513 research outputs found
The Color Differences of Kuiper Belt Objects in Resonance with Neptune
(Abridged) New optical colors of 58 objects in mean motion resonances with
Neptune show the various resonant populations have significantly different
color distributions. The 5:3 and 7:4 resonances have semi-major axes near the
middle of the main Kuiper Belt and both are dominated by ultra-red material.
The 5:3 and 7:4 resonances have statistically the same color distribution as
the low inclination "cold" classical belt. The inner 4:3 and distant 5:2
resonances have objects with mostly moderately red colors, similar to the
scattered and detached disk populations. The 2:1 resonance, which is near the
outer edge of the main Kuiper Belt, has a large range of colors with similar
numbers of moderately red and ultra-red objects at all inclinations. The inner
3:2 resonance, like the outer 2:1, has a large range of objects from neutral to
ultra-red. The Neptune Trojans (1:1 resonance) are only slightly red, similar
to the Jupiter Trojans. The inner 5:4 resonance only has four objects with
measured colors but shows equal numbers of ultra-red and moderately red
objects. The 9:5, 12:5, 7:3, 3:1 and 11:3 resonances do not have reliable color
distribution statistics, though it appears noteworthy that all three of the
measured 3:1 objects have only moderately red colors, similar to the 4:3 and
5:2 resonances. The different color distributions are likely a result from the
disruption of the primordial Kuiper Belt from the scattering and migration of
the giant planets. The few low inclination objects known in the outer 2:1 and
5:2 resonances are mostly only moderately red. This suggests if the 2:1 and 5:2
have a cold low inclination component, the objects likely had a significantly
different origin than the ultra-red dominated cold components of the cold
classical belt and 5:3 and 7:4 resonances.Comment: Accepted for publication in The Astronomical Journa
A possible dynamically Cold Classical contact binary: (126719) 2002 CC249
Images of the Kuiper belt object (126719) 2002 CC249 obtained in 2016 and
2017 using the 6.5m Magellan-Baade Telescope and the 4.3m Discovery Channel
Telescope are presented. A lightcurve with a periodicity of 11.87+/-0.01 h and
a peak-to-peak amplitude of 0.79+/-0.04 mag is reported. This high amplitude
double-peaked lightcurve can be due to a single elongated body, but it is best
explained by a contact binary system from its U-/V-shaped lightcurve. We
present a simple full-width-at-half-maximum (FWHM) test that can be used to
determine if an object is likely a contact binary or an elongated object based
on its lightcurve. Considering that 2002 CC249 is in hydrostatic equilibrium, a
system with a mass ratio qmin=0.6, and a density \rho min=1gcc, or less
plausible a system with qmax=1, and \rho max=5gcc can interpret the lightcurve.
Assuming a single Jacobi ellipsoid in hydrostatic equilibrium, and an
equatorial view, we estimate \rho = 0.34gcc, and a/b=2.07. Finally, we report a
new color study showing that 2002 CC249 displays an ultra red surface
characteristic of a dynamically Cold Classical trans-Neptunian object.Comment: In press, The Astronomical Journa
The Plutino population: An Abundance of contact binaries
We observed twelve Plutinos over two separated years with the 4.3m Lowell's
Discovery Channel Telescope. Here, we present the first lightcurve data for
those objects. Three of them (2014JL, 2014JO, 2014JQ)
display a large lightcurve amplitude explainable by a single elongated object,
but are most likely caused by a contact binary system due to their lightcurves
morphology. These potential contact binaries have rotational periods from 6.3h
to 34.9h and peak-to-peak lightcurve variability between 0.6 and 0.8mag. We
present partial lightcurves allowing us to constrain the lightcurve amplitude
and the rotational period of another nine Plutinos. By merging our data with
the literature, we estimate that up to 40 of the Plutinos could be
contact binaries. Interestingly, we found that all the suspected contact
binaries in the 3:2 resonance are small with absolute magnitude H6mag. Based
on our sample and the literature, up to 50 of the small Plutinos are
potential contact binaries.Comment: In press, A
Lightcurves and Rotational Properties of the Pristine Cold Classical Kuiper Belt Objects
We present a survey on the rotational and physical properties of the
dynamically low inclination Cold Classical trans-Neptunian objects. The Cold
Classicals (CCs) are primordial planetesimals and contain relevant information
about the early phase of our Solar System and planet formation over the first
100 million years after the formation of the Sun. Our project makes use of the
Magellan and the Lowell's Discovery Channel Telescopes for photometric
purposes. We obtained partial/complete lightcurves for 42 CCs. We use
statistical tests to derive general properties about the shape and rotational
frequency distributions of the CC population, and infer that the CCs have
slower rotations and are more elongated/deformed than the other trans-Neptunian
objects. Based on the available full lightcurves, the mean rotational period of
the CC population is 9.481.53h whereas the mean period of the rest of the
