Universe Today

February 9, 2009December 24, 2015 by Anne Minard

LCROSS Gets Set for Lunar Smash-Up

Artist's rendering of the Lunar Reconnaissance Orbiter and LCROSS at separation, courtesy of NASA

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Early next week, a NASA craft designed to hammer the moon will travel from California to the Kennedy Space Center — one step closer to the planned April 24 launch. The Lunar Crater Observation and Sensing Satellite, or LCROSS, will hitch a ride to the moon aboard the Lunar Reconnaissance Orbiter. The orbiter carries a suite of instruments for taking detailed temperature readings, looking at the effects of radiation on the lunar surface and scoping out good landing sites for future missions, among other science goals.

Sound a little intrusive? That’s nothing compared to the 15-foot (4.5-meter) deep, 100-foot (30 meter) wide hole that LCROSS will gouge into the lunar surface.

The whole package will spend about four days in transit to the moon, and then will orbit for several months, searching for the best impact site and setting up a prime trajectory. Around the first of August, LCROSS will approach the moon in two parts. First, it will fire its car-sized rocket to separate from the orbiter, then quickly shed the rocket and send it pummeling into the moon — at a whopping 5,600 miles (9,000 km) per hour. The target is the permanently shadowed floor in one of the North Pole’s craters, where ice is most likely to be hiding. The impact is expected to dislodge 220 tons of material from the lunar surface. Debris will fly as far as 30 miles (50 km) from the impact site, providing a Deep-Impact-style explosion that should be visible with amateur telescopes on Earth.

Then, the LCROSS satellite itself will fly through the plume on a collision course with the lunar surface, sending information to Earth until the moment of its own demise. The Lunar Reconnaissance Orbiter will be watching, along with India’s lunar orbiter, called Chandrayaan-1, Japan’s Kaguya (SELENE) and a host of Earth-bound professional telescopes. The sweet spot for observing the impact will be just after sunset in Hawaii, and possibly on the western coasts of the United States and South America — with countries along the moon’s course catching the aftermath.

Hints of water were sent to Earth in the 1990s, when the Naval Research Laboratory’s Clementine mission detected hydrogen signals at the lunar poles. The data did not reveal whether the element is contained in water or another hydrogen-bearing compound, such as hydrated minerals or hydrocarbons. LCROSS is the fourth mission to aim for the moon’s surface in the past decade. NASA’s 1999 impact with the Lunar Prospector failed to dislodge detectable water ice. The European Space Agency’s SMART-1 pummeled the lunar surface in 2006, while telecopes all over the world took data on the ejecta. India’s Moon Impact Probe detached from Chandrayaan-1 and crashed into the moon in October, with a goal of analyzing lunar dust and especially to find Helium 3, an isotope rare on Earth which could hold value for energy production. LCROSS will make the first definitive investigation for water within a permanently shadowed crater, the most likely place where it wouldn’t have evaporated over the moon’s history.

The $79 million, cost-capped mission is unusual because it utilizes commercially available technology for some of its software and scientific instruments. LCROSS could serve as a model for future missions that employ available technology, rather than relying on designs built from scratch, said Jonas Dino, a NASA spokesman at Ames Research Center in Moffett Field, California.

Finding water on the moon would boost its usefulness for supporting infrastructure. The moon could, for example, serve as a launching site for manned exploration of Mars or destinations beyond. The moon’s gravity, just one-sixth the strength of Earth’s, would allow the use of much smaller rockets to go the same distance as missions from Earth. Hydrogen from the lunar surface could also be used in making rocket fuel, which would cut costs for space exploration.

Sources: LCROSS website and interviews with NASA spokesmen Grey Hautaluoma, in Washington, D.C. and Jonas Dino in California.

February 9, 2009December 24, 2015 by Tammy Plotner

Australian Wildfire Update

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As Nancy reported on February 8th, the wild fires in Australia were not only serious, but out-of-control. While we had a look at satellite imagery, there’s nothing scarier than having it hit close to home and friends… Our friends at Southern Galactic.

