Instituto Argentino Of Glaciologia Y Nivologia Ianigla

Mendoza, Argentina

Instituto Argentino Of Glaciologia Y Nivologia Ianigla

Mendoza, Argentina
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Branham Jr. R.L.,Instituto Argentino Of Glaciologia Y Nivologia Ianigla
Planetary and Space Science | Year: 2012

Comets C/1854 P1 (Brorsen) and C/1851 U1 (Brorsen) are one of a large number of comets with parabolic orbits. Given that there are sufficient observations of the comet, 183 in right ascension and 183 in declination for the former and 47 in both coordinates for the latter, it proves possible to calculate better orbits. The C/1851 P1s orbit is a highly eccentric ellipse, although statistically distinguishable from a parabola. The comet will not return for another 18,000 years and will pass at a minimum distance of 0.986 AU from the Earth. This object, therefore, cannot be considered an NEO. C/1851 U1s orbit is a hyperbola, but with no indication of a possible extrasolar origin. © 2012 Published by Elsevier Ltd.

Branham Jr. R.L.,Instituto Argentino Of Glaciologia Y Nivologia Ianigla
Planetary and Space Science | Year: 2013

Comet C/1854 L1 (Klinkerfues) is one of a large number of comets with parabolic orbits. Given that there are sufficient observations of the comet, 262 in right ascension and 260 in declination, it proves possible to calculate a better orbit. The calculations are based on a 12th order predictor-corrector method. The comet's orbit is highly elliptical, e=0.99866 and, from calculated mean errors, statistically different from a parabola. The comet will not return for at least 10,400 years and thus represents no immediate NEO threat. © 2013 Elsevier Ltd.

Branham R.L.,Instituto Argentino Of Glaciologia Y Nivologia Ianigla
Astrophysics and Space Science | Year: 2015

The distance from the sun to the center of the Galaxy R0$R_{0}$ remains a fundamental parameter for Galactic structure. This study uses 36,061 A and F stars of all luminosity classes with position, parallax, and proper motion taken from the Hipparcos catalog and radial velocities from the Wilson and Strasbourg Data Center catalogs. The nonlinear kinematical equations of condition are solved by the Nelder–Mead simplex algorithm and give R0=7.68±0.07kpc$R_{0}=7.68\pm 0.07~\mbox{kpc}$. The randomness of the residuals, calculated by a runs test as 91.9 % probable, shows that the kinematical model yields satisfactory results. © 2015, Springer Science+Business Media Dordrecht.

Branham R.L.,Instituto Argentino Of Glaciologia Y Nivologia Ianigla
Planetary and Space Science | Year: 2014

Comets C/1848 P1 (Petersen) and C/1848 U1 (Petersen) are ones of a large number of comets with parabolic orbits. Given that there are sufficient observations, 67 in right ascencion and 61 in declination for the former and 144 in right ascension and 144 in declination for the latter, it proves to be possible to calculate better orbits. The C/1848 P1s orbit is hyperbolic, although statistically indistinguishable from a parabola. This object, therefore, cannot be considered as an NEO. C/1848 U1s orbit is also hyperbolic, but with no indication of a possible extrasolar origin. © 2013 Elsevier Ltd. All rights reserved.

Branham Jr. R.L.,Instituto Argentino Of Glaciologia Y Nivologia Ianigla
Astrophysics and Space Science | Year: 2014

The OB stars are concentrated near the Galactic plane and should permit a determination of the distance to the Galactic center. van Leeuwen's new reduction of the Hipparcos catalog provides, after 824 Gould belt stars have been excluded, 6288 OB stars out to 1 kpc and Westin's compilation an additional 112 stars between 1 kpc and 3 kpc. The reduction model involves 14 unknowns: the Oort A and B constants, the distance to the Galactic center R0, 2 second-order partial derivatives, the 3 components of solar motion, a K term, a first order partial derivative for motion perpendicular to the Galactic plane, a second-order partial for acceleration perpendicular to the plane, two terms for a possible expansion of the OB stars, and a C constant. The model is nonlinear, and the unknowns are calculated by use the simplex algorithm for nonlinear adjustment applied to 14313 equations of condition, 12694 in proper motion and 1619 in radial velocity. Various solutions were tried: an L1 solution, a least squares solution with modest (2.7 %) trim of the data, and two robust least squares solutions (biweight and Welsch weighting) with more extreme trimming. The Welsch solution seems to give the best results and calculates a distance to the Galactic center 6.72±0.39 kpc. Statistical tests show that the data are homogeneous, that the reduction model seems adequate and conforms with the assumptions used in its derivation, and that the post-fit residuals are random. Inclusion of more terms, such as streaming motion induced by Galactic density waves, degrades the solution. © 2014 Springer Science+Business Media Dordrecht.