A Possible New Planet Around the Second Closest Star System to Earth

An international team of astronomers is announcing the possible discovery of a planet around the second closest star system to us, Barnard’s Star. A mere 6 light-years away, the star is a faint red dwarf which gives off only four hundredths of a percent of the Sun’s light energy. The planet, which could be as massive as 3 Earths, is orbiting at the same distance as Mercury is from the Sun, but is still colder than Saturn and unlikely to harbor life as we know it.

Since the closest star system to us also has a known planet in it, this discovery (if it is confirmed) would make it even more likely that planets are “more common than dirt” out there. Four planetary systems would then be known among the stars 10 light-years or closer. Some 2900 planetary systems (containing almost 4,000 planets) have now been found in our galactic neighborhood.

The new planet, which takes 233 days to orbit, was detected from the very slight “wiggles” that the planet’s gravity (as it goes around) gives to the motion of its star. The wiggles are so small that it took 20 years of observations, using special equipment on various telescopes around the world, to identify them. While it’s still possible that their combined observations have another explanation, the 63 authors on the paper announcing the planet have dug deeply into their data statistics and claim that the planet idea is the most likely explanation. Not all experts in the field agree that this is a definite detection. Instruments of the future, with better ability to detect tiny star wiggles, will ultimately decide if the planet is real.

Our image shows an artist conception of what the the “cold, hostile desert” surface of the planet around Barnard’s Star, with a temperature of -270 degrees Centigrade, might look like. (You will need to take your parka if you go.)

A Sparkling Cluster of Stars from the Hubble

Here is a beautiful new image from the Hubble Space Telescope, showing a young cluster of stars called Trumpler 14.

Located about 8,000 light years away in the constellation of Carina, this grouping of hot bright stars formed only recently from a great cloud of cosmic raw material, called the Carina Nebula. It is one of the great ideas that we now know about how stars live that the more massive a star, the brighter it shines, and the shorter its life-span will be before it "burns out." Superstars die first, is the general rule.

Because Trumpler 14 formed only about 500,000 years ago (which is a very short time on the cosmic scale), this group still includes a lot of bright superstars, which dominate our image.

Robert Trumpler (1886-1956) was a Berkeley astronomer, who compiled a very useful list of star clusters (places where dozens to thousands of stars are born together.) An annual award at the Astronomical Society of the Pacific, honoring the best PhD thesis in astronomy in North America, is named in his honor.

In our picture, you can see a jewel-like display of bright stars in front of the glowing gas and dust of the nebula. The stars in this cluster are one ten thousandth the age of our Sun. Mere babies, really!

Click on the photo to enlarge it and see it even better.  

A Beautiful Image with a Nice Ring To It

Here is a dramatic image of a dying star, courtesy of amateur astronomer and master photographer Robert Gendler. Called the "Ring Nebula," this cloud of of expelled material surrounds a star somewhat like our Sun, but further along in its life cycle.

Usually, regular telescopes only show the inner glowing part that you see in bluish green in the center. But Dr. Gendler has combined the visible-light image with fainter, cooler infra-red information to show how the star has expelled material not just once, but many times. You can see shell after shell surrounding the star. Like a dying man in those old Victorian novels, who coughs and coughs for months before death releases him, this star has been "coughing up" its outermost layers, as it adjusts to the final internal collapse. After the expanding shells have moved away, what will be left is a dense, hot "star corpse" astronomers call a white dwarf.

The image pixels come from the Hubble, Subaru, and Large Binocular Telescopes. By all means click on the picture and look at the larger version.

The Ring Nebula (a favorite astronomical object for newlyweds) is about 2000 lightyears away in the constellation of Lyra. It is perhaps the best known example of a "planetary nebula." (The name comes from their fuzzy appearance in early telescope; the expanding shell of gas has NOTHING to do with planets.) Astronomers also call it M57 (the 57th entry in Charles Messier's catalog of fuzzy objects in the sky.) If you search for M57 on the web you can learn a lot more about it; or just enjoy the weirdly wonderful picture.

Robert Gendler's other astronomy images can be found at: http://www.robgendlerastropics.com/  

To see a larger version of the amazing Hubble Space Telescope image of this object (which is at the center of our picture), go to: http://hubblesite.org/newscenter/archive/releases/2013/13/image/b/format/large_web/ 

New Evidence that We Live in a Space Bubble

Many people enjoy talking about their neighborhood, and how well they've come to know it. But do you know much about the "neighborhood" that our Sun and its planets hang out in? New evidence from an instrument launched aboard a NASA rocket has confirmed that our cosmic neighborhood really is a big bubble.

