Universe Today

December 11, 2019December 15, 2019 by Matt Williams

This Galaxy Has Been Home to 5 Supernovae in the Last 20 Years

Some of the most dramatic events in the Universe occur when certain stars die — and explode catastrophically in the process. Such explosions, known as supernovae, mainly occur in a couple of ways: either a massive star depletes its fuel at the end of its life, become dynamically unstable and unable to support its bulk, collapses inwards, and then violently explodes; or a white dwarf in an orbiting stellar couple syphons more mass off its companion than it is able to support, igniting runaway nuclear fusion in its core and beginning the supernova process. Both types result in an intensely bright object in the sky that can rival the light of a whole galaxy. In the last 20 years the galaxy NGC 5468, visible in this image, has hosted a number of observed supernovae of both the aforementioned types: SN 1999cp, SN 2002cr, SN2002ed, SN2005P, and SN2018dfg. Despite being just over 130 million light-years away, the orientation of the galaxy with respect to us makes it easier to spot these new ‘stars’ as they appear; we see NGC 5468 face on, meaning we can see the galaxy’s loose, open spiral pattern in beautiful detail in images such as this one from the NASA/ESA Hubble Space Telescope.

When stars die, they don’t die quietly but prefer to go out with a bang! This is known as a supernova, which occurs when a star has expended all of its fuel and undergoes gravitational collapse. In the process, the outer layers of the star will be blown off in a massive explosion visible from billions of light-years away. For decades, NASA has been monitoring galaxies beyond the Milky Way and detected numerous supernova taking place.

For instance, over the past 20 years, the Hubble Space Telescope has been monitoring the galaxy NGC 5468 – an intermediate spiral galaxy located roughly 130 million light-years from Earth in the constellation Virgo. In that time, this galaxy has experienced 5 supernovae and, thanks to its orientation (perpendicular to our own), astronomers have been able to study this galaxy and its supernovae in glorious detail.

December 11, 2019December 11, 2019 by Evan Gough

We Know We’re Made of Stardust. But Did it Come From Red Giants?

Artist's impression of a red giant star. If the star is in a binary pair, what happens to its sibling? Credit:NASA/ Walt Feimer

We’ve all heard this one: when you drink a glass of water, that water has already been through a bunch of other people’s digestive tracts. Maybe Attila the Hun’s or Vlad the Impaler’s; maybe even a Tyrannosaurus Rex’s.

Well, the same thing is true of stars and matter. All the matter we see around us here on Earth, even our own bodies, has gone through at least one cycle of stellar birth and death, maybe more. But which type of star?

That’s what a team of researchers at ETH Zurich (Ecole polytechnique federale de Zurich) wanted to know.

December 11, 2019January 1, 2020 by Susie Murph

Weekly Space Hangout: December 11, 2019 – Charlie Duke and Tom O’Conner from Astrograms

Hosts: Fraser Cain (universetoday.com / @fcain)

Dr. Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg & ChartYourWorld.org)

Dave Dickinson (www.astroguyz.com / @astroguyz)

Carolyn Collins Petersen (TheSpaceWriter.com / @spacewriter)

Moiya McTier (https://www.moiyamctier.com/ / @GoAstroMo)

December 10, 2019December 12, 2019 by Matt Williams

Why Does Enceladus Have Stripes at its South Pole?

Scientists recently determined that a certain strain of Earth bacteria could thrive under conditions found on Enceladus. Credit: NASA/JPL/Space Science Institute

Saturn’s moon Enceladus has captivating scientists ever since the Voyager 2 mission passed through the system in 1981. The mystery has only deepened since the arrival of the Cassini probe in 2004, which included the discovery of four parallel, linear fissures around the southern polar region. These features were nicknamed “Tiger Stripes” because of their appearance and the way they stand out from the rest of the surface.

Since their discovery, scientists have attempted to answer what these are and what created them in the first place. Thankfully, new research led by the Carnegie Institute of Science has revealed the physics governing these fissures. This includes how they are related to the moon’s plume activity, why they appear around Enceladus’ south pole, and why other bodies don’t have similar features.

