70 research outputs found
Unbiased Inclination Distributions for Objects in the Kuiper Belt
Using data from the Deep Ecliptic Survey (DES), we investigate the
inclination distributions of objects in the Kuiper Belt. We present a
derivation for observational bias removal and use this procedure to generate
unbiased inclination distributions for Kuiper Belt objects (KBOs) of different
DES dynamical classes, with respect to the Kuiper Belt Plane. Consistent with
previous results, we find that the inclination distribution for all DES KBOs is
well fit by the sum of two Gaussians, or a Gaussian plus a generalized
Lorentzian, multiplied by sin i. Approximately 80% of KBOs are in the
high-inclination grouping. We find that Classical object inclinations are well
fit by sin i multiplied by the sum of two Gaussians, with roughly even
distribution between Gaussians of widths 2.0 -0.5/+0.6 degrees and 8.1
-2.1/+2.6 degrees. Objects in different resonances exhibit different
inclination distributions. The inclinations of Scattered objects are best
matched by sin i multiplied by a single Gaussian that is centered at 19.1
-3.6/+3.9 degrees with a width of 6.9 -2.7/+4.1 degrees. Centaur inclinations
peak just below 20 degrees, with one exceptionally high-inclination object near
80 degrees. The currently observed inclination distribution of the Centaurs is
not dissimilar to that of the Scattered Extended KBOs and Jupiter-family
comets, but is significantly different from the Classical and Resonant KBOs.
While the sample sizes of some dynamical classes are still small, these results
should begin to serve as a critical diagnostic for models of Solar System
evolution.Comment: Accepted for publication in the Astronomical Journa
TRIPPy: Trailed Image Photometry in Python
Photometry of moving sources typically suffers from reduced signal-to-noise
(SNR) or flux measurements biased to incorrect low values through the use of
circular apertures. To address this issue we present the software package,
TRIPPy: TRailed Image Photometry in Python. TRIPPy introduces the pill
aperture, which is the natural extension of the circular aperture appropriate
for linearly trailed sources. The pill shape is a rectangle with two
semicircular end-caps, and is described by three parameters, the trail length
and angle, and the radius. The TRIPPy software package also includes a new
technique to generate accurate model point-spread functions (PSF) and trailed
point-spread functions (TSF) from stationary background sources in sidereally
tracked images. The TSF is merely the convolution of the model PSF, which
consists of a moffat profile, and super sampled lookup table. From the TSF,
accurate pill aperture corrections can be estimated as a function of pill
radius with a accuracy of 10 millimags for highly trailed sources. Analogous to
the use of small circular apertures and associated aperture corrections, small
radius pill apertures can be used to preserve signal-to-noise of low flux
sources, with appropriate aperture correction applied to provide an accurate,
unbiased flux measurement at all SNR.Comment: 8 Figures, 11 Pages, Accepted to the Astronomical Journa
Col-OSSOS: Colors of the Interstellar Planetesimal 1I/`Oumuamua
The recent discovery by Pan-STARRS1 of 1I/2017 U1 (`Oumuamua), on an unbound
and hyperbolic orbit, offers a rare opportunity to explore the planetary
formation processes of other stars, and the effect of the interstellar
environment on a planetesimal surface. 1I/`Oumuamua's close encounter with the
inner Solar System in 2017 October was a unique chance to make observations
matching those used to characterize the small-body populations of our own Solar
System. We present near-simultaneous g, r, and J photometry
and colors of 1I/`Oumuamua from the 8.1-m Frederick C. Gillett Gemini North
Telescope, and photometry from the 4.2 m William Herschel Telescope. Our
grJ observations are directly comparable to those from the
high-precision Colours of the Outer Solar System Origins Survey (Col-OSSOS),
which offer unique diagnostic information for distinguishing between outer
Solar System surfaces. The J-band data also provide the highest signal-to-noise
measurements made of 1I/`Oumuamua in the near-infrared. Substantial, correlated
near-infrared and optical variability is present, with the same trend in both
near-infrared and optical. Our observations are consistent with 1I/`Oumuamua
rotating with a double-peaked period of hours and being a
highly elongated body with an axial ratio of at least 5.3:1, implying that it
has significant internal cohesion. The color of the first interstellar
planetesimal is at the neutral end of the range of Solar System and
solar-reflectance colors: it is like that of some dynamically excited objects
in the Kuiper belt and the less-red Jupiter Trojans.Comment: Accepted to ApJ
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