trans-Neptunian objects is 8.450.58h. About 65% of the trans-Neptunian
objects (excluding the CCs) have a lightcurve amplitude below 0.2mag compared
to the 36% of CCs with small amplitude. We present the full lightcurve of one
new likely contact binary: 2004 VC131 with a potential density of 1gcc for a
mass ratio of 0.4. We also have hints that 2004 MU8 and 2004 VU75 are maybe
potential contact binaries based on their sparse lightcurves but more data are
needed to confirm such a find. Assuming equal-sized binaries, we find that only
~10-25% of the Cold Classicals could be contact binaries, suggesting that there
is a deficit of contact binaries in this population compared to previous
estimates and compared to the abundant (~40-50%) possible contact binaries in
the 3:2 resonant population. This estimate is a lower limit and will increase
if non equal-sized contact binaries are also considered. Finally, we put in
context the early results of the New Horizons flyby of (486958) 2014 MU69.Comment: AJ, In pres
The Reactivation of Main-Belt Comet 324P/La Sagra (P/2010 R2)
We present observations using the Baade Magellan and Canada-France-Hawaii
telescopes showing that main-belt comet 324P/La Sagra, formerly known as P/2010
R2, has become active again for the first time since originally observed to be
active in 2010-2011. The object appears point-source-like in March and April
2015 as it approached perihelion (true anomaly of ~300 deg), but was ~1 mag
brighter than expected if inactive, suggesting the presence of unresolved dust
emission. Activity was confirmed by observations of a cometary dust tail in May
and June 2015. We find an apparent net dust production rate of <0.1 kg/s during
these observations. 324P is now the fourth main-belt comet confirmed to be
recurrently active, a strong indication that its activity is driven by
sublimation. It now has the largest confirmed active range of all likely
main-belt comets, and also the most distant confirmed inbound activation point
at R~2.8 AU. Further observations during the current active period will allow
direct comparisons of activity strength with 324P's 2010 activity.Comment: 5 pages, 3 figures, accepted for publication in MNRAS Letter
Lightcurves of 32 Large Transneptunian Objects
We present observations of 32 primarily bright, newly discovered
Transneptunian objects observable from the Southern Hemisphere during 39 nights
of observation with the 2.5-m telescope at Las Campanas Observatory. Our
dataset includes objects in all dynamical classes, but is weighted towards
Scattered objects. We find 15 objects for which we can fit periods and
amplitudes to the data, and place lightcurve amplitude upper limits on the
other 17 objects. Combining our sample with the larger sample in the
literature, we find a 3-sigma correlation between lightcurve amplitude and
absolute magnitude with fainter objects having larger lightcurve amplitudes. We
looked for correlations between lightcurve and individual orbital properties,
but did not find any statistically significant results. However, if we consider
lightcurve properties with respect to dynamical classification, we find
statistically different distributions between the Classical-Scattered and
Classical-Resonant populations, respectively, with the Classical objects having
larger amplitude lightcurves. The properties of binary lightcurves are largely
consistent with the greater population except in the case of tidally locked
systems. All the Haumea family objects measured so far have measurable
amplitudes and rotation periods le 10 hr suggesting that they are not
significantly different from the larger TNO population. We expect multiple
factors are influencing object rotations: object size dominates lightcurve
properties except in the case of tidal, or proportionally large collisional
interactions with other objects, the influence of the latter being different
for each sub-population. We also present phase curves and colors for some
objects; our values are not significantly different from those presented in the
literature for other samples.Comment: Accepted to AJ. 16 pages, 9 tables, 10 figures. Tables 2 and 4 are
electronic, please contact Susan for copies if desired prior to publication.
Revised version: Fixed typos and updated H-magnitude values discovered to be
offset due to a systematic calibration issue, results unchange
Characterization of High Proper Motion Objects from the Wide-field Infrared Survey Explorer
We present an analysis of high proper motion objects that we have found in a
recent study and in this work with multi-epoch astrometry from the Wide-field
Infrared Survey Explorer (WISE). Using photometry and proper motions from 2MASS
and WISE, we have identified the members of this sample that are likely to be
late type, nearby, or metal poor. We have performed optical and near-infrared
spectroscopy on 41 objects, from which we measure spectral types that range
from M4-T2.5. This sample includes 11 blue L dwarfs and five subdwarfs; the
latter were also classified as such in the recent study by Kirkpatrick and
coworkers. Based on their spectral types and photometry, several of our
spectroscopic targets may have distances of <20 pc with the closest at ~12 pc.