We have known for some time that our solar system sits inside a region which is emptier than the typical neighborhood in the Milky Way Galaxy. This "Local Bubble" (as it is called) is about 300 light years across, meaning light would take 300 years to cross it. Our diagram shows the bubble and some of the bright stars that are located in it. (The stars that looked brightest to our ancestors are the ones that wound up getting names. Many of the names we use today are Arabic translations of ancient Greek names.)

The Sun is actually located in a region that has a bit more loose gas and dust that the bubble. We call our slightly denser region the "local fluff." You can see the local fluff and other slightly denser regions inside the big bubble in yellow on our picture.

But what made this bigger bubble that we sit inside? Our best idea was that the violent explosions of giant stars ("supernovae") carved out this emptier region perhaps 10 or 20 million years or so ago. Some astronomers were not convinced of the exploding-stars origin of our bubble and thought that we might be fooled by some ways that our Sun's wind (the flow of atomic particles boiling off our star's surface) is interacting with the material in the fluff.

A new instrument, which looked for x-rays that come from collisions of atoms in deep space, was launched in 2012 aboard a rocket and got to spend five minutes above the Earth's atmosphere, where cosmic x-rays can be monitored. The data collected from those five minutes (!) was enough for the astronomers to confirm that the violence of exploding stars was the major contributor to the signs of the local bubble.

The exploding stars were not close enough to the Sun and the Earth to hurt life on our planet significantly -- after all, life on Earth thrived earlier than 10 million years ago and still thrives today. But it's clearer and clearer to astronomers that exploding stars have a lot to do with the geography and chemical makeup of our Galaxy. They not only made the bubble we find ourselves in, but we also know that it is the death of these stars that recycles the elements they get to make in their hot centers. This enriches the neighborhood with atoms like carbon, oxygen, and nitrogen -- the chemical building blocks of life as we know it. (Just about every atom of calcium in your bones, for example, was actually once inside a star that later exploded.)

By the way, our cosmic bubble is by no means unique. Other bubbles have been discovered near and far, blown by countless other star explosions over the 13 billion-year history of the Milky Way Galaxy.

For more technical details about this research, see the nice Science@NASA newsletter at: http://science.nasa.gov/science-news/science-at-nasa/2014/26aug_localbubble/

Finding an Invisible Star Corpse

An international team of astronomers recently reported a wonderfully strange discovery.  They found the faint, cold "corpse" of a dead star, not by detecting any light from it, but through its gravity grip on another star corpse with which it shares a system.  It's quite a story!

To follow it, we need to take a brief excursion into the gruesome deaths of stars.  All stars collapse at the end of their lives, but stars with different amounts of mass (stuff) die differently.  Less massive stars (like our Sun) eventually die by collapsing into a ball not much bigger than a planet -- such a white-hot but tiny corpse is called a "white dwarf."  They start out as really hot, but cool off as they shine away their light and heat into the darkness of space.

More massive stars have a more complicated death in store for them. They die in a sudden event, where the core of the star collapses catastrophically, while the rest of the star blows up in a giant explosion called a "supernova."  We have discussed such explosion in several posts. 

What interests us today, however, is the tiny core of the star which is super-squozen (that's a technical term!) by the star's death.  It's typically not much bigger than your average suburban town, and called a "neutron star" -- because in it all the atoms lose their identity and become neutrons.

Such a neutron star, surrounded by an "atmosphere" of materials from the messy explosion of the rest of the star, can sometimes be detected by faint pulses of radio waves it gives off, and is then called a "pulsar."  (A watch company "borrowed" that name, but we astronomers had it first.)

So now here's the discovery.  Astronomers using radio telescopes first discovered a pulsar in the constellation Aquarius, indicating that a neutron star was revealing itself to us.  But the pulsar showed signs of wobbling, as if something with strong gravity was orbiting around it and pulling on it.  Careful measurements reveal that the orbiting object is a white dwarf, and it takes only two and a half days to revolve around the neutron star. (Remember that Earth takes 365 days to go around the Sun, so these two star corpses are in an intimately close dance.)

