1,827 research outputs found
Pencil-Beam Surveys for Trans-Neptunian Objects: Novel Methods for Optimization and Characterization
Digital co-addition of astronomical images is a common technique for
increasing signal-to-noise and image depth. A modification of this simple
technique has been applied to the detection of minor bodies in the Solar
System: first stationary objects are removed through the subtraction of a
high-SN template image, then the sky motion of the Solar System bodies of
interest is predicted and compensated for by shifting pixels in software prior
to the co-addition step. This "shift-and-stack" approach has been applied with
great success in directed surveys for minor Solar System bodies. In these
surveys, the shifts have been parameterized in a variety of ways. However,
these parameterizations have not been optimized and in most cases cannot be
effectively applied to data sets with long observation arcs due to objects'
real trajectories diverging from linear tracks on the sky. This paper presents
two novel probabilistic approaches for determining a near-optimum set of
shift-vectors to apply to any image set given a desired region of orbital space
to search. The first method is designed for short observational arcs, and the
second for observational arcs long enough to require non-linear shift-vectors.
Using these techniques and other optimizations, we derive optimized grids for
previous surveys that have used "shift-and-stack" approaches to illustrate the
improvements that can be made with our method, and at the same time derive new
limits on the range of orbital parameters these surveys searched. We conclude
with a simulation of a future applications for this approach with LSST, and
show that combining multiple nights of data from such next-generation
facilities is within the realm of computational feasibility.Comment: Accepted for publication in PASP March 1, 2010
Trans-Neptunian Space and the Post-Pluto Paradigm
The Pluto system is an archetype for the multitude of icy dwarf planets and
accompanying satellite systems that populate the vast volume of the solar
system beyond Neptune. New Horizons' exploration of Pluto and its five moons
gave us a glimpse into the range of properties that their kin may host.
Furthermore, the surfaces of Pluto and Charon record eons of bombardment by
small trans-Neptunian objects, and by treating them as witness plates we can
infer a few key properties of the trans-Neptunian population at sizes far below
current direct-detection limits. This chapter summarizes what we have learned
from the Pluto system about the origins and properties of the trans-Neptunian
populations, the processes that have acted upon those members over the age of
the solar system, and the processes likely to remain active today. Included in
this summary is an inference of the properties of the size distribution of
small trans-Neptunian objects and estimates on the fraction of binary systems
present at small sizes. Further, this chapter compares the extant properties of
the satellites of trans-Neptunian dwarf planets and their implications for the
processes of satellite formation and the early evolution of planetesimals in
the outer solar system. Finally, this chapter concludes with a discussion of
near-term theoretical, observational, and laboratory efforts that can further
ground our understanding of the Pluto system and how its properties can guide
future exploration of trans-Neptunian space.Comment: Review chapter in "The Pluto System After New Horizons" University of
Arizona Press, 2021.
https://uapress.arizona.edu/book/the-pluto-system-after-new-horizon
Pencil-Beam Surveys for Trans-Neptunian Objects: Limits on Distant Populations
Two populations of minor bodies in the outer Solar System remain particularly
elusive: Scattered Disk objects and Sedna-like objects. These populations are
important dynamical tracers, and understanding the details of their spatial-
and size-distributions will enhance our understanding of the formation and
on-going evolution of the Solar System. By using newly-derived limits on the
maximum heliocentric distances that recent pencil-beam surveys for
Trans-Neptunian Objects were sensitive to, we determine new upper limits on the
total numbers of distant SDOs and Sedna-like objects. While generally
consistent with populations estimated from wide-area surveys, we show that for
magnitude-distribution slopes of {\alpha} > 0.7-1.0, these pencil-beam surveys
provide stronger upper limits than current estimates in literature.Comment: Submitted to Icaru
New Horizons: Long-Range Kuiper Belt Targets Observed by the Hubble Space Telescope
We report on Hubble Space Telescope (HST) observations of three Kuiper Belt
Objects (KBOs), discovered in our dedicated ground-based search campaign, that
are candidates for long-range observations from the New Horizons spacecraft:
2011 JY31, 2011 HZ102, and 2013 LU35. Astrometry with HST enables both current
and future critical accuracy improvements for orbit precision, required for
possible New Horizons observations, beyond what can be obtained from the
ground. Photometric colors of all three objects are red, typical of the Cold
Classical dynamical population within which they reside; they are also the
faintest KBOs to have had their colors measured. None are observed to be binary
with HST above separations of ~0.02 arcsec (~700 km at 44 AU) and {\Delta}m
less than or equal to 0.5.Comment: Pages: 11, Figures: 2, Tables: 3, Icarus, available online May 2014
(http://dx.doi.org/10.1016/j.icarus.2014.04.014
Extinction in Lotka-Volterra model
Competitive birth-death processes often exhibit an oscillatory behavior. We
investigate a particular case where the oscillation cycles are marginally
stable on the mean-field level. An iconic example of such a system is the
Lotka-Volterra model of predator-prey competition. Fluctuation effects due to
discreteness of the populations destroy the mean-field stability and eventually
drive the system toward extinction of one or both species. We show that the
corresponding extinction time scales as a certain power-law of the population
sizes. This behavior should be contrasted with the extinction of models stable
in the mean-field approximation. In the latter case the extinction time scales
exponentially with size.Comment: 11 pages, 17 figure
OSSOS: XXVII. Population Estimates for Theoretically Stable Centaurs Between Uranus and Neptune
We calculate the upper bounds of the population of theoretically stable
Centaur orbits between Uranus and Neptune. These small bodies are on
low-eccentricity, low-inclination orbits in two specific bands of semi-major
axis, centred at 24.6 au and 25.6 au. They exhibit unusually long
Gyr-stable lifetimes in previously published numerical integrations, orders of
magnitude longer than that of a typical Centaur. Despite the increased breadth
and depth of recent solar system surveys, no such objects have been found.
Using the Outer Solar System Origins Survey (OSSOS) survey simulator to
calculate the detection efficiency for these objects in an ensemble of fully
characterised surveys, we determine that a population of 72 stable Centaurs
with absolute magnitude ( confidence upper limit) could
remain undetected. The upcoming Legacy Survey of Space and Time (LSST) will be
able to detect this entire intrinsic population due to its complete coverage of
the ecliptic plane. If detected, these objects will be interesting
dynamically-accessible mission targets -- especially as comparison of the
stable Centaur orbital phase space to the outcomes of several modern planetary
migration simulations suggests that these objects could be close to primordial
in nature.Comment: Accepted to PSJ. 8 pages, 3 figures. Comments welcom
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