
degeneracy to accurately determine the mass of the planets. Moreover, we present thorough characterisation of planet GJ 273b in
terms of its potential habitability.
Methods. First, we explored the planetary formation and hydration phases of GJ 273 during the first 100 Myr. Secondly, we analysed
the stability of the system by considering both the two- and four-planet configurations. We then performed a comparative analysis
between GJ 273 and the Solar System, and searched for regions in GJ 273 which may harbour minor bodies in stable orbits, i.e. main
asteroid belt and Kuiper belt analogues.
Results. From our set of dynamical studies, we obtain that the four-planet configuration of the system allows us to break the mass–
inclination degeneracy. From our modelling results, the masses of the planets are unveiled as: 2:89 ≤ Mb ≤ 3:03 M⊕, 1:18 ≤ Mc ≤
1:24 M⊕, 10:80 ≤ Md ≤ 11:35 M⊕ and 9:30 ≤ Me ≤ 9:70 M⊕. These results point to a system likely composed of an Earth-mass
planet, a super-Earth and two mini-Neptunes. From planetary formation models, we determine that GJ 273b was likely an efficient
water captor while GJ 273c is probably a dry planet. We found that the system may have several stable regions where minor bodies
might reside. Collectively, these results are used to comprehensively discuss the habitability of GJ 273bSpanish Ministry of Science and Education RamĂłn y Cajal programme
ESP2017-87676-2-2
RYC-2012-09913CONICYT- FONDECYT/Chile Postdoctorado 3180405MIT’s Kavli Institut
Impactor flux and cratering on the Pluto-Charon system
We study the impactor flux and cratering on Pluto and Charon due to the
collisional evolution of Plutinos. Plutinos are those trans-Neptunian objects
located at 39.5 AU, in the 3:2 mean motion resonance with Neptune. To do this,
we develop a statistical code that includes catastrophic collisions and
cratering events, and takes into account the stability and instability zones of
the 3:2 mean motion resonance with Neptune. We proposes different initial
populations that account for the uncertainty in the size distribution of
Plutinos at small sizes. Depending on the initial population, our results
indicate the following. The number of D > 1 km Plutinos streaking Pluto over
3.5 Gyr is between 1271 and 5552. For Charon, the number of D > 1 km Plutino
impactors is between 354 and 1545. The number of D > 1 km craters on Pluto
produced by Plutinos during the last 3.5 Gyr is between 43076 and 113879. For
Charon, the number of D > 1 km craters is between 20351 and 50688.The largest
Plutino impactor onto Pluto has a diameter between 17 and 23 km, which produces
a craterwith a diameter of 31 - 39 km. The largest Plutino impactor onto Charon
has a diameter between 10 and 15 km, which produces a crater with a diameter of
24 - 33 km. We test if 2 Pluto-sized objects are assumed in the 3:2 Neptune
resonance, then the total number of Plutino impactors both onto Pluto as Charon
with diameters D > 1 km is a factor of 1.6 - 1.8 larger if considering 1
Pluto-sized object. Given the dynamical structure of the trans-Neptunian
region, it is necessary to study in detail the contribution of all the
potential sources of impactors on the Pluto-Charon system, to obtain the main
contributor and the whole production of craters. Then, we will be able to
contrast those studies with observations which will help us to understand the
geological processes and history of the surface of those worlds.Comment: Accepted for publication in A&
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