Across The Universe, Cont. - Colliding Neutron Stars Produce Gamma Ray Bursts And Gravitational Waves

(click on image to enlarge)



From NASA, October 16, 2017: On August 17, 2017, the Laser Interferometer Gravitational-wave Observatory detected gravitational waves from a neutron star collision. Within 12 hours, observatories had identified the source of the event within the galaxy NGC 4993, shown in this Hubble Space Telescope image, and located an associated stellar flare called a kilonova (box). Inset: Hubble observed the kilonova fade over the course of six days. Credits: NASA and ESA

The significance of this observation, briefly:

In August, for the first time ever, scientists witnessed the electromagnetic lightning and gravitational gusts from the stormy collision of two neutron stars in a distant galaxy. The cosmic cataclysm created a “kilonova” — a phenomenon that had never been seen before — and the observations by both traditional telescopes and gravitational wave detectors heralded a new era for science. In the years to come, astrophysicists will use two “messengers” to understand the universe: electromagnetism and gravity. 

The effort to capture the event's fleeting signals involved three gravitational wave detectors, more than five dozen telescopes on every continent including Antarctica, seven space-based observatories, and, according to one estimate, 15 percent of the world's astronomers. It yielded 20 scientific papers published in three separate journals and answered a broad array of questions about the cosmos: What happens when neutron stars collide? How are precious elements like gold produced? Where do some bursts of high-energy gamma rays originate? 

Those discoveries are just the beginning: “This is opening a new brand of research and science,” Eleonora Troja, an astrophysicist at NASA's Goddard Space Flight Center and the University of Maryland, said Tuesday.

The article continues with a discussion of how this detection will change the course of astronomy.

More here from NASA (including more images of the neutron star collision).

Cassini: Countdown To Oblivion

It was a glorious ride.

NASA's Cassini spacecraft carrying ESA's Huygens probe was launched on October 15, 1997, and is arguably the most successful space exploration mission ever.  In just under three days from now, it will complete its decades- long mission by entering the atmosphere of Saturn and disintegrating, completing what NASA is calling "The Grand Finale." NASA describes the journey:

Beginning in 2010, Cassini began a seven-year mission extension in which it completed many moon flybys while observing seasonal changes on Saturn and Titan. The plan for this phase of the mission was to expend all of the spacecraft's propellant while exploring Saturn, ending with a plunge into the planet's atmosphere. In April 2017, Cassini was placed on an impact course that unfolded over five months of daring dives—a series of 22 orbits that each pass between the planet and its rings. Called the Grand Finale, this final phase of the mission has brought unparalleled observations of the planet and its rings from closer than ever before. 

On Sept. 15, 2017, the spacecraft will make its final approach to the giant planet Saturn. But this encounter will be like no other. This time, Cassini will dive into the planet's atmosphere, sending science data for as long as its small thrusters can keep the spacecraft's antenna pointed at Earth. Soon after, Cassini will burn up and disintegrate like a meteor. 

To its very end, Cassini is a mission of thrilling exploration. Launched on Oct. 15, 1997, the mission entered orbit around Saturn on June 30, 2004 (PDT), carrying the European Huygens probe. After its four-year prime mission, Cassini's tour was extended twice. Its key discoveries have included the global ocean with indications of hydrothermal activity within Enceladus, and liquid methane seas on Titan. 

And although the spacecraft may be gone after the finale, its enormous collection of data about Saturn—the giant planet itself, its magnetosphere, rings and moons—will continue to yield new discoveries for decades.

It took Cassini 7 years to arrive at Saturn, where it then spent more than a decade touring the ringed planet and its intriguing moons.

Why does Cassini matter so much? Here are 9 ways.  It's enough to make one proud to be of the human species, and of the belief we can do "big things."  It's an achievement to be applauded and emulated.

Here's a video depiction from NASA on Cassini and its "Grand Finale:"