To their amazement, when other astronomers tried to find the light or heat of the white dwarf companion, they COULDN'T -- not even with the biggest telescopes.  That white dwarf must be so old that it has cooled down below the level where we can find it (at its distance of about 900 light years.)  This makes it the coldest, dimmest star corpse ever found.  If you are into star corpses, and we astronomers really are -- this is a big deal.  It's remarkable that with today's technology, we can know this white dwarf is there not by its light, not by its heat, but just by its pull on another dead star nearby. 

Note: Our image is just a painting, not any kind of photograph.  It shows the pulsar on the left (with two beams of radio waves coming from it) and the white dwarf on the right.  Although we can see light coming from the white dwarf in the painting, in real life the star is so faint and far away, no light from it is detectable with today's instruments.

Cosmic Fireworks

For those of you who don't get to see fireworks today (July 4), here is an image of cosmic fireworks for your enjoyment. The glowing ring on our picture (taken with the Hubble Space Telescope) shows material ejected long ago from a star whose total explosion we saw in 1987. Recently, earlier debris from the star has been hit by the fastest moving material from the star's final explosion. The shock of collision has set knots of thicker material in the ring to glow like a necklace of sparklers.

The dramatic explosion at the end of the life of a star is called a "supernova," and this particular supernova is located in one of our closest neighbor galaxies, the Large Magellanic Cloud, about 168,000 light years away. We wish it were closer, but a visible supernova is a rare event. This was actually the first supernova explosion we have been treated to since the invention of the telescope in 1609-1610. It's been given the extremely clever name Supernova 1987A (the first such explosion seen in 1987.)

The huge star whose explosion we saw in 1987 had been losing some of its mass in earlier periods of its life and was surrounded by a cloud of its own debris. Later a wind of hot particles had blown from the star as it went through a different stage of its development. That wind had made a cavity in the gas around the star.

Now the material from the star's actual explosion, which has been moving for 27 years at great speed, has reached the inner walls of this cavity and is colliding with thicker blobs of the older material. That's the glowing ring we see so clearly in the Hubble image.

If you want to see a time lapse movie made of Hubble images taken each year as the ring started lighting up, you can see it at:
http://en.wikipedia.org/wiki/SN_1987A#mediaviewer/File:SN1987a_debris_evolution_animation.gif

Happy fireworks day!

A Possible Sister Star that Formed with Our Sun

Astronomers now know that stars, like people, tend to be sociable. Stars are often born and hang out in groups -- double stars, triple stars, star associations, and star clusters.  Yet our Sun is a single star, surrounded only by its family of planets and moons, but no sibling star to keep it company.  Was it always this way?

In recent years, it's become clearer that our Sun could well have formed in a loose group of thousands of stars, when it first "clumped" out of the gas and dust (raw material) of the Galaxy some 5 billion years ago.  If our mother cluster was indeed just loosely held together by the mutual gravity of the stars, in all that time, the stars could have drifted apart -- as many families do in the busy course of life. 

So we have been on the lookout for the Sun's now far-away sisters. This past week, a team of astronomers, headed by Ivan Ramirez of the University of Texas, announced that they might have found our first long-lost sibling. 

There are perhaps as many as 400 billion stars in our Milky Way Galaxy.  How can we possibly find our sisters in that huge and anonymous crowd?  After all, there are no star birth certificates on file at county offices and no little tags that hang around a star's neck.  The search involved two factors: First they looked for stars that have the same chemical make-up as the Sun (they consist of the same proportion of elements) -- which you'd expect from stars born in the same"womb."  And then they searched for stars whose motion could be calculated backwards in time and would have placed them close to us 5 billion years ago. 

Sorting through 30 possible candidates identified by other groups of astronomers after painstaking work, Ramirez' group came up with exactly one star that fit all the criteria.  Called by its catalog number, HD 162826, it's 110 light years away now, in the constellation box called Hercules.  (See the map.)  It has 15 % more mass than the Sun, and so it is a little brighter and a little hotter than our star. (In astronomy jargon, it's a Type F star, while our Sun is Type G.)

It turns out that HD 162826 has been searched for planets for the last 15 years, and so far, no planets have turned up.  But the kind of search it has been subjected to can't find small (Earth-like) planets. So the we have a long way to go before we can decide it the star has a planetary system around it or not.

Future surveys, allowing us to analyze the make-up of fainter stars, could well turn up other family members out there.  For now, astronomers will keep a far closer eye on this one possible sister star and follow it as it goes about its life.  Who knows, one day, someone from there may just respond to the equivalent of a cosmic blog post.

