March 11th, 2017
In this episode of SkyTour Radio, we continue with our weekly Exoplanet Round up where we will discuss the binary star HR4796 as well as focus on WASP-39b, which is being called a “hot Saturn”
We will also be presenting examples of how truly dangerous the universe can be, by taking a closer look at zombie stars and hypernovae.
A binary star system in the southern constellation of Centaurus, HR 4796 lying 237 light-years from the Earth.
The two components of this system have an angular separation of 7.7 arc seconds, or 560 times the separation of the Earth from the Sun.
The luminosity class of ‘V’ indicates that both stars belong to the main sequence and are generating energy through the thermonuclear fusion of hydrogen at their cores.
The star and its ring resemble an eye, giving it the nickname “Sauron’s Eye”
Located in the Virgo constellation, WASP-39b is a “hot Saturn” extra solarplanet discovered in 2011 by the WASP project, (Wide Angle Search for Planets) and lies about 700 light-years from Earth with a mass of about 0.28 times that of Jupiter, and a radius about 1.27 times that of Jupiter.
The exoplanet orbits WASP-39, its host star, every 4 days and in a 2018 study, WASP 39b was found to have hot water molecules the atmosphere. WASP-39b also has an extremely low density.
A zombie star is a hypothetical result of a Type Iax supernova which leaves behind a remnant star, rather than completely dispersing the stellar mass.
In a binary system consisting of a white dwarf and a companion star, the white dwarf strips away material from its companion. Normally the white dwarf would eventually reach a critical mass, and fusion reactions would make it explode and completely dissipate it, but in a Type Iax supernova, only half of the dwarf’s mass is lost.
A hypernova (alternatively called a collapsar) is a very energetic supernova thought to result from an extreme core-collapse scenario. In this case a massive star (>30 solar masses) collapses to form a rotating black hole emitting twin energetic jets and surrounded by an accretion disk.
A wide variety of causes have been proposed to explain events that are anorder of magnitude or more greater than standard supernovae. The collapsar and CSM (circumstellar material) models are generally accepted and a number of events are well-observed. Other models are still only tentatively accepted or remain entirely theoretical, including Pair-instability supernova and Magnetar energy release.
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