"The surface of the Earth is the shore of the cosmic ocean... Recently, we've managed to wade a little way out, and the water seems inviting." - Carl Sagan
What is a Hypernova?
Nova, “new star”; supernova, a “super” nova; hypernova, a super-duper, or super super, nova!
This word appeared in the astronomical literature at least as early as 1982, and refers to a kind of core-collapse supernova far brighter (>100 times) than usual; its meaning has changed somewhat, and today generally refers to the core collapse of particularly massive stars (>100 sols), whether or not they are spectacularly brighter than other core-collapse supernovae (though they are that too).
Most times you’ll come across hypernovae in material on gamma ray bursts (GRBs), many of which seem to involve emission of electromagnetic radiation with total energy many times that from ordinary supernovae (whether core collapse or Type Ia). Long-duration GRBs have jets, presumably from the poles of the temporary accretion disk which forms around the new black hole at the heart of the collapsed core of the progenitor (short-duration GRBs, which also produce jets, are thought to be the merger of two neutron stars, or a neutron star and a stellar-mass black hole), but even when viewed side-on (i.e. not looking into one of the jets), these GRBs are intrinsically much brighter than other core collapse supernovae.1
Eta Carinae (pictured below) is considered a good candidate for a future hypernova event.
Betelguese (pictured below) is another good candidate for a hypernova event.3
SN2007bi is the biggest such event observed to date.5
Rho Ophiuchi wide field
The clouds surrounding the star system Rho Ophiuchi compose one of the closest star forming regions. Rho Ophiuchi itself is a binary star system visible in the light-colored region on the image right. The star system, located only 400 light years away, is distinguished by its colorful surroundings, which include a red emission nebula and numerous light and dark brown dust lanes. Near the upper right of the Rho Ophiuchi molecular cloud system is the yellow star Antares, while a distant but coincidently-superposed globular cluster of stars, M4, is visible between Antares and the red emission nebula. Near the image bottom lies IC 4592, the Blue Horsehead nebula. The blue glow that surrounds the Blue Horsehead’s eye — and other stars around the image — is a reflection nebula composed of fine dust.
Image credit: Rogelio Bernal Andreo
Swirls and stars in IC 4678
Swirls of gas and dust enrich this little observed starfield toward the constellation of Sagittarius. Just to the side of the more often photographed Lagoon Nebula (M8) and the Trifid Nebula (M20) lies this busy patch of sky dubbed IC 4678. Prominent in the above image are large emission nebulas of red glowing gas highlighted by unusually bright red filaments. On the left, a band of thin dust preferentially reflects the blue light of a bright star creating a small reflection nebula. On the right and across the bottom, swaths of thicker dust appear as dark absorption nebulas, blocking the light from stars farther in the distance. IC 4678 spans about 25 light years and lies about 5,000 light years distant.
Image credit: Ken Siarkiewicz & Adam Block, NOAO, AURA, NSF
Earth from space: Kazakh treasure
This Kompsat-2 image was acquired over southwestern Kazakhstan’s Mangistau region east of the Caspian Sea.
Along the top of the image we can see water and wetlands, with eroded areas at the top and on the right. The majority of the image is dominated by flatland covered with low-lying vegetation.
The bright web of roads in the lower left section of the image is the Karakuduk oil field. Soviet geologists discovered oil there in the early 1970s, and commercial production began in the 1990s.
The white squares in this ‘web’ indicate where wells are located. We can also see buildings and other structures related to oil production.
Kazakhstan – and in particular, the Mangistau oblast – has large fossil fuel reserves and an abundant supply of other minerals and metals. Because of this, Mangistau is sometimes called the ‘treasure peninsula’ of Kazakhstan.
Image credit: KARI/ESA
Galaxies fed by funnels of fuel
Computer simulations of galaxies growing over billions of years have revealed a likely scenario for how they feed: a cosmic version of swirly straws.