Astronomer Discovers the Fourth Closest Star System to Us -- And It's Cool!

Just last year, I posted the news that astronomer Kevin Luhman of Penn State had discovered the third closest star system to our own.  It consisted of a pair of failed stars -- stars containing too little material to shine consistently with visible light and thus commonly called brown dwarfs.

Now Luhman has done it again.  He recently announced the discovery of the fourth closest system -- this one consisting of the coldest brown dwarf ever found.  Known only by a long catalog number giving its cosmic "latitude and longitude" (WISE J085510.83-071442.5), the wanna-be star is 7.2 light years away.  That's right in our neighborhood as far as astronomical objects are concerned.

Our best estimate of its mass is that it weighs only as much as 3 to 10 Jupiters.  So, really, it could be more of a free-floating planet rather than a brown dwarf.  But since brown dwarfs are more common (planets are found more frequently around stars than by themselves), the discoverer is betting it's just a very cold and poorly endowed brown dwarf.

The image accompanying this note is just an artist's conception of what such a cold, failed star might look like.  After observing it with a variety of space-based telescopes (such as WISE and Spitzer, which are sensitive to infra-red or heat rays and not light), Luhman and his colleagues estimate that the outer temperature of this strange neighbor is as cold as the Earth's North Pole.  (Estimates vary from -54 to 9 degrees Fahrenheit, or -48 to 13 Centigrade.)   So its outer layers are like those of the giant planets far from our Sun, and nothing like a real star.  Stars have temperatures thousands of degrees hot.

What is remarkable to me is that, after 400 years of using telescopes, and more than 50 years of instruments in space, we are still discovering our closest neighbors!  It's not our fault, of course -- this neighbor was very shy, not shining with the kind of rich light power that our closest neighbor, the triple star system Alpha Centauri, gives off.  And in space, as on Earth, it's often the show-offs that get the attention.

An Interview with the Father of the Search for Extra-terrestrial Intelligence

In 2012, during a weekend astronomy event (called SETICon II), I had the pleasure and privilege of doing a 45-minute on-stage interview with Frank Drake, the distinguished astronomer who did the first scientific experiment searching for evidence of intelligent life among the stars. The interview was videotaped at the time, but not released.

Now, to celebrate the beginning of the 30th year of the SETI Institute (the organization engaged in continuing that search), they have released the interview on YouTube and you can see it at:
http://www.youtube.com/watch?v=HPQz-kdaxNo

Dr. Drake was the first President of the SETI Institute, and I have been a board member there since the beginning. We discuss both his career and his current thinking about the search, including his current view of the Drake Equation (a way of estimating the chances of intelligent life out there). He also reflects on a number of modern developments, including the discovery of numerous planets orbiting other stars and novel ways of searching for extra-terrestrial civilizations.

For more about the non-profit Institute, you can explore their web site at: www.seti.org

A Star Explodes in a Nearby Galaxy

The big news from the world of astronomy is that a star has blown itself to pieces in a galaxy not so far, far away. The galaxy has the catalog number M82, and is only between 11 and 12 million light years away. (The nearest independent galaxy is a bit more than 2 million light years away, so, as galaxies go, M82 is one of our neighbors.)

M82 is located in the constellation of Ursa Major (the Big Bear), the same constellation that contains the well-known star pattern called the "Big Dipper." That means it is an easy target for telescopes in the Northern Hemisphere of our planet right now. Both amateur and professional astronomers are glued to their instruments, viewing and analyzing this doomed star.

Our color image, which shows the explosion -- called a supernova -- with an arrow, is from the Katzman Automatic Imagining Telescope at the Lick Observatory near San Jose (It was sent to me by Berkeley astronomer Alex Filippenko, who leads the project to discover exploding stars with this telescope.)

Astronomers are looking at the spectrum (the many different colors of light) from the exploding star. They have already discovered that this is that special kind of supernova which helped astronomers discover that the expansion of the entire universe is speeding up -- and earned them the 2011 Nobel Prize in physics.

Called a Type Ia supernova, this kind of explosion comes when a star corpse called a white dwarf is briefly re-ignited by sucking material from a close neighbor star (don't make any zombie jokes, please.) The energies involved when the white dwarf is overloaded with hot new material and blows up are so great that there is no earthly counterpart to compare them to. We are already seeing material blasting away from the explosion at speeds of 45 million miles per hour!!!

