The History of Everything Part 2: How The Solar System Was Created
Sunday, April 29th 2018
On this episode of SKyTour Radio, we discuss exoplanet J1407b, a possible brown dwarf, with a mass 10-40 times that of Jupiter’s. We also discuss the dust ring around Proxima b and what this could mean in the continuing search for habitable exoplanets.
We also continue with the History of Everything as we explore how the rest of our solar system was created. We look at how our Sun was formed and how that allowed the other planets around it to form.
J1407 is a star similar to the Sun in the constellation Centaurus at a distance of about 420 light years from Earth. Its age is estimated to be 16 million years,and its mass is about 90% that of the Sun’s. The star has an apparent magnitude of 12.3 and requires a telescope to be seen.
The low-mass companion J1407b has been referred to as a “Saturn on steroids”or “Super Saturn” due to its massive system of circum-planetary rings with a radius of approximately 90 million km.
The orbital period of J1407b is estimated to be between 3.5 to 13.8 years, and its most probable mass is approximately 13 to 26 Jupiter masses, but with considerable uncertainty.
J1407b is the first exoplanet or brown dwarf discovered with a ring system by the transit method. A sequence of occultations (eclipses) of the star occurred over a 56-day period in 2007. The pattern was consistent with that expected for the transit of a large array of multiple rings, indicating the substellar companion dubbed “J1407b”.
The J1407b ring system has an outer radius of about 90 million km (about 640 times the one of Saturn’s rings) and cleared gaps in the rings indicate satellites(“exo-moons”) have formed accreted from denser rings.
The young age of the stellar system (about 16 million years) and the high mass of the ring system (roughly an Earth mass) are more consistent with it being an early (proto-)exo-moon or moons, rather than a long-term stable ring system in an evolved planetary system (such as Saturn’s rings).
Proxima b is an exoplanet orbiting within the habitable zone of the closest star to the Sun—the red dwarf star Proxima Centauri, which is in a triple star system and is located about 4.2 light-years from Earth in the constellation of Centaurus, making it the closest known exoplanet to the Solar System.
The discovery of the planet was announced in August 2016 by the European Southern Observatory using the radial velocity method, where periodic Doppler shifts of spectral lines of the host star suggest an orbiting object.
Proxima Centauri b orbits the star at a distance of roughly 0.05 AU with an orbital period of approximately 11.2 Earth days, and has an estimated mass of at least 1.3 times that of the Earth.
Its habitability has not been established, though it is unlikely to be habitable since the planet is subject to stellar wind pressures of more than 2,000 timesthose experienced by Earth from the solar wind, however according to Guillem Anglada‐Escudé, its proximity to Earth offers an opportunity for robotic exploration of the planet with the Starshot project or, at least, “in the coming centuries”
It is unlikely that Proxima Centauri b originally formed in its current orbit since disk models for small stars like Proxima Centauri would contain less than one M⊕ of matter within the central one AU at the time of their formation.
This implies that either Proxima Centauri b was formed elsewhere in a manner still to be determined, or the current disc models for stellar formation are in need of revision.
The Solar System
The Solar System is the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest eight are the planets, with the remainder being smaller objects, such as dwarf planets and small Solar System bodies.
Formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud, the vast majority of the system’s mass is in theSun, with the majority of the remaining mass contained in Jupiter.
The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials.
The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.
The asteroid belt, which lies between the orbits of Mars and Jupiter, mostly contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptune’s orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, and beyond them a newly discovered population of sednoids. Within these populations are several dozen to possibly tens of thousands of objects large enough that they have been rounded by their own gravity. Such objects are categorized as dwarf planets. Identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris.
All this and more on this episode of Sky Tour Radio. By understanding what came before us, we can look for similar formation through the universe.
SkyTour Radio explores the Universe in a down to Earth manner explaining the science we know in fun and bite-sized terms. Science is for everyone and people shouldn’t require an advanced degree to understand as long as it is delivered in an easy to follow way. From Black Holes to Extraterrestrial Life, we will explore the Universe like never before. Join us to check out such things as how stars form, how they live and, how our fate is intertwined with theirs. On the extraterrestrial life front, we will be speaking to the UFO and science arena’s top researchers and bring UFOlogy into the 21st century.
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