As our Universe Today readers well know, our friends “down under” at Southern Galactic imaging are always on top the astronomy game, offering us up exclusive views of astronomy events not found any where else. Like the fire situation which raged in California last year, I watched remotely – curious as to how close it was getting to the observatories, but not knowing from a distance. I sat here in subzero weather watching the snow come down, while half a world away things were far, far different…

I had wondered why things were quiet. Skype was down and I wasn’t seeing a image on the remote scopes. My usual welcome “chat” with Bert was curiously absent, but the reality of what was going on didn’t sink in until now. I was complaining about plowing snow – but I should have been praying for my friends safety. When communications were re-established with Southerngalactic Site 1 telescope hosting facility this morning, Bert Candusio, the Observatory Director, told me about the wicked events which occurred on Saturday, February 7th… the day Victoria suffered under 47 degree Celsius heat with fires that tore through the state.

“We were awoken with radio warnings that a series of fires had taken hold and were running out of control. One fire in particular had caused us concern around 2:00 PM when the areas of Cobaw, Baynton and Pastoria were placed on alert that the fire had travelled 25 kilometers from the Northwest and was now headed towards the southeast in our direction.

Fires Approach Observatory - Bert Candusio

Within 2 hours, pillars of thick black smoke were seen to rise high in the air and began billowing to our northern horizon. We implemented our fire plan whereby all power and equipment were closed off after alerting our resident astronomers of the potential danger. With power supplies closed to the main observatory building, pumps were readied along with hoses, buckets of water as we had decided that the open grassed aspect of the property placed it with a good chance of surviving as long as we were able to mop up after the fire front had passed.

By 5:00 pm, the smoke has thickened to the point where it was actually creating its own weather systems at a local level, with thunder able to be heard high overhead such was the extent of the rising pillars above.

As we were gearing up for what could have been the worst, a sudden southerly wind change from the south began to drive the fire front to the north east and away from the site we were ready to defend. We were fortunate. Others were not.”

With the terrible conflagration passing within 8 kilometers of the Southern Galactic Telescope Hosting Facility, eating ash and breathing smoke clings to Candusio like the remnants of a horrible nightmare. Not only was his life’s work and investment sitting in the line of fire – but his home and loved ones as well. Only hours later, the fire which threatened the facility moved to the Hopetown area further north and is still out of control and the entire northeast and south section of Victoria still remains in danger. At the time of this writing, twelve separate fires continue to threaten lives, homes and property.

To Candusio, February 7 will live forever in his memory, but not as a good one. “To the surviving victims of that day’s terrible events, we extend our hearts and our deepest sympathies to them, their families and for their loved ones that have been lost.”

February 8, 2009December 24, 2015 by Fraser Cain

M Stars

Red Dwarf star and planet. Artists impression (NASA)

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Astronomers classify stars into groups according to their color and the presence of elements in the stars’ spectral signatures. This star classification system goes like this: O, B, A, F, G, K, M (here’s a way to remember them: “Oh be a fine girl, kiss me”.) M stars are coolest and most common stars in the Universe.

M stars range in temperature from 2,500 Kelvin and go all the way up to 3,500 Kelvin. They look red to our eyes. M stars account for 75% of the stars in our stellar neighborhood, so they’re the most common by far! Most M stars are tiny red dwarfs, with less than 50% of the mass of the Sun, but some are actually giants and supergiants, like the red giant Betelgeuse.

Some familiar M stars include Betalgeuse (red giant), and the red dwarfs Proxima Centauri, Barnard’s star, and Gliese 581

We have written many articles about stars here on Universe Today. Here’s an article about how red dwarf stars have small habitable zones.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

February 8, 2009December 24, 2015 by Fraser Cain

K Stars

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To organize all the stars in the Universe, Astronomers use a classification system that collects the stars into groups based on their color and the presence of various elements in the star’s outer atmosphere. So, here are the classifications: O, B, A, F, G, K, M (if you need to remember then, just keep this in mind: “Oh be a fine girl, kiss me”.) K stars are cooler than the Sun.

K stars start at about 3,500 Kelvin, and can get as hot as 5,000 Kelvin. This makes them look orange-red to our eyes. K stars can actually vary in size from main sequence stars with less mass than the Sun to red giants and supergiants with many times the mass of the Sun. It’s all because of the temperature. They have weak hydrogen lines and mostly neutral metals, like Manganese, Iron and Silicon. About 13% of stars in the stellar neighborhood are K stars.

