Astrophysicist proposes new definition of a planet

22 January 2018 Astronomy Now

Pluto hogs the spotlight in the continuing scientific debate over what is and what is not a planet, but a less conspicuous argument rages on about the planetary status of massive objects outside our solar system. The dispute is not just about semantics, as it is closely related to how giant planets like Jupiter form.


Light echoes reveal supermassive black holes eating stars

17 September 2016 Astronomy Now

When a star passes within a certain distance of a black hole, the stellar material gets stretched and compressed as the black hole swallows it, briefly releasing an enormous amount of energy as a flare. Astronomers have now observed infrared light echoes from these “stellar tidal disruption” events reflected by dust encircling a black hole.


Did gravitational wave detector find dark matter?

16 June 2016 Astronomy Now

A matter of scientific speculation since the 1930s, dark matter itself cannot yet be detected, but its gravitational effects can be. Now, eight scientists from Johns Hopkins University consider the possibility that the first black hole binary detected by LIGO could be part of this mysterious substance known to make up about 85 percent of the mass of the universe.


Stars nearly as old as Sun found to have similar spin rates

17 May 2016 Astronomy Now

Astrophysicists from Germany and America have for the first time measured the rotation periods of stars in a cluster nearly as old as the Sun. It turns out that these stars spin once in about twenty-six days — just like our Sun. This discovery significantly strengthens what is known as the solar-stellar connection, a fundamental principle that guides much of modern solar and stellar astrophysics.


New research shows quasars slowed pace of star formation

24 March 2016 Astronomy Now

Galaxies reached their busiest star-making pace about 11 billion years ago, then slowed down. Scientists have puzzled for years over the question of what happened. Now researchers have found evidence supporting the argument that the answer was energy feedback from quasars within the galaxies where stars are born.


Merging galaxies break radio silence

29 May 2015 Astronomy Now

A large Hubble survey confirms an unambiguous link between the presence of supermassive black holes that power high-speed, radio-signal-emitting jets and the merger history of their host galaxies. The results lend significant weight to the case for jets being the result of merging black holes.


Delta Cephei’s secret companion and intriguing past

13 May 2015 Astronomy Now

Delta (δ) Cephei, prototype of Cepheids, which has given its name to all similar variable stars, was discovered 230 years ago by the English astronomer John Goodricke. The Cepheids role as distance calibrators for more than a century means δ Cephei is one of the most studied stars, but astronomers were shocked to discover that they lacked an essential piece of information…