Two Stars On A Death Spiral Set To Detonate As A Supernova

Two white dwarfs circle around one other, locked in a fatal tango. With an intimate orbit and a hefty combined mass, the pair is ultimately destined to collide, merge, and erupt in a titanic explosion: a Type Ia supernova.

Or so goes the theory behind the infamous “standard candles” of cosmology.

Now, in a paper published in today’s issue of Nature, a team of astronomers have announced observational support for such an arrangement – two massive white dwarf stars that appear to be on track for a very explosive demise.

The astronomers were originally studying variations in planetary nebulae, the glowing clouds of gas that red giant stars throw off as they fizzle into white dwarfs. One of their targets was the planetary nebula Henize 2-428, an oddly lopsided specimen that, the team believed, owed its shape to the existence of two central stars, rather than one. After observing the nebula with the ESO’s Very Large Telescope, the astronomers concluded that they were correct – Henize 2-428 did, in fact, have a binary star system at its heart.

This image of the unusual planetary nebula was obtained using ESO’s Very Large Telescope at the Paranal Observatory in Chile. In the heart of this colourful nebula lies a unique object consisting of two white dwarf stars, each with a mass a little less than that of the Sun. These stars are expected to slowly draw closer to each other and merge in around 700 million years. This event will create a dazzling supernova of Type Ia and destroy both stars. Credit: ESO
This image of the unusual planetary nebula was obtained using ESO’s Very Large Telescope at the Paranal Observatory in Chile. In the heart of this colourful nebula lies a unique object consisting of two white dwarf stars, each with a mass a little less than that of the Sun. These stars are expected to slowly draw closer to each other and merge in around 700 million years. This event will create a dazzling supernova of Type Ia and destroy both stars. Credit: ESO

“Further observations made with telescopes in the Canary Islands allowed us to determine the orbit of the two stars and deduce both the masses of the two stars and their separation,” said Romano Corradi, a member of the team.

And that is where things get juicy.

In fact, the two stars are whipping around each other once every 4.2 hours, implying a narrow separation that is shrinking with each orbit. Moreover, the system has a combined heft of 1.76 solar masses – larger, by any count, than the restrictive Chandrasekhar limit, the maximum ~1.4 solar masses that a white dwarf can withstand before it detonates. Based on the team’s calculations, Henize 2-428 is likely to be the site of a type Ia supernova within the next 700 million years.

“Until now, the formation of supernovae Type Ia by the merging of two white dwarfs was purely theoretical,” explained David Jones, another of the paper’s coauthors. “The pair of stars in Henize 2-428 is the real thing!”

Check out this simulation, courtesy of the ESO, for a closer look at the fate of the dynamic duo:

 

Astronomers should be able to use the stars of Henize 2-428 to test and refine their models of type Ia supernovae – essential tools that, as lead author Miguel Santander-García emphasized, “are widely used to measure astronomical distances and were key to the discovery that the expansion of the Universe is accelerating due to dark energy.” This system may also enhance scientists’ understanding of the precursors of other irregular planetary nebulae and supernova remnants.

The team’s work was published in the February 9 issue of Nature. A copy of the paper is available here.

What Is This Empty Hole In Space?

What may appear at first glance to be an eerie, empty void in an otherwise star-filled scene is really a cloud of cold, dark dust and molecular gas, so dense and opaque that it obscures the distant stars that lie beyond it from our point of view.

Similar to the more well-known Barnard 68, “dark nebula” LDN 483 is seen above in an image taken by the MPG/ESO 2.2-meter telescope’s Wide Field Imager at the La Silla Observatory in Chile.

While it might seem like a cosmic no-man’s-land, no stars were harmed in the making of this image – on the contrary, dark nebulae like LDN 483 are veritable maternity wards for stars. As their cold gas and dust contracts and collapses new stars form inside them, remaining cool until they build up enough density and gravity to ignite fusion within their cores. Then, shining brightly, the young stars will gradually blast away the remaining material with their outpouring wind and radiation to reveal themselves to the galaxy.

The process may take several million years, but that’s just a brief flash in the age of the Universe. Until then, gestating stars within LDN 483 and many other clouds like it remain dim and hidden but keep growing strong.

Wide-field view of the LDN 483 region. (Credit: ESO and Digitized Sky Survey 2)
Wide-field view of the LDN 483 region. (Credit: ESO and Digitized Sky Survey 2)

Located fairly nearby, LDN 483 is about 700 light-years away from Earth in the constellation Serpens.

Source: ESO

Weekly Space Hangout – Jan 9, 2015: Andy Weir of “The Martian”

Host: Fraser Cain (@fcain)
Special Guest: Andy Weir , author of “The Martian”
Andy was first hired as a programmer for a national laboratory at age fifteen and has been working as a software engineer ever since. He is also a lifelong space nerd and a devoted hobbyist of subjects like relativistic physics, orbital mechanics, and the history of manned spaceflight. “The Martian” is his first novel.

Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Ramin Skibba (@raminskibba)
Brian Koberlein (@briankoberlein)
Dave Dickinson (@astroguyz / www.astroguyz.com)
Nicole Gugliucci (cosmoquest.org / @noisyastronomer)
Continue reading “Weekly Space Hangout – Jan 9, 2015: Andy Weir of “The Martian””

Famous Hubble Star Explosion Is Expanding, New Animation Reveals

Wow! One of the most famous star explosions captured by the Hubble Space Telescope — several times — shows clear evidence of expansion in this new animation. You can see here the Homunculus Nebula getting bigger and bigger between 1995 and 2008, when Hubble took pictures of the Eta Carinae star system. More details from one of the animation authors below.

“I had the idea to check the Hubble image of Eta Carinae because I know this star rather well,” wrote Philippe Henarejos, one of the authors of the animation, in an e-mail to Universe Today. Henarejos has written several times about the star for the magazine he edits, Ciel et espace (Sky and Space) and also published a French-language book on star histories.

“Telling this story, I realized that astronomers knew for a long time that the Homunculus Nebula was expanding. Also, I knew that the HST had taken many photos of this object since 1995. So I thought that thanks to the very high resolution of the HST images, it could be possible to see the expansion.”

Eta Carinae from Hubble's STIS instrument. Credit: NASA, ESA, and the Hubble SM4 ERO Team
Eta Carinae from Hubble’s STIS instrument. Credit: NASA, ESA, and the Hubble SM4 ERO Team

Along with colleague Jean-Luc Dauvergne, Henarejos tracked down two images in the archives and searched for a fixed object that wouldn’t be moving as the expansion occurred, which they decided would be two stars close to the border of the field of view. Then Dauvergne found a third image that clearly showed the expansion happening.

The two gentlemen then verified their findings with astronomer John Martin from the University of Illinois, who maintains a page on Eta Carinae. “He told me that the expansion is real,” Henarejos said.

And the animation is already getting attention. After being published in the new magazine First Light, it was featured today on the Astronomy Picture of the Day website.

Eta Carinae mysteriously brightened about 170 years ago, becoming the second-most luminous object in Earth’s night sky. Then it faded 150 years ago. Astronomers are still examining the system to see what might have caused this.

This Dark Nebula Looks Like it is Writhing in Agony

We’ve got at least one scary night ahead with Halloween falling on Friday. Adam Block, manager at the Mount Lemmon SkyCenter at the University of Arizona sent us this image of the nebula LBN 438, explaining that this dark cloud of dust glows eerily both from scattered starlight and extended red emission due to the radiation of a nearby star.

“My mind alternates between something dancing in ecstasy or writhing in torture,” Adam said. “Either way, very spooky…”

Adam just happens to have access to a 32-inch Schulman Telescope (RCOS) at Mt Lemmon, and used a SBIG STX16803 CCD Camera to get this scary shot. Find out more about this image here.

Carnival of Space #357

Carnival of Space. Image by Jason Major.

Welcome, come in to the 357th Carnival of Space! The carnival is a community of space science and astronomy writers and bloggers, who submit their best work each week for your benefit. I’m Susie Murph, part of the team at Universe Today and now, on to this week’s stories!

We’re going to start off with a double blast from the past, courtesy of CosmoQuest! This week, they’re featuring Stuart Robbins’s blog post from January 13, 2012, titled “Perspective on the Apollo 15 Landing Site.” He explores the region of the Moon that is the current home of the MoonMappers images that YOU are still mapping and exploring today – the Apollo 15 landing site area. It’s a neat place and we can study a lot of things there. Due to a quirk of optics and angles, you can even imagine you’re flying towards it.

Next, we stay with Cosmoquest’s Moon Mappers as they highlight the interesting discovery that the groundbreaking Soviet Lunakhod 2 lunar rover traveled farther than earlier estimated on it’s mission in 1972. Visit MoonMappers at Cosmoquest for more great stories!

Moving through history, we travel over to io9’s Space blog for a history of the American Space Shuttle disasters is a grim reminder of the danger of space travel. Just released is Major Malfunction, a documentary on the two Shuttle catastrophes. Major malfunction is an understatement for the destruction of Space Shuttle Challenger moments after launch in 1986, and the loss of Space Shuttle Columbia during re-entry in 2003.

Next at io9, we visit Mars to view the magnificent Draa, which are ancient landforms created from waves of sand. Check out the article and it’s images here.

We also have another article from io9, which new astronaut Reid Wiseman recounts his first adventurous days in space.

Now we’ll jump over for some gorgeous views from the Chandra X-Ray Observatory! One of their new images is a glorious view of the Whirlpool spiral galaxy which radiates with fantastic points of x-ray light. These image is breath-taking!

Want more gorgeous images? Visit Brownspaceman.com to see his discussion of the Tulip Nebula, which is a composite image which also maps the emissions from this incredible nebula.