Some familiar K stars include Alpha Centauri B, Epsilon Eridani, Arcturus, Aldebaran

We have written many articles about stars here on Universe Today. Here’s an article about the closest known star with extrasolar planets, Epsilon Eridani.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

February 8, 2009December 24, 2015 by Fraser Cain

G Stars

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Astronomers collect the stars in the Universe into a classification system that organized them by color and spectral signature (the presence of various metals in the star’s outer atmosphere). Here are the classifications: O, B, A, F, G, K, M (if you need to remember then, just keep this in mind: “Oh be a fine girl, kiss me”.) G stars are perhaps the best known stars out there. That’s because our own Sun is a G star.

G stars range in temperature from 5,000 Kelvin to 6,000 Kelvin, and they appear white or yellow-white to our eyes. You can also recognize a G star by the presence of Calcium in their spectral signature, but with weaker hydrogen lines than F type stars. G stars represent 7.7% of all the stars in our stellar neighbourhood.

Some familiar G stars include The Sun, Alpha Centauri A, Capella, Tau Ceti

We have written many articles about stars here on Universe Today. Here’s an article about the search for planets around Alpha Centauri.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

February 8, 2009December 24, 2015 by Fraser Cain

F Stars

Astronomers classify the stars out there into groups based on the color of the star and the presence of certain elements in the star’s atmosphere. The classifications are: O, B, A, F, G, K, M (just remember this handy mnemonic , “Oh be a fine girl, kiss me”.) F stars are still hotter than the Sun, appearing white to our eyes.

F stars have a surface temperature of 6,000 Kelvin to 7,200 Kelvin. You can also recognize an F star by the presence of Calcium in their spectral signature, as well as neutral metals like Iron and Chromium. F stars represent 3.1% of all stars.

Some familiar F stars include Arrakis, Canopus, Procyon.

We have written many articles about stars here on Universe Today. Here’s an article about some strange observations of Procyon.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

February 8, 2009December 24, 2015 by Fraser Cain

A Stars

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Astronomers have developed a star classification system to organize all the stars we can see in the Universe; it’s based on color and the spectral signature of certain elements in the star’s atmosphere. The classifications are: O, B, A, F, G, K, M (here’s a handy mnemonic , “Oh be a fine girl, kiss me”.) A stars are some of the more common stars seen with the unaided eye: they appear white or bluish-white.

The surface temperatures of A stars range from 7,400 Kelvin to 10,000 Kelvin; that’s about twice the temperature of the Sun, so these stars are really hot. Astronomers also recognize them by the strong hydrogen lines, as well as lines of ionized metals, like Iron, Magnesium and Silicon. A stars are more massive than the Sun, but don’t lead lives that are too much different than the life of our own Sun.

Some familiar A stars include Vega, Sirius, and Deneb.

We have written many articles about stars here on Universe Today. Here’s an article about how Vega has a cool, dark equator, and it might even have planets.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

February 8, 2009December 24, 2015 by Fraser Cain

O Stars

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Astronomers have developed a method of classifying stars based on their color and some other characteristics. The star classifications are O, B, A, F, G, K, M (you can remember that with the handy mnemonic, “Oh be a fine girl, kiss me”.) O stars are the most extreme group of all. They have the highest temperatures, the most luminosity, and the most mass (oh, and the shortest lives).

An O star appears blue to the eye, and can have a surface temperature of more than 41,000 Kelvin; its color would be better described as ultraviolet, but we can’t see that color with our eyes. The surface temperature of an O star is so great that hydrogen on the surface of the star is completely ionized, but other elements are more visible, like Helium, Oxygen, Nitrogen, and Silicon.

O stars are very massive and evolve very rapidly. Shortly after they form as a protostar, they already have the pressure and temperatures in their cores to begin hydrogen burning. The O stars light up their stellar nurseries with ultraviolet light and cause the clouds of nebula to glow. You can thank O stars for illuminating the beautiful nebula photographs captured by Hubble. O stars burn through their fuel quickly, and can detonate as supernovae in just a few million years.

