2001.08748
A galactic-scale gas wave in the Solar neighborhood
Alves, et al
For the past 150 years, the prevailing view of the local Interstellar Medium (ISM) was based on a peculiarity known as the Gould's Belt, an expanding ring of young stars, gas, and dust, tilted about 20$^\circ$ to the Galactic plane. Still, the physical relation between local gas clouds has remained practically unknown because the distance accuracy to clouds is of the same order or larger than their sizes. With the advent of large photometric surveys and the Gaia satellite astrometric survey this situation has changed. Here we report the 3-D structure of all local cloud complexes. We find a narrow and coherent 2.7 kpc arrangement of dense gas in the Solar neighborhood that contains many of the clouds thought to be associated with the Gould Belt. This finding is inconsistent with the notion that these clouds are part of a ring, disputing the Gould Belt model. The new structure comprises the majority of nearby star-forming regions, has an aspect ratio of about 1:20, and contains about 3 million solar masses of gas. Remarkably, the new structure appears to be undulating and its 3-D distribution is well described by a damped sinusoidal wave on the plane of the Milky Way, with an average period of about 2 kpc and a maximum amplitude of about 160 pc. Our results represent a first step in the revision of the local gas distribution and Galactic structure and offer a new, broader context to studies on the transformation of molecular gas into stars.
2001.09150
The orbit of Planet Nine derived from engineering physics
Finch, Galiazzo
Several papers have recently suggested the possible presence of a ninth planet (Planet X) that might explain the gravitational perturbations of a number of detached Trans-Neptunian objects. To analyze the possibility further, we have applied celestial mechanics, engineering physics and statistical analysis to develop improved estimates of the planet's primary orbital elements and mass from first engineering principles, using the orbital characteristics of both the original group of 6 objects analyzed and also a second group comprising the original 6 together with 6 additional long-period asteroids selected by the authors. We show that the driving force behind the observed clustering is gravitational torque that arranges the orbits of asteroids in a systematic, orderly manner, and we develop the associated equations of motion. As evidence we show that the expected effects are fully apparent in the orbital characteristics of the correlated bodies involved, including most strikingly regarding their orbital planes, azimuth orientations and specific relative angular momenta, which we show generates a highly unexpected form of resonance in their relative angular momenta. We further show that the coordinates of Planet 9's orbit are close to the original values proposed recently by other authors, although we prove that its period has to be dramatically smaller than that proposed in recent literature by Batygin and Brown, 2019, at about 3500 yrs, the eccentricity is near 0.65, and its mass approximately 8.4 times the Earth's mass. Given the predicted orbit we show that the planet has apparently created numerous mean motion resonances, of which seven are noted specifically. As for a possible observation, Planet X, would range between V=18.9 and 26.1, probably with a magnitude of about 24.8.
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