Next, we head over to the Meridani Journalfor coverage of a major find in the search for exoplanets. A new world which is more than twice as large as Earth and about 17 times heavier has been discovered, a sort of “mega-Earth” as some have referred to it.

The NextBigFuture Blog lives up to it’s name by bringing us two interesting stories from Elon Musk and his company SpaceX. First, he points out that the key is reusability. Musk said the crewed Dragon is designed to land softly back on Earth and be rapidly turned around for another flight — possibly on the same day. Spacex is aiming for 10 flights without any significant refurbishment for the Dragon v2. The thing that will have to be refurbished is the main heat shield. Further improved heat shield materials [later versions of PICA-X] would mean Spacex could aim for 100 reusable flights.

We then head over to the Urban Astronomer, where recent observations of a very near pair of brown dwarf objects has led to something new: We’re watching the weather on stars themselves!

Finally, we return to Universe Today for some interesting potential missions. First, the B612 Foundation’s privately-funded Sentinel mission, once launched and placed in orbit around the Sun in 2018, will hunt for near-Earth asteroids down to about 140 meters in size using the most advanced infrared imaging technology, without government red tape to hamper the mission. Next, the NASA Innovative Advanced Concepts office announced a dozen far-flung drawing-board proposals that have received $100,000 in Phase 1 funding for the next 9-12 months, one of which is a balloon for exploring Titan. We’re looking forward to hearing about these projects and many others in the coming years.

That’s it for this week’s Carnival! See you all next time!

And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.

Stunning 3D Tours of Two Well-Known Nebulae

Two videos recently released by the Hubble team take us on a tour of two famous and intriguing cosmic objects: the stellar wind-blown “celestial snow angel” Sharpless 2-106 and the uncannily equine Horsehead Nebula, imaged in infrared wavelengths by the HST.

Using Hubble imagery complemented with data from the Subaru Infrared Telescope and ESO’s Visible and Infrared Survey Telescope for Astronomy — VISTA, for short — the videos show us an approximation of the three-dimensional structures of these objects relative to the stars surrounding them, providing a perspective otherwise impossible from our viewpoint on Earth.

The stellar nursery Sharpless 2-106 is above; hop on the Horsehead Nebula tour below:
Continue reading “Stunning 3D Tours of Two Well-Known Nebulae”

Hubble Captures Starbirth In A Monkey’s Head As Telescope Approaches 24 Years In Space

Billowing gas clouds and young stars feature in this February Hubble Space Telescope image, released as the telescope approaches its 24th birthday this coming April. The telescope has seen a lot of drama over the years, but in this case, thankfully the excitement is taking place 6,400 light-years away. Here you can see starbirth in action in the nebula NGC 2174, which is sometimes called the Monkey Head Nebula.

“This region is filled with young stars embedded within bright wisps of cosmic gas and dust. Dark dust clouds billow outwards, framed against a background of bright blue gas. These striking hues were formed by combining several Hubble images taken through different coloured filters, revealing a broad range of colours not normally visible to our eyes,” the European Space Agency wrote.

“These vivid clouds are actually a violent stellar nursery packed with the ingredients needed for building stars. The recipe for cooking up new stars is quite inefficient, and most of the ingredients are wasted as the cloud of gas and dust disperses. This process is accelerated by the presence of fiercely hot young stars, which triggers high-speed winds that help to blow the gas outwards.”

Hubble’s dramatic history includes a deformed mirror, a rescue mission, and a nearly last-minute decision to do a shuttle flight for repairs and upgrades when the shuttle program was wrapping up. You can read more about Hubble’s colorful history at the Space Telescope Science Institute.

And Hubble has captured this nebula before, as you can see in this 2011 release.

Sources: ESA and Space Telescope Science Institute

Astrophoto: The Red Rectangle in Space

Due to gravity, most objects in space are spherical — whether it’s round planets and stars or swirling spiral galaxies. That’s why this object, the Red Rectangle Nebula, or HD 44179, is so intriguing.

“The overall shape of the nebula is a puzzle for astronomers to figure out,” said astronomer Adam Block from the Mount Lemmon SkyCenter at the University of Arizona, via email. “The leading theory suggests that bipolar, cone-shaped, and periodic outflows, when viewed in profile as we do, may give the shape we see. The intense red color still remains a bit of a mystery.”

From most “smaller” ground based telescopes, this object really does look like a rectangle, but images from space, such as from the Hubble Space Telescope, reveal that rather than being rectangular, is shaped like an X with additional complex structures of spaced lines of glowing gas, a little like the rungs of a ladder. This stunning new image from Adam also captures these features.

He said he wanted to know what it really looked like from a ground-based telescope using full color (broad band) filters.

“I didn’t know, but now I do,” Adam said. “It is a tiny tiny thing; but it was wonderful to see it develop from the raw data to this rendered result. The central star is very bright and nearly overwhelms the interesting parts of the nebula. In addition to its size, the central star is a big challenge to tame.”

See a larger version and find out more of the observing details here.