Some O stars include Zeta Orionis, Zeta Puppis, Lambda Orionis, Delta Orionis.

We have written many articles about stars here on Universe Today. Here’s an article about an O star.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

February 8, 2009December 24, 2015 by Fraser Cain

Star Evolution

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Although they’re just hot balls of hydrogen and helium, stars are constantly changing over time. Studying star evolution is a whole branch of astronomy, and scientists are learning new things all the time.

To really understand star evolution, you’ve got to go right back to the beginning. All the stars we see today started out as large clouds of cold molecular hydrogen. Some event, like a nearby supernova, passed through the cloud of gas and gave it the kick it needed to begin collapsing. The gravity of the cloud pulled unevenly, and so it tore into smaller clouds, each of which would go on to form a new star.

In one cloud, the material streamed together to form a growing ball of hydrogen and helium. This protostar was enshrouded in gas and dust, and would actually be invisible from our Earth-based telescopes. As the ball grew, more and more material came in, causing the protostar to spin, and releasing jets of material from its poles. This accumulation of material takes about 100,000 years.

Once all the material was accumulated, the pre-star was hot and glowing; almost like a real star. But it wasn’t heated by fusion reactions in its core, but through the gravitational energy of the continuously collapsing material. This hot, young object is known as a T Tauri star, and remains in this state for about 100 million years.

Finally the temperature and pressure at the core of the star were sufficient to allow nuclear fusion to get going. Now the star would become a true main sequence star, converting hydrogen into helium at its core. A star with the mass of our Sun could stay in the main sequence stage for more than 12 billion years. More massive stars will last for shorter periods of time, while the tiny red dwarf stars can last for hundreds of billions and even trillions of years.

Eventually the star runs out of hydrogen fuel in its core. Without the outward light pressure from the fusion reactions, the star starts to contract, creating more temperature and pressure in the core. A shell of hydrogen around the core can now undergo nuclear fusion, and so it does, increasing the star’s brightness hundreds and even thousands of times. And in the core of the star, helium is fused into even heavier elements. This causes the star to bloat out to become a red giant. Regular stars like our Sun will expand to the point that they consume the interior planets: Mercury, Venus and even Earth. Stars with more than 20 times the mass of the Sun become red supergiants, expanding out more than 1500 times the radius of the Sun. Imagine a star so big it consumed the orbit of Saturn!

This extra fuel runs out and so the star collapses down on itself again. More massive stars will be able to do this trick multiple times, burning new shells and burning heavier and heavier elements. Eventually all stars reach their limit. The most massive stars, those with more than 20 times the mass of the Sun, will detonate as supernovae. Less massive stars will eject their outer layers and then collapse inward forming a white dwarf, neutron star or black hole. Our Sun will form a white dwarf; a remnant the size of the Earth with 60% of its original mass. Although initially hot, this white dwarf will slowly cool down over time, eventually becoming the background temperature of the Universe.

And that’s star evolution, from cloud of gas to white dwarf.

We have written many articles about stars here on Universe Today. Here’s an article about a supercomputer simulating star evolution, and here’s an article that explains what happens to the Earth when the Sun becomes a red giant.

If you’d like more information on stars, check out Hubblesite’s News Releases about Stars, and here’s the stars and galaxies homepage.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

Reference:
NASA: The Life Cycles of Stars

February 8, 2009December 24, 2015 by Tammy Plotner

Look Into the Cat’s Eye…

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Are you ready for more stereo vision? This haunting Hubble Telescope image has been visualized for dimension by the one and only Jukka Metsavainio and gives us a look at one of the most complex planetary nebulae ever photographed. Inside NGC 6543 – nicknamed the “Cat’s Eye Nebula” – the Hubble has revealed delicate structures including concentric gas shells, jets of high-speed gas, and unusual shock-induced knots of gas… and thanks to Jukka’s “magic vision” we’re able to take a look into the Cat’s Eye as it might appear in dimension. Step inside and let’s learn more…

When Jukka produces an image, it’s more than just a clever Photoshop “trick”. Hours of study must go into each image, because the light is acting differently in each part of the nebula. To make these images work correctly, Jukka must understand which stars are causing the ionization, which stars are nearer and further from our point of perspective and so on. Each type of image is totally unique and what makes dimension work for a reflection nebula won’t work for an emission nebula. Says Jukka; “To be able to make those stereo pairs, one have to learn lots of things about the targets, and beside that, study the actual image more deeply than usual. Star distances must be measured by the size and the color. For example, stars with yellowish hue must be in or behind the nebulosity, white/blue ones are front of it.”