The tangential velocities implied by the spectrophotometric distances and
proper motions indicate that four of the five subdwarfs are probably members of
the Galactic halo while several other objects, including the early-T dwarf WISE
J210529.08-623558.7, may belong to the thick disk.Comment: Astrophysical Journal, in pres
Tracking Neptune's Migration History through High-Perihelion Resonant Trans-Neptunian Objects
Recently, Sheppard et al. (2016) presented the discovery of seven new
trans-Neptunian objects with moderate eccentricities, perihelia beyond 40 AU,
and semimajor axes beyond 50 AU. Like the few previously known objects on
similar orbits, these objects' semimajor axes are just beyond the Kuiper belt
edge and clustered around Neptunian mean motion resonances (MMRs). These
objects likely obtained their observed orbits while trapped within MMRs, when
the Kozai-Lidov mechanism raised their perihelia and weakened Neptune's
dynamical influence. Using numerical simulations that model the production of
this population, we find that high-perihelion objects near Neptunian MMRs can
constrain the nature and timescale of Neptune's past orbital migration. In
particular, the population near the 3:1 MMR (near 62 AU) is especially useful
due to its large population and short dynamical evolution timescale. If Neptune
finishes migrating within ~100 Myrs or less, we predict over 90% of
high-perihelion objects near the 3:1 MMR will have semimajor axes within 1 AU
of each other, very near the modern resonance's center. On the other hand, if
Neptune's migration takes ~300 Myrs, we expect ~50% of this population to
reside in dynamically fossilized orbits over ~1 AU closer to the Sun than the
modern resonance. We highlight 2015 KH162 as a likely member of this fossilized
3:1 population. Under any plausible migration scenario, nearly all
high-perihelion objects in resonances beyond the 4:1 MMR (near 76 AU) reach
their orbits well after Neptune stops migrating and comprise a recently
generated, dynamically active population.Comment: Accepted to ApJ; 15 pages, 13 figures, 1 tabl
2004 TT357: A potential contact binary in the Trans-Neptunian belt
We report photometric observations of the trans-Neptunian object
2004~TT obtained in 2015 and 2017 using the 4.3~m Lowell's Discovery
Channel Telescope. We derive a rotational period of 7.790.01~h and a
peak-to-peak lightcurve amplitude of 0.760.03~mag. 2004 TT
displays a large variability that can be explained by a very elongated single
object or can be due to a contact/close binary. The most likely scenario is
that 2004 TT is a contact binary. If it is in hydrostatic equilibrium,
we find that the lightcurve can be explained by a system with a mass ratio
q=0.450.05, and a density of =2g cm, or less
likely a system with q=0.80.05, and =5g cm.
Considering a single triaxial ellipsoid in hydrostatic equilibrium, we derive a
lower limit to the density of 0.78g cm, and an elongation (a/b) of 2.01
assuming an equatorial view. From Hubble Space Telescope data, we report no
resolved companion orbiting 2004 TT. Despite an expected high fraction
of contact binaries in the trans-Neptunian belt, 2001 QG is the unique
confirmed contact binary in the trans-Neptunian belt, and 2004 TT is
only the second candidate to this class of systems, with 2003 SQ.Comment: In Press, Ap
Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With Moderate Semi-major Axes and Eccentricities
We have been conducting a survey for distant solar system objects beyond the
Kuiper Belt edge (~50 AU) with new wide-field cameras on the Subaru 8 meter and
CTIO 4 meter telescopes. We are interested in the orbits of objects that are
decoupled from the giant planet region in order to understand the structure of
the outer solar system, including whether a massive planet exists beyond a few
hundred AU as first reported by Trujillo and Sheppard (2014). In addition to
discovering extreme trans-Neptunian objects detailed elsewhere, we have found
several objects with high perihelia (q>40 AU) that differ from the extreme and
inner Oort cloud objects due to their moderate semi-major axes (50<a<100 AU)
and eccentricities (e<0.3). Newly discovered objects 2014 FZ71 and 2015 FJ345
have the third and fourth highest perihelia known after Sedna and 2012 VP113,
yet their orbits are not nearly as eccentric or distant. We found several of
these high perihelion but moderate orbit objects and observe that they are
mostly near Neptune mean motion resonances and have significant inclinations
(i>20 degrees). These moderate objects likely obtained their unusual orbits
through combined interactions with Neptune's mean motion resonances and the
Kozai resonance, similar to the origin scenarios for 2004 XR190. We also find
the distant 2008 ST291 has likely been modified by the MMR+KR mechanism through
the 6:1 Neptune resonance. We discuss these moderately eccentric, distant
objects along with some other interesting low inclination outer classical belt
objects like 2012 FH84 discovered in our ongoing survey.Comment: Accepted Astrophysical Journal Letter
- β¦