Since these supernovae are so important for understanding the universe (not just its expansion, but also its extent and how the death of old stars leads to the birth of the next generation), we are always grateful to have a nearby example to study.

If you have a telescope and want more information on how to find the galaxy and what equipment you will need to observe the supernova, see the Supernova 2014J pages at the website of Sky & Telescope magazine:http://www.skyandtelescope.com/observing/highlights/Bright-Supernova-in-M82-241477661.html

Why There is Always a Lot of Astronomy News in Early January

I'll share a little secret with you. If you follow astronomy developments, you might have noticed that there are a lot of news stories that come out at the beginning of January. The reason is that the nation's professional astronomers have their big meeting each year in early January, and many universities and observatories save up their big announcements to coincide with a talk or paper being delivered at that meeting.

This year was no exception -- many thousands of astronomers gathered for the winter meeting of the American Astronomical Society in National Harbor, a shopping-center-ambiance convention center (and tourist trap,) a short distance from Washington, DC. I was only there at the beginning, leading a workshop on education for young astronomers, because I had to get back for the start of the winter quarter at Foothill College. But the cosmic news stories were descending on us thicker than the snow in the northeast in the same week.

Here are just a few of the "stellar" news items from the week:

* The Kepler mission (searching for planets orbiting other stars) announced the confirmation of several dozen planets among the thousands first glimpsed with Kepler. Among them were five rocky planets bigger than Earth. Two of them are 40% bigger than our planet and have densities similar to lead!

* Scientists working with the Spitzer Space Telescope -- which views the universe of heat rays (infra-red) and not light -- made observations of brown dwarfs (failed stars). They found that many of them have huge storms in their atmospheres (like the giant storm on Jupiter we call the "Great Red Spot.") The stormy atmospheres of these stars is what the artist's impression in the accompanying image tries to show. Such storms probably have giant lightning bolts and torrential rain. But it's too hot for the rain to be water, so the droplets could hot sand, molten iron, or salts. Bring a strong umbrella if you go.

* A graduate student at Vanderbilt University has discovered what appear to be ordinary stars that have been kicked out of our Galaxy at speeds of a million miles per hour. Such "hyper-velocity stars" have been found before, but they were thought to be a special category of big blue stars kicked out by unfortunate encounters with the monster black hole at the center of the Milky Way Galaxy. The ones in the current study come from the direction of the main disc of our pinwheel shaped galaxy, not from the the center. So what could have given them such enormous speeds is a complete mystery.

I will tell you about other discoveries in future posts. In the meantime, if you have some science background and want to see what it feels like to be a science reporter at one of these meetings, you can go to the page where the Society archives the press conferences:
http://aas.org/media-press/archived-aas-press-conference-webcasts
and check out one or two of them. Or just take a minute and contemplate how really alien and strange the worlds beyond our planet are turning out to be.

A Triple System of Star Corpses

An international team of astronomers has just reported the discovery of one of the weirdest star systems we have ever seen -- a triple system of star corpses (dead stars) whirling around each other in a space smaller than the Earth's orbit around the Sun.

The system of stars is more than 4,000 light years away, in the constellation of Taurus. (But this story is no bull!) The system doesn't have a name, only a catalog number.  It consists of one "neutron star" (which pulses with radio waves) and two "white dwarfs."  Generally, a tiny "neutron star" only forms after a massive star dies by blowing itself to pieces, leaving a very compressed remnant (or "corpse") behind.  So, those three stars, which show evidence of having formed together, had to remain together even when the biggest star of the three exploded.  Later, the two smaller stars died and also became compressed objects (not much bigger than a planet) called "white dwarfs."  (They get that name because they are small and white hot.)

Now the three corpses continue to spiral around each other, in a strange cosmic ballet .  The heaviest corpse, the "neutron star" is really dense -- it is so compressed that to make something like it on Earth, we would have to take all the people in the world and squeeze them into a raindrop!  (Then we would have one rain-drop sized piece of the neutron star.)

Sometimes we see such "neutron stars" giving off spinning magnetic beams of radio waves.  Whenever such a radio beam sweeps over the Earth, we get a pulse of radio waves.  In such cases, we also call these dead stars "pulsars."   Their beams of energy can be timed with great accuracy.

In 1974, my former college advisor, Joseph Taylor (and Russell Hulse,) discovered the first pulsar in a double star system.  Measuring its pulses enabled them to verify important predictions of Einstein's General Theory of Relativity, and earned them the 1993 Nobel Prize in Physics.  At the time, astronomers thought that finding a neutron star/pulsar with a companion was pretty surprising (although today other double systems are known.)

