neutron stars tagged posts

Gravitational-wave emission from a collapsing star

Astrophysicists at Goethe University Frankfurt set a new limit for the maximum mass of neutron stars: It cannot exceed 2.16 solar masses. Since their discovery in the 1960s, scientists have sought to answer an important question: How massive can neutron stars actually become? By contrast to black holes, these stars cannot gain in mass arbitrarily; past a certain limit there is no physical force in nature that can counter their enormous gravitational force.

With a radius of about 12 km and a mass that can be twice as large as that of the sun, neutron stars are amongst the densest objects in the Universe, producing gravitational fields comparable to those of black holes. Whilst most neutron stars have a mass of around 1...

Artist’s depiction of a neutron star. Credit Credit: NASA

Astronomers like to say we are the byproducts of stars, stellar furnaces that long ago fused hydrogen and helium into the elements needed for life through the process of stellar nucleosynthesis. As the late Carl Sagan once put it: “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of star stuff.” But what about the heavier elements in the periodic chart, elements such as gold, platinum and uranium?

Astronomers believe most of these “r-process elements” – elements much heavier than iron – were created, either in the aftermath of the collapse of massive stars and the associated supernova explosions, or in the merging of b...

An artist’s impression of a millisecond pulsar and its companion. The pulsar (seen in blue with two radiation beams) is accreting material from its bloated red companion star and increasing its rotation rate. Astronomers have measured the orbital parameters of four millisecond pulsars in the globular cluster 47 Tuc and modeled their possible formation and evolution paths. Credit: European Space Agency & Francesco Ferraro (Bologna Astronomical Observatory)

When a star with a mass of roughly 10 solar masses finishes its life, it explodes as a supernova, leaving behind a neutron star as remnant “ash.” Neutron stars have masses of one-to-several suns but they are tiny in diameter, only tens of kilometers...

This is an image of Reticulum II obtained by the Dark Energy Survey, using the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory. The nine stars described in the paper are circled in red. The insets show the very strong presence of barium, one of the main neutron capture elements the team observed, in three stars. Background image is courtesy of Dark Energy Survey/Fermilab. Foreground image is courtesy of Alexander Ji, Anna Frebel, Anirudh Chiti, and Josh Simon. Credit: Background image is courtesy of Dark Energy Survey/Fermilab. Foreground image is courtesy of Alexander Ji, Anna Frebel, Anirudh Chiti, and Josh Simon.

The lightest few elements in the periodic table formed minutes after the Big Bang...