Because dimension will appear reversed by the method you choose to use to view these images, Jukka makes two versions. The first you see at the top of the page is parallel vision – where you relax your eyes and when you are a certain distance from the monitor screen the two images will merge into one to produce a 3D version. The second – which appears below – is crossed vision. This is for those who have better success crossing their eyes to form a third, central image where the dimensional effect occurs. So, now that you understand the images are a visualization and how they are created, let’s take a parallel look…

And now it’s my turn to add a little “magic” to what you see.

Estimated to be 1,000 years old, the Cat’s Eye is a portrait of a dying star – and quite possibly an unresolved double-star system. According to research, the dynamical effects of two stars orbiting one could very well be the cause of the complicated and intricate structures revealed here – structures normally not seen in planetary nebulae. When NGC 6543 was first observed spectroscopically, it showed the presence of emission lines, an indicator of multiple stars, but also an indictor of diffuse gas clouds.

As studies progressed, more hypothesis about the NGC 6543’s structure began to emerge. Perhaps a fast stellar wind from the central star created the elongated shell… It could be the companion star is emitting high-speed jets of gas that lie at right angles to the equatorial ring… Maybe the stellar wind has carved out the inner structure of the nebula are there are more than one there? Says L.F. Miranda; “The velocity field of NGC 6543 shows the existence of two concentric ellipsoidal shells in the nebula. The two shells likely represent the inner and outer surface layers of a geometrically ‘Thick Ellipsoid’ (TE) which constitutes the basic structure of NGC 6543.”

Even more research ensued, and with it came the twin jet theory and the ejection of materials spaced over intervals of time – like cosmic smoke rings being puffed off at perfect intervals. According to Bruce Balik; “Hubble archival images of NGC 6543 reveal a series of at least nine regularly spaced concentric circular rings that surround the famous nebular core, known as the Cat’s Eye Nebula. The rings are almost certainly spherical bubbles of periodic isotropic nuclear mass pulsations that preceded the formation of the core. Their ejection period is consistent with a suggestion that quasi-periodic shells are launched every few hundred years in dust-forming asymptotic giant branch (AGB) winds but not consonant with the predictions of extant models of core thermal pulses (~105 yr) and surface pulsations (~10 yr).”

To be sure, there are simply a lot of things that we don’t know or understand about the Cat’s Eye Nebula just yet. It is possible that magnetic activity somewhat similar to our own Sun’s sunspot cycle, could be at work here. Says Dr. Balick; “What do the rings imply? Since they’re larger than the bright cores of the nebulae that they surround, the rings are almost certainly material ejected episodically before the main and bright core of the nebula formed. This means that the start that ejected the nebulae first quivered and shivered and made these concentric rings. Then something big happened, and the density and mechanism for ejecting the mass changed abruptly. This is when the core of the nebula was formed, typically between 1000 and 2000 years ago. The rhythmic ringing of a dying star is expected as the last of its nuclear fuel is suddenly triggered into ignition by the increasing crush of gravity — much like the juice ejected by squeezing an orange with increasing force. Each expulsion of juice temporarily relieves the internal pressure inside the orange. Similarly, each ejection of mass temporarily stops the combustion of the final dregs of the star’s remaining fuel. Why should the pattern of ejection mass change so radically and strongly? We can only conjecture. Its possible that an orbiting star or giant planet falls onto the dying star. It hits the surface with such force that its atoms ignite in a large conflagration. Somehow, the burst of heat drives the remnants of the dying star into space in fantastic patterns.”

And we looked right into its eye…

My many thanks once again to Jukka Metsavainio of Northern Galactic for his artistry and we look forward to the next installment!