Now suddenly, we have a neutron star/pulsar with TWO companions.  How completely and wonderfully weird!  And this particular neutron star spins hundreds of times per second. Its fast spin and two companions will allow astronomers to measure the predictions of Einstein's theories even more precisely than we have been able to do in the past.

Galaxy Cluster Abell 1689 Breaks Two World Records

A huge cluster of galaxies so far away that light from it takes 2.2 billion years to reach us has revealed itself to be a record-breaker. It has the largest number of star clusters ever seen in one place and it is farthest place in the universe where we have seen star clusters.

To appreciate this story, you have to distinguish between the two kinds of clusters we're discussing. Stars are often born in groups called "star clusters" and the largest and most impressive of these are called "globular clusters" (because their stars are organized into a big globe-shaped collection of 100,000 stars or more.) Our Milky Way Galaxy has about 150 of these globular clusters and they are among the oldest and most crowded places in our home galaxy.

Galaxies -- the great islands of billions of stars -- also turn out to be organized into clusters. Each cluster might contain hundreds or even thousands of galaxies. (And each galaxy contains billions of stars -- it makes you dizzy if you think too hard about it!)

The late George Abell (an astronomer at UCLA and the author of a famous textbook from which astronomers in my generation first learned astronomy) made a catalog of these galaxy clusters, and the one we are discussing is entry 1689 in his catalog.

A new study of the central region of Abell 1689, made with the Hubble Space Telescope, reveals 10,000 globular clusters of stars in a small region of the galaxy cluster. The astronomers who carried out the work estimate the throughout the entire galaxy cluster, there may be as many 160,000 of these giant old star clusters -- a record unequaled anywhere else we have looked so far.

At a distance of 2.2 billion lightyears, Abell 1689 is also the farthest location in the universe where we have seen a globular cluster.

In the attached picture, you can see part of the cluster of galaxies on the left and then a close-up where the globular clusters look like little yellow dots among the bigger galaxies.

For a scan through the galaxy cluster, you can check out this YouTube video: http://www.youtube.com/watch?v=bumxssc9Cdo
(On this scan, you can also see faint rounded arcs of light -- those are direct proof of one of Einstein's ideas -- that the huge gravity of the galaxy cluster acts like a "gravitational lens" and bends the light of other galaxies behind it into arc like shapes.

We have seen other rich clusters bend light from objects behind them, but the effect is especially clear on this beautifully detailed image. 

Hints of Water on a Super-Earth

A Japanese team of astronomers, using the giant Subaru telescope, atop an extinct volcano in Hawaii, have found further hints of the presence of water on a planet orbiting the star Gliese 1214, about 40 lightyears away.

The planet orbits its star in only 38 HOURS (not days, folks, but hours!) You might think that a planet this close to a star will soon be french fried, but, in this case, the star itself is much dimmer and cooler than the Sun -- it is what astronomers call a "red dwarf."

The planet circling the red dwarf is one of the few planets outside our own solar system which we have been able to find in two independent ways. We know it's there because its gravity makes the star wiggle a bit, and we also know it's there because we can see the planet move across the face of the star and cause a mini-eclipse (or transit).

This double identification is very helpful, since it lets us measure both the size of the planet and how much stuff (mass) it contains. That's how we know it's a "super-Earth" -- a kind of planet we don't have in the Sun's family. This super-Earth is about three times the size of Earth, and more than 6 times its mass. These characteristics make this alien world denser than Jupiter but less dense than Earth. It could be a little rocky planet with a giant atmosphere, or a planet with some rock and a lot of liquid water surrounding it.

The new Japanese study examined the planet's atmosphere and concluded that the way light of different colors scattered from it was consistent with either the presence of water vapor or with some kind of extensive cloud cover. Combining this work with other studies makes astronomers a bit more sure that this is a water-rich environment. That still doesn't help us pin down exactly what this super-Earth looks like, and it's probably too warm overall for life as we know it. Nevertheless, isn't it amazing that we can now discover not only planets out there in other parts of the Galaxy, but even something about the kind of air they have surrounding them?

(NOTE: The image above is an artist's conception of what the star might look like through a blue filter.  The star itself would look red to your eye.  The planet is the smaller black sphere on the left side of the star.)

