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Exciting news from the heavens!  Today NASA has reported that the Kepler mission has discovered 3 new planets in the habitable zones of two distant stars.  Of the thousands of worlds so far discovered, these three are most likely to be habitable.  Best of all the planets are crazy!

Kepler is a NASA space telescope which was launched on March, 2009.  It makes use of an incredibly sensitive photometer to simultaneously & incessantly monitor the brightness of over 150,000 nearby stars.  The brightness of a star dims slightly whenever an exoplanet transits between it and Kepler.  Thanks to Kepler’s inhuman vigilance and robotic ability to perceive nearly imperceptible light changes, we are now discovering thousands of new planets, although most of them are Jovian sized gas worlds.

Kepler Space Telescope

Kepler Space Telescope

The three worlds reported today lie in the habitable zone—the region around a star where water exists in a liquid form (as it does here on beautiful Earth).  Two of the newly discovered habitable zone planets are in a five planet system orbiting a dwarf star just two-thirds the size of the sun which lies 1,200 light years from Earth.   Here is a diagram of the Kepler 62 system.

Kepler 62 System (Art by NASA)

Kepler 62 System (Art by NASA)

Of these five worlds, two lie in the habitable zone, Kepler 62f and Kepler 62e.  Kepler 62 F is most likely a rocky planet and is only 40 percent larger than Earth.  It has an orbit which last 267 (Earth) days.  So far it is the smallest exoplanet found in the habitable zone.  The star it orbits is 7 billion years old (as opposed to the sun which is four and a half billion years old) so life would have had plenty of time to develop.  The other habitable zone planet in the Kepler 62 system, Kepler 62e is probably about 60% larger than our planet.   It is somewhat closer to the star and astrophysicists speculate it may be a water world of deep oceans.

No! Not that sort of Waterworld!

No! Not that sort of Waterworld!

The other new exoplanet Kepler-69c appears to orbit a star very similar to Earth’s sun.  It orbits at the inward edge of the habitable zone (nearing where Venus is in our solar system) so it may be hot.  The planet is estimated to be about 70% larger than Earth, and is also thought to be a water world with oceans thousands of kilometers deep.  I am finding it impossible not to imagine those vast oceans filled with asbestos shelled sea-turtles the size of dump trucks, huge shoals of thermophile micro-squid, and burning-hot chartreuse uber-penguins, but if any life is actually on Kepler-69c, it is probably extremely different from Earth life.

I understand why they are green and have gills, but why are they inside gelatin capsules? (DC Comics)

I understand why they are green and have gills, but why are they inside gelatin capsules? (DC Comics)

Of course Kepler can only find these planets; it is unable to observe very much about them.  In order to do that, humankind will need some sort of huge amazing super telescope.  Speaking of which, tune in next week when I write about humankind’s plans for building a huge amazing super telescope in the Chilean Andes!

Mind-blowing diagram comparing Vancouver to a Neutron Star (by Christian Joore)

Most items in the heavens are inconceivably large.  The sun, a fairly ordinary star has a diameter of 1,391,000 kilometers (864,327 miles).  Even a tiny planetoid like the moon has a diameter of 3,474 km (2,159 miles).  However a few noteworthy items in the heavens are so small that we can think of them in human terms—like neutron stars, which are the size of a town or small city with a diameter of only 20 or 30 kilometers (about ten to 15 miles  miles).   But even though they are the size of a small asteroid or Manhattan Island, neutron stars are hardly inconsequential.  These dinky stars can have more mass than the entire glorious sun (which itself is 332,946 times more massive than the Earth and everything on it).  A 1.27 cubic centimeter block of such material (approximately the size of a half an inch sugar cube) would weigh approximately the same as all of the human inhabitants of Earth (give or take).