The results show that cold gas — fuel for stars — spirals into the cores of galaxies along filaments, rapidly making its way to their “guts.” Once there, the gas is converted into new stars, and the galaxies bulk up in mass.
“Galaxy formation is really chaotic,” said Kyle Stewart, lead author of the new study appearing in the May 20th issue of the Astrophysical Journal. “It took us several hundred computer processors, over months of time, to simulate and learn more about how this process works.”
In the early universe, galaxies formed out of clumps of matter, connected by filaments in a giant cosmic web. Within the galaxies, nuggets of gas cooled and condensed, becoming dense enough to trigger the birth of stars. Our Milky Way spiral galaxy and its billions of stars took shape in this way.
Recent research has contradicted the former scenario in smaller galaxies, showing that the gas is not heated. An alternate “cold-mode” theory of galaxy formation was proposed instead, suggesting the cold gas might funnel along filaments into galaxy centers. Stewart and his colleagues set out to test this theory and address the mysteries about how the cold gas gets into galaxies, as well as the rate at which it spirals in.
Since it would take billions of years to watch a galaxy grow, the team simulated the process using supercomputers at JPL. The simulations began with the starting ingredients for galaxies — hydrogen, helium and dark matter — and then let the laws of physics take over to create their galactic masterpieces.
When the galaxy concoctions were ready, the researchers inspected the data, finding new clues about how cold gas sinks into the galaxy centers. The new results confirm that cold gas flows along filaments and show, for the first time, that the gas is spinning around faster than previously believed. The simulations also revealed that the gas is making its way down to the centers of galaxies more quickly than what occurs in the “hot-mode” of galaxy formation, in about 1 billion years.
The researchers looked at dark matter too — an invisible substance making up about 85 percent of matter in the universe. Galaxies form out of lumps of regular matter, so-called baryonic matter that is composed of atoms, and dark matter. The simulations showed that dark matter is also spinning at a faster rate along the filaments, spiraling into the galaxy centers.
Image credit: N-Body Shop at University of Washington
Working in space
High above planet Earth, a human helps an ailing machine. The machine, in this potentially touching story, is the Hubble Space Telescope, which is not in the picture. The human is Astronaut Steven L. Smith, and he is seen above retrieving a power tool from the handrail of the Remote Manipulator System before resuming work on HST in 1999 December. For most astronauts, space is not a place for relaxation and vacation, but rather a place for hard work. Since many space missions involve costly equipment and complicated experiments, astronauts are usually people of considerable knowledge and training. Although the hours may be long and work may be taxing, one frequently reported perk of working in space is the spectacular view.
Image credit: STS-103 Crew, NASA
Station and Shuttle transit the Sun
That’s no sunspot. On the upper right of the above image of the Sun, the dark patches are actually the International Space Station (ISS) and the Space Shuttle Atlantis on mission STS-132. In the past, many skygazers have spotted the space station and space shuttles as bright stars gliding through twilight skies, still glinting in the sunlight while orbiting about 350 kilometers above the Earth’s surface. But here, astrophotographer Thierry Lagault accurately computed the occurrence of a rarer opportunity to record the spacefaring combination moving quickly in silhouette across the solar disk. He snapped the above picture on last Sunday on May 16, about 50 minutes before the shuttle docked with the space station.
Image credit: Thierry Legault
In this composite image, visible-light observations by NASA’s Hubble Space Telescope are combined with infrared data from the ground-based Large Binocular Telescope in Arizona to assemble a dramatic view of the well-known Ring Nebula.
The Ring Nebula’s distinctive shape makes it a popular illustration for astronomy books. But new observations by NASA’s Hubble Space Telescope of the glowing gas shroud around an old, dying, sun-like star reveal a new twist.
Credit: NASA, ESA, C.R. Robert O’Dell (Vanderbilt University), G.J. Ferland (University of Kentucky), W.J. Henney and M. Peimbert (National Autonomous University of Mexico)
A magnetar called SGR 0418+5729 (SGR 0418 for short) has been shown to have the lowest surface magnetic field ever found for this type of neutron star.