As the World Turns

It's a dizzying thought, but the solid ground beneath our feet is moving at great speeds through space. For example, our planet turns once a day. Every 24 hours, the place where you live on the surface of the Earth goes in a big circle around the center of our planet. In the San Francisco Bay Area, this motion happens at a speed of about 818 mph. (Children, you can do this without adult supervision, because gravity holds all of us firmly to the Earth's surface.)

Our planet turns around an imaginary stick that goes from the Earth's north pole through its south pole. We call the line of that imaginary stick the Earth's "axis." As our planet turns around its axis, the Sun appears to rise in the East and set in the West and we have day and night. At night, as we turn, we see everything in space slowly turning around us. But we know the Sun during the day and the stars at night are not really turning. They sit in space and mind their own business. The motions we see in the sky hour by hour just reflect the turning of planet Earth. Do you want to see this motion displayed?

On the magnificent photo I have attached to this little posting, you can actually see the turning of the stars (around the still point of the north pole of the sky). Master photographer Phil McGrew captured the turning of the sky above the Golden Gate Bridge. I was so enchanted with this photo, I asked him to give me permission to share it with all of you. You can see more of his photos at his web site: http://www.philmcgrew.com/

The photo is actually made up of more than 180 20-second exposures, skillfully added together. Instead of being a point, each star becomes a curved line as the Earth turns with the camera and photographer attached to it. Astronomers call the curved lines "star trails."

Can you think of other ways that you are moving even while sitting still in your favorite armchair? We'll discuss these other motions in future posts.

Stunning Wide-Field Image of a Star Nursery

Every once in a while, I see a new astronomical picture that leaves me with my mouth open, saying "Wow!" The above image, assembled by a talented amateur astronomer, from information taken by a number of different telescopes, is one of those.

This wide-angle view is centered on a cluster of recently-born stars that is known by its catalog number of NGC 2264. Surrounding the adolescent stars is a whole region of cosmic gas and dust -- the raw material from which stars are born. The nearby gas glows with the characteristic red color of its most common constituent -- hydrogen.

At left center is the Cone Nebula, a region of gas and dust in the shape of a sideways dark cone; the energy of bright stars to the right of the cone is eating away at the sides of this thick dusty region, leaving only a cone of thicker material behind.

To the right of the Cone Nebula, you can see an opposite (larger) cone pattern of bright stars stretching rightward. Some people see the lights of a sideways holiday tree in the pattern of bright stars.

At the bottom center of the image, pointing upward into the bluish emptier region (where the energy of freshly made stars is clearing things out), you can see an odd region of gas and dust that is sometimes called "The Fox Fur Nebula." Click on the picture and take a good look -- can you see the head of a furry red fox pointing upward into the bluish region?

The entire complex of stars and gas and dust is about 2,600 lightyears away, which means the light we see tonight left this region about 2,600 years ago -- a time when humans on Earth lived a much more challenging existence and lifespans were less than half of what we enjoy today.

This remarkable picture was assembled by Dr. Robert Gendler, a physician and amateur astronomer, who is a master at working with photographic information using his computer. The image was constructed from information provided by the Subaru Telescope in Japan and the Digitized Sky Survey, put together by astronomers at the Space Telescope Science Institute from a number of earlier surveys of the sky. To see more information about the photo, see:
http://www.robgendlerastropics.com/Cone-Subaru-DSS.html

You can go to Dr. Gendler's home page at that site and then browse his many other wonderful images. But take a minute and just enjoy a full-screen version of the picture -- you are seeing the same process of star birth that gave rise to our Sun some five billion years ago.

Galaxy with a Tail Shows How Some Galaxies Run Out of Gas

In a galaxy with lots of raw material (like our own Milky Way), baby stars are forming all the time.  But some galaxies have run out of the gas (and dust) for making new stars, leaving them barren, with no further opportunities for "childbirth."  Now a new observation of a small galaxy shows how the raw material for stars can be stripped out of a galaxy by outside circumstances.

This is not the first time astronomers have been intrigued by the appearance of the little galaxy known by its catalog number IC3418.  In 2010, the GALEX satellite observed ultraviolet light from the galaxy and first revealed that it had a "tail" -- streamers of gas that had been removed from IC3418 and were following behind it.  Now, new research gives us a better understanding of just how the little galaxy got stripped of its life-giving gas.