Neutron stars are left-over fragments of supernovae explosions.  When a star 4 to 8 times more massive than our sun burns through all available fuel, its outer layers blow apart in a supernova which spreads glittering matter across great swaths of space.  The dense remaining portion of the stellar core undergoes a titanic battle between electron degeneracy pressure and gravity.  If the fragment has more than 1.44 stellar masses, gravity wins and the electrons and protons of its constituent matter are crushed into super dense neutrons.  Such explosions are tremendously dynamic and bright.  In 1054 AD, Sung dynasty astronomers recorded such an explosion which outshone the moon.  Contemporary astronomers have determined that the 1054 AD supernova created the Crab Nebula, an oval shaped mass of hydrogen, carbon, oxygen, nitrogen, neon, sulfur, and iron.

The Crab Nebula (which measures 11 light years across and lies 6,500 light-years from Earth) NASA/CXC/SAO/F. Seward

In the center of the Crab Nebula is a spinning neutron star which is emitting jets of particles at a tremendous velocity from its magnetic poles. These jets produce very powerful beams of electromagnetic radiation (which varies in intensity and wavelength according to elaborate nuclear & stellar physics, much of which is not yet understood).  The forces which create neutron stars often leave the stars spinning and pulsing with energy in such a way that they become pulsars.  These pulsars are useful for studying gravity, general relativity, and the behavior of matter at nuclear densities (albeit indirectly).  They also make accurate time measurement devices and useful beacons.  It is strange to think that stars so prominent for vast distances and so useful to astronomers actually have such minimal volume.

A Detailed x-ray image of the pulsar at the center of the Crab Nebula (Chandra)

So, it is not easy to do what has never been done before. In October of 2010, I wrote about the National Ignition Facility, a joint scientific project run by Lawrence Livermore National Laboratory in Livermore California.  The National Ignition Facility aims to recreate the heat and pressure of stars and hydrogen bombs on a microscopic controlled scale.   The project is ostensibly designed as a United States defense project to model the nation’s next generation nuclear arsenal without use of (treaty-prohibited) nuclear testing, but cognoscenti have long suspected that it is a way that our country can pursue fundamental energy and physics research despite the apathy (or outright animosity) of a do-nothing congress and politically divided citizenry.

One of four banks of giant capacitors which power the laser microburst

Unfortunately the facility experienced a series of setbacks, and the massive laser array did not deliver the promised energy output.  However, this month all that changed!  On July 5th the facility briefly powered up its 192 lasers to deliver a 1.85-megajoule blast that released more than 500 trillion watts of power. Although the laser beam was only active for a miniscule fraction of a second, during that brief time it was focusing a thousand times more energy than the rest of the entire United States was actively using.  Remember Doc Brown from “Back to the Future” shouting about “1.21 gigawatts!” and desperately running his hands through his hair? Well, a gigawatt is a billion watts.  This laser beam produced a 500 terrawatt blast–500 trillion watts.  So just imagine Doc shouting “1.21 gigawatts!” four hundred thousand plus times!

The successful test firing brings the NIF within tantalizing reach of their desired ignition breakthrough—the glorious moment when scientists flip a switch and create a controlled, contained fusion reaction.  Building such a “star in a jar” is the first step on a road to titanic engineering and energy-creation achievements which could reshape humanity’s place in the universe.

A day ago an international team of stellar physicists announced that the sun’s surface is covered with thousands of searing hot plasma super tornadoes each of which is the size of a large continent on Earth.  Using a combination of a space telescope and a ground telescope, researchers discovered that each of these plasma vortexes spins at velocities up to 14,500 kilometers (9,000 miles) an hour.

(CREDIT: Wedemeyer-Böhm: Parts of the image produced with VAPOR)

The mystery of why the corona of the sun is 300 times hotter than the star’s surface has long vexed scientists.  The surface of the sun is a balmy 5,526 degrees Celsius (9,980 Fahrenheit), while temperatures in the corona peaks 2 million degrees Celsius (3.5 million Fahrenheit). The discovery of these giant fast-moving storms provides a new mechanism by which heat is transferred through the sun’s atmosphere and ejected into the corona. Energy locked in the powerful magnetic vortexes is effectively self-insulated and does not heat the solar photosphere and chromosphere as much as the corona (where the storms widen and dissipate).