This graphic shows an exotic object in our galaxy called SGR 0418+5729 (SGR 0418 for short). As described in our press release, SGR 0418 is a magnetar, a type of neutron star that has a relatively slow spin rate and generates occasional large blasts of X-rays.
The only plausible source for the energy emitted in these outbursts is the magnetic energy stored in the star. Most magnetars have extremely high magnetic fields on their surface that are ten to a thousand times stronger than for the average neutron star. New data shows that SGR 0418 doesn’t fit that pattern. It has a surface magnetic field similar to that of mainstream neutron stars.
In the image above, data from NASA’s Chandra X-ray Observatory shows SGR 0418 as a pink source in the middle. Optical data from the William Herschel telescope in La Palma and infrared data from NASA’s Spitzer Space Telescope are shown in red, green and blue.
Below, an artist’s impression showing a close-up view of SGR 0418. This illustration highlights the weak surface magnetic field of the magnetar, and the relatively strong, wound-up magnetic field lurking in the hotter interior of the star. The X-ray emission seen with Chandra comes from a small hot spot, not shown in the illustration. At the end of the outburst this spot has a radius of only about 160 meters, compared with a radius for the whole star of about 12 km.
Credit: X-ray: NASA/CXC/CSIC-IEEC/N.Rea et al; Optical: Isaac Newton Group of Telescopes, La Palma/WHT; Infrared: NASA/JPL-Caltech
— June 23, 2013
Be sure to look out for the Moon these next few months as it approaches Perigee, because the full moons during these times will appear exceptionally large. The Moon will be at its Perigee, or closest approach, in July 23 and it will reach full moon only a few minutes after it passes this point in its orbit.
These ‘super moons’ not only appear larger because they are physically closer but, combined with a full moon, the mind can play tricks on you to think they are much larger. This phenomena is called the Moon Illusion. Try to catch these full moons as they rise/set because the illusion works when there is an object in the foreground, like a tree, building or mountains.
From National Geographic Space Pictures This Week; May 17, 2013:
Star Factory T.A. Rector and H. Schweiker, WIYN/UAA/NOAO/NSF
Released this week, the image shows a region of the Taurus molecular cloud—about 450 light-years away from Earth. The nebula is full of stars in various stages of formation, from very new to old and established.
Forecast for Titan: Wild weather could be ahead
Saturn’s moon Titan might be in for some wild weather as it heads into its spring and summer, if two new models are correct. Scientists think that as the seasons change in Titan’s northern hemisphere, waves could ripple across the moon’s hydrocarbon seas, and hurricanes could begin to swirl over these areas, too. The model predicting waves tries to explain data from the moon obtained so far by NASA’s Cassini spacecraft. Both models help mission team members plan when and where to look for unusual atmospheric disturbances as Titan summer approaches.
“If you think being a weather forecaster on Earth is difficult, it can be even more challenging at Titan,” said Scott Edgington, Cassini’s deputy project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We know there are weather processes similar to Earth’s at work on this strange world, but differences arise due to the presence of unfamiliar liquids like methane. We can’t wait for Cassini to tell us whether our forecasts are right as it continues its tour through Titan spring into the start of northern summer.”
Titan’s north polar region, which is bejeweled with sprawling hydrocarbon seas and lakes, was dark when Cassini first arrived at the Saturn system in 2004. But sunlight has been creeping up Titan’s northern hemisphere since August 2009, when the sun’s light crossed the equatorial plane at equinox. Titan’s seasons take about seven Earth years to change. By 2017, the end of Cassini’s mission, Titan will be approaching northern solstice, the height of summer.
Given the wind-sculpted dunes Cassini has seen on Titan, scientists were baffled about why they hadn’t yet seen wind-driven waves on the lakes and seas. A team led by Alex Hayes, a member of Cassini’s radar team who is based at Cornell University, Ithaca, N.Y., set out to look for how much wind would be required to generate waves. Their new model, just published in the journal Icarus, improves upon previous ones by simultaneously accounting for Titan’s gravity; the viscosity and surface tension of the hydrocarbon liquid in the lakes; and the air-to-liquid density ratio.
