Merging Black Holes and Neutron Stars. All the Gravitational Wave Events Seen So Far in One Picture

The mergers of compact objects discovered so far by LIGO and Virgo (in O1, O2 and O3a). The diagram shows black holes (blue), neutron stars (orange) and compact objects of unknown nature (grey), which were detected by their gravitational-wave emission. Each merger of a binary system corresponds to three compact objects shown: the two merging objects and the result of the merger. A selection of black holes (violet) and neutron stars (yellow) discovered by electromagnetic observations is shown for comparison. Image Credit: LIGO Virgo Collaboration / Frank Elavsky, Aaron Geller / Northwestern

The Theory of Relativity predicted the existence of black holes and neutron stars. Einstein gets the credit for the theory because of his paper published in 1915, even though other scientists’ work helped it along. But regardless of the minds behind it, the theory predicted black holes, neutron stars, and the gravitational waves from their mergers.

It took about one hundred years, but scientists finally observed these mergers and their gravitational waves in 2015. Since then, the LIGO/Virgo collaboration has detected many of them. The collaboration has released a new catalogue of discoveries, along with a new infographic. The new infographic displays the black holes, neutron stars, mergers, and the other uncertain compact objects behind some of them.

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New Horizons Saw the Universe With Even Less Light Pollution than Hubble’s View

Artist's impression of New Horizons' close encounter with the Pluto–Charon system. Credit: NASA/JHU APL/SwRI/Steve Gribben

In July of 2015, NASA’s New Horizons probe made history when it became the first mission ever to conduct a close flyby of Pluto. This was followed by the spacecraft making the first-ever encounter with a Kuiper Belt Object (KBO) – known as Arrokoth (aka. 2014 MU69) – on Dec.31st, 2018. In addition, its unique position in the outer Solar System has allowed astronomers to conduct rare and lucrative science operations.

This has included parallax measurements of Proxima Centauri and Wolf 359, the two closest stars to the Solar System. In addition, a team of astronomers led by the National Optical Astronomy Observatory (NOAO) and Southwest Research Institute (SwRI) used archival data from the probe’s Long Range Reconnaissance Imager (LORRI) to conduct measurements of the Cosmic Optical Background (COB).

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There are Planets So Close to Their Stars That They Have Magma Oceans 100km Deep and Winds that Go 8000 km/h

Artist's impression of a lava world. The exoplanet K2-141b is so close to its host star that it likely has magma oceans and surface temperatures over 3000 degrees. It's possible water is mixed in with the magma. c. ESO
Artist's impression of a lava world. The exoplanet K2-141b is so close to its host star that it likely has magma oceans and surface temperatures over 3000 degrees. It's possible water is mixed in with the magma. c. ESO

200 light years away, “super earth” exoplanet K2-141b orbits a star so closely that its “year” is only 7 hours long. Not its day…its YEAR! K2-141b orbits a mere million kilometers from the fiery surface of its star. Earth is 150 million km from our Sun. Even Mercury, the planet closest to our Sun, is never less than 47 million km. Standing on the surface of K2-141b you’d look up at an orange star that filled fifty degrees of the sky appearing a hundred times wider than our Sun appears in Earth’s sky. It would be a giant blazing orb so bright that its light shines two thirds of the way around the entire planet unlike Earth’s two day/night halves. Of course, the surface you’re standing on wouldn’t be much of a surface at all – it would be an ocean of liquid hot magma.

Artist’s impression of a close orbiting exoplanet around a star. c. ESO
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SpaceX’s Resilience Spacecraft has Lifted Off and is Headed for the ISS!

The crew of the NASA/SpaceX Crew-1 flight. Credit: SpaceX

Earlier this evening (Sunday, November 15th, 2020), NASA and SpaceX achieved another historical milestone. Six months after successfully sending astronauts Robert Behnken and Douglas Hurley to the ISS with the Demo-2 mission, the US demonstrated the restoration of domestic launch capability by sending the fully-crewed Crew Dragon spacecraft (Resilience) on an operational mission to the ISS.

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What Role do Radioactive Elements Play in a Planet’s Habitability?