The Sun photographed by the Atmospheric Imaging Assembly (AIA 304) of NASA’s Solar Dynamics Observatory

Sven Wedemeyer-Böhm, a Norwegian scientist working on the team was quick to stress that the tornadoes are likely one of several complicated energy transfer mechanisms by which heat reaches the solar corona. However it seems that there are more than 11,000 of these huge plasma tornadoes on the solar surface at any given time.

A Comparison of the relative sizes of the Fomalhaut system and the solar system (image created by NASA and ESA)

Fomalhaut is a star with twice the mass of the sun located approximately 25 light-years from Earth in the constellation Piscis Austrinus.  It is a bright young star 100 to 300 million years old (out of a projected lifespan of 1 billion years). Coinicientally  the name Fomalhaut is Arabic and means “mouth of the Southern fish.”  Fomalhaut has at least one planet—Fomalhaut b, which is believed to be approximately the same size as Jupiter (but could be anywhere from the size of Neptune to 3 times as large as Jupiter).  Just as Saturn is surrounded by a ring of debris, the entire star system of Fomalhaut is surrounded by a giant toroidal circumstellar disk.   This torus is vastly greater in diameter than our entire solar system (including the Oort Belt) and is made up of somewhere between 260 billion and 83 trillion comets which are constantly colliding and annihilating each other!  The Herschel Space Observatory recently captured an infrared image of this immense comet storm.

An infrared image of the Fomalhaut system--and its huge cloud of disintegrating comets) captured by the Herschel Space Observatory (credit: ESA)

Sirius, located in the constellation Canis Majoris

The brightest star in the night sky is Sirius.  Only 8.6 million light years from Earth, Sirius A is 25 times more luminous than the sun.  Because of its brightness, the star was well known in ancient times—it was named Sopdet in Ancient Egypt and it was the basis of the Egyptian calendar.  After a 70-day absence from the skies Sirius (or Sopdet) first became visible just before sunrise near the Summer solstice—just prior to the annual Nile floods.   Greek and Roman astronomers philosophized and speculated about Sirius, (which they called “the dog star” because of its closeness to the constellation Canis Majoris).  Arabs knew the star as Aschere “the leader”.  Polynesians used it as a principle focus of their astonishing oceanic navigation.  Over countless millennia, Sirius has worked its way deep into human consciousness as one of the immutable landmarks of the night sky.

Hieroglyph of Sirius/Sopdet

So imagine the shock when it was discovered that Sirius is not alone.  The bright star we know is actually Sirius A, a star with twice the mass of the sun. In 1844 the German astronomer Friedrich Bessel hypothesized a tiny companion for Sirius based on the irregular proper motion of Sirius.  Then, in 1862, as the American Civil war was being fought an American astronomer in Chicago first observed the tiny companion, Sirius B (thereafter affectionately known as “the Pup”). Sirius B has nearly the same mass as the sun (.98 solar mass) but it is only 12,000 kilometers (7,500 mi) in diameter—nearly the same distance around as Earth.

An Artist's Conception of Sirius A and Sirius B

Today Sirius B is the closest white dwarf star to planet Earth.  However it has not always been so, Sirius B began its life as a luminous blue B-type main sequence star with a mass five times that of the sun. About 124 million years ago—as the dinosaurs grazed on the first magnolias—Sirius B fused its way through the hydrogen and helium in its mass.  As Sirius B began to fuse together larger elements like oxygen and carbon it expanded into a red giant star with a diameter 10 to 100 times that of the sun. Then Sirius B ran out of nuclear fuel.  Without the heat generated by nuclear fusion to support it, the star underwent gravitational collapse and shrank into a hyper dense white dwarf star.  These tiny stars are extremely dense and hot when they are formed, but since they generate no new energy their heat and radiance gradually radiate away over billions of years until the stars are completely black and dead.

Not this sort of "White Dwarf"--Curse you Google Image Search!

Although Sirius B is largely composed of a carbon-oxygen mixture, its core is overlaid by an envelope of lighter elements. Hydrogen, being lightest, forms the outermost layer (which is why the little star currently appears uniformly white).