The new model found that winds of 1 to 2 mph (2 to 3 kilometers per hour) are needed to generate waves on Titan lakes, a speed that has not yet been reached during Titan’s currently calm period. But as Titan’s northern hemisphere approaches spring and summer, other models predict the winds may increase to 2 mph (3 kilometers per hour) or faster. Depending on the composition of the lakes, winds of that speed could be enough to produce waves 0.5 foot (0.15 meter) high.
Image credit: NASA/JPL-Caltech/ASI/Cornell
Rare merger reveals secrets of galaxy evolution
A rare encounter between two gas-rich galaxies spotted by ESA’s Herschel space observatory indicates a solution to an outstanding problem: how did massive, passive galaxies form in the early Universe?
Most large galaxies fall into one of two major categories: spirals like our own Milky Way that are full of gas and actively forming stars, or gas-poor ellipticals, populated by old cool red stars and showing few signs of ongoing star formation.
It was long assumed that the large elliptical galaxies seen in the Universe today built up gradually over time via the gravitational acquisition of many small dwarf galaxies. The theory held that the gas in those galaxies would gradually be converted into cool, low-mass stars, so that by today they would have exhausted all of their star-forming material, leaving them ‘red and dead’.
So the discovery in the last decade that very massive elliptical galaxies had managed to form during just the first 3–4 billion years of the Universe’s history posed something of a conundrum. Somehow, on short cosmological timescales, these galaxies had rapidly assembled vast quantities of stars and then ‘switched off’.
One idea is that two spiral galaxies might collide and merge to produce a vast elliptical galaxy, with the collision triggering such a massive burst of star formation that it would rapidly deplete the gas reservoir. In a new study using Herschel data, astronomers have captured the onset of this process between two massive galaxies, seen when the Universe was just 3 billion years old.
The galaxy pair was initially identified in the Herschel data as a single bright source, named HXMM01. Follow-up observations showed that it is in fact two galaxies, each boasting a stellar mass equal to about 100 billion Suns and an equivalent amount of gas. The galaxies are linked by bridge of gas, indicating that they are merging.
“This monster system of interacting galaxies is the most efficient star-forming factory ever found in the Universe at a time when it was only 3 billion years old,” says Hai Fu from University of California, Irvine, USA, who led the study published in Nature.
“The HXMM01 system is unusual not only because of its high mass and intense star-forming activity, but also because it exposes a crucial, intermediate step of the merging process, providing valuable insight that will help us constrain models for the formation and evolution of galaxies,” adds co-author Asantha Cooray, also from University of California, Irvine.
The onset of the merger has sparked a star-formation frenzy, with the system spawning stars at a phenomenal rate equivalent to roughly 2000 stars like the Sun every year. By comparison, a galaxy like the Milky Way today only manages to produce the equivalent of one Sun-like star per year.
Image credit: ESA/NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO
Launching balloons to study space weather
In Antarctica in January, 2013 – the summer at the South Pole – scientists released 20 balloons, each eight stories tall, into the air to help answer an enduring space weather question: when the giant radiation belts surrounding Earth lose material, where do the extra particles actually go?
This NASA-funded mission is called BARREL, for Balloon Array for Radiation belt Relativistic Electron Losses. Each balloon launched by the BARREL team floated for anywhere from three to 40 days, measuring X-rays produced by fast-moving electrons high up in the atmosphere.
BARREL works hand in hand with another NASA mission called the Van Allen Probes, which travels directly through the Van Allen radiation belts. The belts wax and wane over time in response to incoming energy and material from the sun, sometimes intensifying the radiation through which satellites orbiting Earth must travel. Scientists need to understand this process better, and even provide forecasts of such space weather, in order to protect our spacecraft.
Image credit: NASA