3,706 research outputs found
Discovery of a planetary-sized object in the scattered Kuiper belt
We present the discovery and initial physical and dynamical characterization
of the object 2003 UB313. The object is sufficiently bright that for all
reasonable values of the albedo it is certain to be larger than Pluto.
Pre-discovery observations back to 1989 are used to obtain an orbit with
extremely small errors. The object is currently at aphelion in what appears to
be a typical orbit for a scattered Kuiper belt object except that it is
inclined by about 44 degrees from the ecliptic. The presence of such a large
object at this extreme inclination suggests that high inclination Kuiper belt
objects formed preferentially closer to the sun. Observations from Gemini
Observatory show that the infrared spectrum is, like that of Pluto, dominated
by the presence of frozen methane, though visible photometry shows that the
object is almost neutral in color compared to Pluto's extremely red color. 2003
UB313 is likely to undergo substantial seasonal change over the large range of
heliocentric distances that it travels; Pluto at its current distance is likely
to prove a useful analog for better understanding the range of seasonal changes
on this body.Comment: 9 pages, 1 figur
Dependence of Maximum Trappable Field on Superconducting Nb3Sn Cylinder Wall Thickness
Uniform dipole magnetic fields from 1.9 to 22.4 kOe were permanently trapped,
with high fidelity to the original field, transversely to the axes of hollow
Nb3Sn superconducting cylinders. These cylinders were constructed by helically
wrapping multiple layers of superconducting ribbon around a mandrel. This is
the highest field yet trapped, the first time trapping has been reported in
such helically wound taped cylinders, and the first time the maximum trappable
field has been experimentally determined as a function of cylinder wall
thickness.Comment: 8 pages, 4 figures, 1 table. PACS numbers: 74.60.Ge, 74.70.Ps,
41.10.Fs, 85.25.+
Quaoar: A Rock in the Kuiper belt
Here we report WFPC2 observations of the Quaoar-Weywot Kuiper belt binary.
From these observations we find that Weywot is on an elliptical orbit with
eccentricity of 0.14 {\pm} 0.04, period of 12.438 {\pm} 0.005 days, and a
semi-major axis of 1.45 {\pm} 0.08 {\times} 104 km. The orbit reveals a
surpsingly high Quaoar-Weywot system mass of 1.6{\pm}0.3{\times}10^21 kg. Using
the surface properties of the Uranian and Neptunian satellites as a proxy for
Quaoar's surface, we reanalyze the size estimate from Brown and Trujillo
(2004). We find, from a mean of available published size estimates, a diameter
for Quaoar of 890 {\pm} 70 km. We find Quaoar's density to be \rho = 4.2 {\pm}
1.3 g cm^-3, possibly the highest density in the Kuiper belt.Comment: 11 pages, 2 figures, accepted for publication in ApJ letters
Periods, Organized (PeriodO): A gazetteer of period assertions for linking and visualizing periodized data
The PeriodO project seeks to create an online gazetteer of authoritative assertions about the chronological and geographic extent of historical and archaeological periods. Starting with a trial dataset related to Classical antiquity, this gazetteer will combine period thesauri used by museums and cultural heritage bodies with published assertions about the dates and locations of periods in authoritative print sources. These assertions will be modeled in a Linked Data format (JSON-LD, a serialization of RDF). They will be given Uniform Resource Identifiers (URIs) and served from a public GitHub repository, where they can act as a shared reference point to describe data in datasets with periodized information. We will also create a search and visualization tool to view the temporal and geographic extent of an assertion and compare it with others. Authoritative users will be able to add their own period assertions
Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope
We have used the Hubble Space Telescope to directly measure the angular size
of the large Kuiper belt object 2003 UB313. By carefully calibrating the point
spread function of a nearby field star, we measure the size of 2003 UB313 to be
34.31.4 milliarcseconds, corresponding to a diameter of 2400100 km or
a size % larger than Pluto. The V band geometric albedo of 2003 UB313 is
%. The extremely high albedo is consistent with the frosty methane
spectrum, the lack of red coloring, and the lack of observed photometric
variation on the surface of 2003 UB313. Methane photolysis should quickly
darken the surface of 2003 UB313, but continuous evaporation and redeposition
of surface ices appears capable of maintaining the extreme alebdo of this body
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