Category Astronomy/Space

Credit: ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble; NRAO/AUI/NSF

An ancient, red giant star in the throes of a frigid death has produced the coldest known object in the cosmos – the Boomerang Nebula. How this star was able to create an environment strikingly colder than the natural background temperature of deep space has been a compelling mystery for more than two decades. The answer, according to astronomers using ALMA may be that a small companion star has plunged into the heart of the red giant, ejecting most the matter of the larger star as an ultra-cold outflow of gas and dust.

This outflow is expanding so rapidly – about 10 times faster than a single star could produce on its own – that its temperature has fallen to less than 0.5 K (-458.5F)...

1.Artist illustration of star KELT-9 and its ultrahot planet KELT-9b. (Robert Hurt / NASA/JPL-Caltech)
2. KELT North telescope in Arizona. (KELT Collaboration)

Imagine a planet like Jupiter zipping around its host star every day and a half, superheated to temperatures hotter than most stars and sporting a giant, glowing gas tail like a comet. That is what an international research team led by astronomers at Ohio State and Vanderbilt universities think they have found orbiting a massive star they have labeled KELT-9, located 650 light years from Earth in the constellation Cygnus. With a day-side temperature peaking at 4,600 Kelvin, the newly discovered exoplanet, KELT-9b, is hotter than most stars and only 1,200 Kelvin cooler than our own sun...

This is a depiction of Mars today and what a warm and wet ancient Mars might have looked like. Credit: Wei Luo, Northern Illinois University

Findings suggest Mars had ocean, active hydrologic cycle. A new study led by Northern Illinois University geography professor Wei Luo calculates the amount of water needed to carve the ancient network of valleys on Mars and concludes the Red Planet’s surface was once much more watery than previously thought. The study bolsters the idea that Mars once had a warmer climate and active hydrologic cycle, with water evaporating from an ancient ocean, returning to the surface as rainfall and eroding the planet’s extensive network of valleys.

Satellites orbiting Mars and rovers on its surface have provided scientists with convincing evidence that water helped...

This shows a distant galaxy — visible as the smudge to the lower right — as it begins to align with and pass behind a star sitting nearer to us within the Milky Way. This is an event known as a transit. The star is called HD 107146, and it sits at the center of the frame. Its light has been blocked in this image to make its immediate surroundings and the faint galaxy visible — the position of the star is marked with a green circle.
Credit: ESA/Hubble & NASA

The NASA/ESA Hubble Space Telescope is famous for its jaw-dropping snapshots of the cosmos. The Picture of the Week is a distant galaxy – visible as the smudge to the lower right – as it begins to align with and pass behind a star sitting nearer to us within the Milky Way. This is an event known as a transit...