7,082 research outputs found
Candidate Members and Age Estimate of the Family of Kuiper Belt Object 2003 EL61
The collisional family of Kuiper belt object (KBO) 2003 EL61 opens the
possibility for many interesting new studies of processes important in the
formation and evolution of the outer solar system. As the first family in the
Kuiper belt, it can be studied using techniques developed for studying asteroid
families, although some modifications are necessary. Applying these modified
techniques allows for a dynamical study of the 2003 EL61 family. The velocity
required to change orbits is used to quantitatively identify objects near the
collision. A method for identifying family members that have potentially
diffused in resonances (like 2003 EL61) is also developed. Known family members
are among the very closest KBOs to the collision and two new likely family
members are identified: 2003 UZ117 and 1999 OY3. We also give tables of
candidate family members which require future observations to confirm
membership. We estimate that a minimum of ~1 GYr is needed for resonance
diffusion to produce the current position of 2003 EL61, implying that the
family is likely primordial. Future refinement of the age estimate is possible
once (many) more resonant objects are identified. The ancient nature of the
collision contrasts with the seemingly fresh surfaces of known family members,
suggesting that our understanding of outer solar system surfaces is incomplete.Comment: 22 pages, 5 figures, accepted to AJ, author's cv available at
http://www.gps.caltech.edu/~dari
The earth's trapped radiation belts
The near-earth charged particle environment is discussed in terms of spacecraft design criteria. Models are presented of the trapped radiation belts and based on in-situ data obtained from spacecraft
The Orbit, Mass, and Albedo of Transneptunian Binary 1999 RZ253
We have observed 1999 RZ253 with the Hubble Space Telescope at seven separate
epochs and have fit an orbit to the observed relative positions of this binary.
Two orbital solutions have been identified that differ primarily in the
inclination of the orbit plane. The best fit corresponds to an orbital period,
P=46.263 +0.006/-0.074 days, semimajor axis a=4,660 +/-170 km and orbital
eccentricity e=0.460 +/-0.013 corresponding to a system mass m=3.7 +/-0.4
x10^18 kg. For a density of rho = 1000 kg m^-3 the albedo at 477 nm is p = 0.12
+/-0.01, significantly higher than has been commonly assumed for objects in the
Kuiper Belt. Multicolor, multiepoch photometry shows this pair to have colors
typical for the Kuiper belt with a spectral gradient of 0.35 per 100 nm in the
range between 475 and 775 nm. Photometric variations at the four epochs we
observed were as large as 12 +/-3% but the sampling is insufficient to confirm
the existence of a lightcurve
Theoretical dynamic analysis of the landing loads on a vehicle with a tricycle landing gear
Theoretical dynamic analysis of landing loads on vehicle with tricycle landing gear compared with X-15 aircraft dat
A deep i-selected multi-waveband galaxy catalogue in the COSMOS field
In this paper we present a deep and homogeneous i-band selected
multi-waveband catalogue in the COSMOS field covering an area of about 0.7
square-degree. Our catalogue with a formal 50 percent completeness limit for
point sources of i~26.7 comprises about 290.000 galaxies with information in 8
passbands. We combine publicly available u, B, V, r, i, z, and K data with
proprietary imaging in H band. We discuss in detail the observations, the data
reduction, and the photometric properties of the H-band data. We estimate
photometric redshifts for all the galaxies in the catalogue. A comparison with
162 spectroscopic redshifts in the redshift range 0 < z < 3 shows that the
achieved accuracy of the photometric redshifts is (Delta_z / (z_spec+1)) ~0.035
with only ~2 percent outliers. We derive absolute UV magnitudes and investigate
the evolution of the luminosity function evaluated in the rest-frame UV at 1500
Angstrom. There is a good agreement between the LFs derived here and the LFs
derived in the FORS Deep Field. We see a similar brightening of M_star and a
decrease of phi_star with redshift. The catalogue including the photometric
redshift information is made publicly available.Comment: 20 pages, 17 figures, accepted for publication in MNRAS; high
resulution paper: http://www.mpe.mpg.de/~gabasch/COSMOS/cosmos.pd
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