December 10, 2019December 10, 2019 by Evan Gough

This is the Milky Way’s Magnetic Field

A representation of how our Galaxy would look in the sky if we could see magnetic fields. The plane of the Galaxy runs horizontally through the middle, and the Galactic centre direction is the middle of the map. Red–pink colours show increasing Galactic magnetic field strengths where the direction is pointing towards the Earth. Blue–purple colours show increasing Galactic magnetic field strengths where the direction is pointing away from the Earth. The background shows the signal reconstructed using sources outside our Galaxy. The points show the current measurements for pulsars. The squares show the measurements from this work using LOFAR pulsar observations. Image Credit: Sobey et al, 2019.

The Milky Way galaxy has its own magnetic field. It’s extremely weak compared to Earth’s; thousands of times weaker, in fact. But astronomers want to know more about it because of what it can tell us about star formation, cosmic rays, and a host of other astrophysical processes.

December 10, 2019December 10, 2019 by Evan Gough

NASA’s TESS Watched an Outburst from Comet 46P/Wirtanen

Comet 46P/Wirtanen. Image Credit: By Stub Mandrel at English Wikipedia, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=75160399

TESS, the Transiting Exoplanet Survey Satellite, has imaged an outburst from the comet 46P/Wirtanen. It caught the outburst in what NASA is calling the clearest images yet of a comet outburst from start to finish. A comet outburst is a significant but temporary increase in the comet’s activity, outside of the normal sunlight-driven vaporization of ices that creates a comet’s coma and tail.

Astronomers aren’t certain what causes them, but a new study based on this observation is shedding some light on them.

December 10, 2019December 10, 2019 by David Dickinson

December Meteor Squalls: Prospects for the 2019 Geminids and Ursids

December means chillier climes for northern hemisphere residents, a time to huddle inside near the campfire, both real and cyber. I’ve always thought this was a shame, as the cold crisp nights of winter also offer up sharp, clear skies. Over the past decade or so, December gives observers another reason to brave the cold: the Geminids.

December 10, 2019December 10, 2019 by Evan Gough

These Incredible Images of Alien Worlds are Actually Miniatures

View from an alien moon by Adam Makarenko. Image Copyright: Adam Makarenko

Have you heard of Adam Makarenko? No?

Adam is an artist who makes physical models of exoplanets then creates elaborate photo shoots of them. Adam is our new favorite Instagram feed at Universe Today, and he even took over the UT Instagram feed recently.

December 9, 2019December 9, 2019 by Nancy Atkinson

New Project Headed by Apollo’s Charlie Duke to Send Messages to Space

When astronaut Charlie Duke walked on the Moon in April of 1972 during the Apollo 16 mission, he brought along a very personal memento with a message he wanted to leave behind.

“When I walked on the Moon, I took a photo of my family along and wrote a brief message on the back of the photo to leave on the Moon,” Duke said. “I wanted my family to be part of my mission and it was my way of taking them with me – to celebrate my family.”

Duke has now helped spearhead a project that allows people on Earth to send their message into space. He says this project, called AstroGrams, enables anyone to celebrate, commemorate or communicate in space in a truly unique way.

December 9, 2019December 9, 2019 by Evan Gough

Why Are Particles Getting Ejected Off of Asteroid Bennu?

OSIRIS-REx discovered particles being ejected from asteroid Bennu shortly after arriving at the asteroid. Image Credit: NASA/Goddard/University of Arizona/Lockheed Martin

NASA’s OSIRIS-REx spacecraft arrived at asteroid Bennu in December 2018, and just one week later, it discovered something unusual about Bennu: the asteroid was ejecting particles into space.

The spacecraft’s navigation camera first spotted the particles, but scientists initially thought they were just stars in the background. After closer scrutiny, the OSIRIS-REx team realized they were particles of rock, and were concerned that they might pose a hazard.