NASA's Kepler Spacecraft

As I write this, astronomers know of about 700 planets which lie beyond the solar system. Yet in just 16 months, NASA’s Kepler mission has discovered an additional 2,326 potential new planets. This figure is hitting the mainstream news today thanks to NASA’s announcement that the Kepler space observatory has confirmed the existence of Kepler-22b, a planet which exists within the so-called habitable zone of a yellow G-class star about 600 light years from here.  Kepler-22b orbits its star every 290 Earth days and is reckoned to have an average temperature of about 22 degrees Celsius (approximately 72 degrees Fahrenheit).  Although closer in size to Earth than most exoplanets, the new world still has a radius which is more than twice that of our planet(which means that Kepler-22b’s mass is immensely greater).  Scientists have no idea what Kepler-22b is made of, but because of its high gravity, its atmosphere is likely to be a heavier, sludgier affair than that of Earth.

A Diagram Contrasting the Solar System with Kepler 22-b's Star System (Image credit: NASA/Ames/JPL-Caltech)

The discovery of new worlds is becoming progressively more common–which means that new planets are more difficult to write about (I can testify to this because I have been trying to think of novel and exciting things to say about this new exoplanet). The top google search result for Kepler-22b is currently a smug caricature of the foibles of earthlings.  Within a few days the sparse prose of Wikipedia’s equally scanty entry will probably be the top search result—and that is likely the way that things will remain for a long time (or forever). We are beginning to compile a massive database of different worlds.  As the numbers add up, the true stories will be within the statistical understanding of new planets–unless of course a habitable zone planet leaps out of the news with electromagnetic signatures characteristic of life and intelligence.  That result becomes progressively likely as we begin to learn where to point our telescopes.  Out of the thousands of planets the Kepler mission is finding, Kepler-22b is the first habitable zone world of dozens–or of hundreds.

Someday

[Alien clipart by Elizabeth Aragon at www.sweetclipart.com]

Eta Carinae is a star system 8,000 light years from the solar system.  It contains a luminous blue hypergiant star which probably has about 100 times the mass of the sun and shines 4 million times more brightly.  For those of you keeping tally, that gives the star approximately the same mass as 33 million earths!

Eta Carinae was originally cataloged by Edmond Halley in 1677 (hence its stylish Latin name) as a comparatively dim 4th magnitude star, however astronomers noticed that its brightness varied greatly over the decades.  In 1827 it began to become significantly more luminous and by 1843 it was the second brightest star in the night sky (after Sirius, our next door stellar neighbor which is only 8.6 light years away).  The star then dimmed down to the eighth magnitude—becoming invisible to the naked eye.  Today it is believed that this strange occurrence was a supernova impostor event in which the star nearly exploded.  Looking at Eta Carinae now through the Hubble telescope reveals two huge hemispheres of material ejected from the star.   Scientists have named this cloud the Homunculus nebula and it is nearly a light year in diameter.

Eta Carinae and the Homunculus Nebula as photographed by the Hubble Space Telescope

Stars as massive as Eta Carinae are very rare.  At this stage of galactic development there are perhaps a dozen in a galaxy the size of the Milky Way (which contains 200 billion to 400 billion stars).  Eta Carinae is probably fated to die in a hypernova explosion (an immense supernova event).  A similar impostor event to Eta Carinae’s 1843 flare-up was witnessed on SN 2006jc, a star within galaxy UGC 4904 (perhaps you now appreciate the Latin and Arabic names of familiar nearby astronomical objects).  SN 2006jc went hypernova two years after its impostor nova event.  It is very possible that Eta Carinae no longer exists but was destroyed a long time ago.  The light we see now is eight thousand years old.  Who knows what happened since then?

When Eta Carinae goes hypernova it will destroy star systems nearby.  Additionally,  a massive gamma ray burst will shoot from both of its poles as its center collapses into a black hole. Any living, earth-like world caught in such a beam would be sterilized completely–although we are mercifully not currently in Eta Carinae’s polar vector…

Eta Carinae’s Fate? A Hypothetical Illustration of a Hypernova Event with Gamma Ray Burst (Credit: Nicolle Rager Fuller/NSF)

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