Illustration of Kepler-186f, a recently-discovered, possibly Earthlike exoplanet that could be a host to life. (NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)
This is Kepler 186f, an exoplanet in the habitable zone around a red dwarf. We've found many planets in their stars' habitable zones where they could potentially have surface water. But it's a fairly crude understanding of true habitability. Image Credit: NASA Ames, SETI Institute, JPL-Caltech, T. Pyle)

To date, astronomers have confirmed the existence of 4,301 extrasolar planets in 3,192 star systems, with another 5,650 candidates awaiting confirmation. In the coming years, next-generation telescopes will allow astronomers to directly observe many of these exoplanets and place tighter constraints on their potential habitability. In time, this could lead to the discovery of life beyond our Solar System!

The only problem is, finding evidence of life requires that we know what to look for. According to a new study by an interdisciplinary team of scientists from the University of California Santa Cruz (UCSC), radioactive elements might play a role in planetary habitability. Future studies of rocky exoplanets, they argue, should therefore look for specific isotopes that indicate the presence of long-lived elements like thorium and uranium.

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The Average Temperature of the Universe has Been Getting Hotter and Hotter

An illustration of cosmic expansion. Credit: NASA's Goddard Space Flight Center Conceptual Image Lab

For almost a century, astronomers have understood that the Universe is in a state of expansion. Since the 1990s, they have come to understand that as of four billion years ago, the rate of expansion has been speeding up. As this progresses, and the galaxy clusters and filaments of the Universe move farther apart, scientists theorize that the mean temperature of the Universe will gradually decline.

But according to new research led by the Center for Cosmology and AstroParticle Physics (CCAPP) at Ohio State University, it appears that the Universe is actually getting hotter as time goes on. After probing the thermal history of the Universe over the last 10 billion years, the team concluded that the mean temperature of cosmic gas has increased more than 10 times and reached about 2.2 million K (~2.2 °C; 4 million °F) today.

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Venus Held Onto its Water Surprisingly Well During its History

Artist's impression of Venus with the solar wind flowing around the planet, which has little magnetic protection. Venus Express found that a lot of water has bled into space over the years from the planet, which happens when the sun's ultraviolet radiation breaks oxygen and hydrogen molecules apart and pushes them into space. Credit: ESA - C. Carreau

Named for the ancient goddess of fertility, the planet Venus could not be more hostile to life as we know it. Aside from being the hottest planet in the Solar System, Venus has also an atmosphere that is 92 times denser than Earth’s, and regularly experiences sulfuric acid rain. But as we’ve learned from multiple surveys, Venus was once a much milder climate and even had vast oceans on its surface.

For astronomers and geologists alike, the burning question is, how much of its water did Venus hold onto during this massive transition? According to research presented by Moa Persson of the Swedish Institute of Space Physics (IRF), Venus actually retained most of its water over the past 4 billion years. Contrary to what researchers previously thought, Venus lost only a small amount of its water to a runaway Greenhouse Effect.

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Do neutron star collisions produce black holes?

neutron star merger and gamma ray burst
Artistic representation of two merging neutron stars. Credit: Dana Berry, SkyWorks Digital, Inc.

In principle, creating a stellar-mass black hole is easy. Simply wait for a large star to reach the end of its life, and watch its core collapse under its own weight. If the core has more mass than 2 – 3 Suns, then it will become a black hole. Smaller than about 2.2 solar masses and it will become a neutron star. Smaller than 1.4 solar masses and it becomes a white dwarf.

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Europa’s Nightside Glows in the Dark

This illustration of Jupiter's moon Europa shows how the icy surface may glow on its nightside, the side facing away from the Sun. Variations in the glow and the color of the glow itself could reveal information about the composition of ice on Europa's surface. Credit: NASA/JPL-Caltech

In a few years, NASA will be sending a spacecraft to explore Jupiter’s icy moon Europa. Known as the Europa Clipper mission, this orbiter will examine the surface more closely to search for plume activity and evidence of biosignatures. Such a find could answer the burning question of whether or not there is life within this moon, which is something scientists have speculated about since the 1970s.

In anticipation of this mission, scientists continue to anticipate what it will find once it gets there. For instance, scientists from NASA’s Jet Propulsion Laboratory recently conducted a study that showed how Europa might glow in the dark. This could be the result of Europa constantly being pummeled with high-energy radiation from Jupiter’s magnetic field, the study of which could tell scientists more about the composition of Europa’s ice.

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