44 research outputs found
On the genesis of the Haumea system
The scenarios proposed in the literature for the genesis of the system formed by the dwarf planet 136108 Haumea, its two satellites and a group of some 10 bodies (the family) with semimajor axes, eccentricities and inclinations close to Haumea's values, are analysed against collisional, physical, dynamical and statistical arguments in order to assess their likelihood. All scenarios based on collisional events are reviewed under physical arguments and the corresponding formation probabilities in a collisional environment are evaluated according to the collisional evolution model alicandep. An alternative mechanism is proposed based on the potential possibility of (quasi-) independent origin of the family with respect to Haumea and its satellites. As a general conclusion the formation of the Haumea system is a low-probability event in the currently assumed frame for the evolution of the outer Solar system. However, it is possible that current knowledge is missing some key element in the whole story that may contribute to increase the odds for the formation of such a system.Facultad de Ciencias Astronómicas y Geofísica
The CFEPS Kuiper Belt Survey: Strategy and Pre-survey Results
We present the data acquisition strategy and characterization procedures for
the Canada-France Ecliptic Plane Survey (CFEPS), a sub-component of the
Canada-France-Hawaii Telescope Legacy Survey. The survey began in early 2003
and as of summer 2005 has covered 430 square degrees of sky within a few
degrees of the ecliptic. Moving objects beyond the orbit of Uranus are detected
to a magnitude limit of =23 -- 24 (depending on the image quality). To
track as large a sample as possible and avoid introducing followup bias, we
have developed a multi-epoch observing strategy that is spread over several
years. We present the evolution of the uncertainties in ephemeris position and
orbital elements as the objects progress through the epochs. We then present a
small 10-object sample that was tracked in this manner as part of a preliminary
survey starting a year before the main CFEPS project.
We describe the CFEPS survey simulator, to be released in 2006, which allows
theoretical models of the Kuiper Belt to be compared with the survey
discoveries since CFEPS has a well-documented pointing history with
characterized detection efficiencies as a function of magnitude and rate of
motion on the sky. Using the pre-survey objects we illustrate the usage of the
simulator in modeling the classical Kuiper Belt.Comment: to be submitted to Icaru
Rotational fission of Trans-Neptunian Objects. The case of Haumea
We present several lines of evidence based on different kinds of observations
to conclude that rotational fission has likely occurred for a fraction of the
known Trans-Neptunian Objects (TNOs). It is also likely that a number of binary
systems have formed from that process in the trans-neptunian belt. We show that
Haumea is a potential example of an object that has suffered a rotational
fission. Its current fast spin would be a slight evolution of a primordial fast
spin, rather than the result of a catastrophic collision, because the
percentage of objects rotating faster than 4 hours would not be small in a
maxwellian distribution of spin rates that fits the current TNO rotation
database. On the other hand, the specific total angular momentum of Haumea and
its satellites falls close to that of the high size ratio asteroid binaries,
which are thought to be the result of rotational fissions or mass shedding. We
also present N-body simulations of rotational fissions applied to the case of
Haumea, which show that this process is feasible, might have generated
satellites, and might have even created a "family" of bodies orbitally
associated to Haumea. The orbitally associated bodies may come from the direct
ejection of fragments according to our simulations, or through the evolution of
a proto-satellite formed during the fission event. Also, the disruption of an
escaped fragment after the fission might create the orbitally related bodies.
If any of those mechanisms are correct, other rotational fission families may
be detectable in the trans-neptunian belt in the future, and perhaps even TNO
pairs might be found (pairs of bodies sharing very similar orbital elements,
but not bound together)
The Canada-France Ecliptic Plane Survey - Full Data Release: The orbital structure of the Kuiper belt
We report the orbital distribution of the trans-neptunian objects (TNOs)
discovered during the Canada-France Ecliptic Plane Survey, whose discovery
phase ran from early 2003 until early 2007. The follow-up observations started
just after the first discoveries and extended until late 2009. We obtained
characterized observations of 321 sq.deg. of sky to depths in the range g ~
23.5--24.4 AB mag. We provide a database of 169 TNOs with high-precision
dynamical classification and known discovery efficiency. Using this database,
we find that the classical belt is a complex region with sub-structures that go
beyond the usual splitting of inner (interior to 3:2 mean-motion resonance
[MMR]), outer (exterior to 2:1 MMR), and main (in between). The main classical
belt (a=40--47 AU) needs to be modeled with at least three components: the
`hot' component with a wide inclination distribution and two `cold' components
(stirred and kernel) with much narrower inclination distributions. The hot
component must have a significantly shallower absolute magnitude (Hg)
distribution than the other two components. With 95% confidence, there are
8000+1800-1600 objects in the main belt with Hg <= 8.0, of which 50% are from
the hot component, 40% from the stirred component and 10% from the kernel; the
hot component's fraction drops rapidly with increasing Hg. Because of this, the
apparent population fractions depend on the depth and ecliptic latitude of a
trans-neptunian survey. The stirred and kernel components are limited to only a
portion of the main belt, while we find that the hot component is consistent
with a smooth extension throughout the inner, main and outer regions of the
classical belt; the inner and outer belts are consistent with containing only
hot-component objects. The Hg <= 8.0 TNO population estimates are 400 for the
inner belt and 10,000 for the outer belt within a factor of two.Comment: 59 pages, 9 figures, 7 table
Phase curves of small bodies from the SLOAN Moving Objects Catalog
Context. Extensive photometric surveys continue to produce enormous stores of data on small bodies. These data are typically sparsely obtained at arbitrary (or unknown) rotational phases. Therefore, new methods for processing such data need to be developed to make the most of these vast catalogs.
Aims. We aim to produce a method of recreating the phase curves of small bodies by considering the uncertainties introduced by the nominal errors in the magnitudes and the effect introduced by rotational variations. We use the SLOAN Moving Objects Catalog data as a benchmark to construct phase curves of all small bodies in u′, g′, r′, i′, and z′ filters. From the phase curves, we obtain the absolute magnitudes and we use them to set up the absolute colors, which are the colors of the asteroids that are not affected by changes in the phase angle.
Methods. We selected objects with ≥3 observations taken in at least one filter and spanning over a minimum of 5 degrees in the phase angle. We developed a method that combines Monte Carlo simulations and Bayesian inference to estimate the absolute magnitudes using the HG photometric system.
Results. We obtained almost 15 000 phase curves, with about 12 000 of these including all five filters. The absolute magnitudes and absolute colors are compatible with previously published data that support our method.
Conclusions. The method we developed is fully automatic and well suited for a run based on large amounts of data. Moreover, it includes the nominal uncertainties in the magnitudes and the whole distribution of possible rotational states of the objects producing what are possibly less precise values, that is, larger uncertainties, but more accurate, namely, closer to the actual value. To our knowledge, this work is the first to include the effect of rotational variations in such a manner