IC3418 is falling through a giant collection of galaxies called the Virgo Cluster.  Consisting of some 1,500 galaxies and lots of superhot gas, the Virgo Cluster is our nearest big cluster of galaxies.  Because the Virgo Cluster is full of hot gas, when little IC3418 falls through it, its own gas is stripped out.  (The cluster's hot gas can't affect the stars of a galaxy, which are heavy, but can strip away the lighter gas.)  It is this stripped away gas you are seeing as a tail in our picture.  The removed gas makes some new stars as it gets compressed and it's their glow we see.  But by leaving its parent galaxy, the gas in the tail deprives IC3418 of the fresh gas it needs to make new stars.

This makes IC3418 an old barren galaxy long before its time. It's as if the interaction with the big Virgo Cluster made it age right before our eyes.  The stripping of gas works so well because the speed with which the little galaxy moves through the cluster is 2 million miles per hour!  (Don't try speeds like this at home without adult supervision.)

For a beautiful picture of some of the thousands of galaxies that make up the Virgo Cluster, check out: http://apod.nasa.gov/apod/ap110422.html

The new observations were reported by a team led by astronomer Jeff Kenney of Yale, and were reported at the meeting of the American Astronomical Society going on this week in Indianapolis.

Black Hole at Center of the Milky Way is Found to be Cooking its Dinner

Astronomers working with the European Herschel Space Observatory have discovered really hot gas in the vicinity of the monster black hole at the center of our Galaxy. Over the years, many lines of evidence have shown us that there is a black hole with enough material to make 4 million Suns at the heart of the Milky Way. The new observations, made using infrared (or heat) rays, show that gases such as water vapor and carbon monoxide have been heated to about 1000 degrees Centigrade within a lightyear of the black hole.

While energy from nearby stars may also be heating this inner gas, the astronomers can't account for so much heat from stars alone. They think that great streamers of gas heading toward the black hole may be colliding and the shock waves from the collisions may be significant contributors to the heating. Some of the streamers of gas will someday be "eaten" by the black hole. In other words, like many a hungry diner, the black hole appears to be "cooking" its dinner in anticipation of eating it.

In fact, other observations have recently shown a cloud of gas weighing as much as several Earths, falling to its doom much closer to the black hole. This cloud may be consumed by the black hole as soon as the end of 2013. When such clouds actually spiral inward to their doom, they heat up a lot at the end. The last thing we observe from them before they fall into the black hole (and are no longer visible) is a "burp" of x-rays. Several x-ray telescopes in space are prepared to record such burps when they happen.

If you are cooking a barbecue this Memorial Day Weekend (a holiday in the U.S.), you can enjoy the idea that some serious cooking may also be going on at the center of our Galaxy. The center region is 26,000 lightyears away from us, so none of this poses the least danger to planet Earth and its cooks.

(By the way, to see one of the lines of evidence for the existence of the monster black hole, we recommend a great new movie made from observations by astronomer Andrea Ghez' group at UCLA. The movie shows the whirling orbits of stars very close to the black hole, being pulled around by the enormous gravity of the black hole. Check it out at:

http://www.astro.ucla.edu/~ghezgroup/gc/images/media/ghezGC_comp3-18_H264_864.mov

Note that each second of the movie shows two years of star motion. It's enough to make you dizzy.)

Third Closest Star to the Sun is Not A Star At All

The third closest star system has recently been found and it turns out to be a pair of faint "brown dwarfs" -- failed stars that just don't have what it takes to be a full-fledged sun. The new system -- known as Luhman 16, after its discoverer -- is 6.6 light years away. This means that light traveling from there to us would take a bit more than six and a half years to cross the distance between us. (The nearest star system is about 4.4 light years away, and the second nearest is 6 light years from us.)

I heard about this system from Dr. Gibor Basri, one of the discoverers of brown dwarfs, who gave a talk in the Silicon Valley Astronomy Lecture Series, which I have the privilege of organizing and moderating. Brown dwarfs were first named as part of her thesis by Jill Tarter, now the leading scientist searching for signs of extra-terrestrial intelligence, but then a graduate student getting her PhD at Berkeley. They are globes of hot gas that just don't have enough material to sustain the vast release of nuclear energy which powers ordinary stars.

It's the same in space as in Hollywood -- not everyone has what it takes to be a star. Just as many actors with ambitions to be in the movies wind up waiting on tables in Los Angeles, not every ball of hot material in space gets to be an on-going star. Some just glow briefly, especially with heat-rays (infra-red), but then slowly fade away. In fact, it was with the WISE infra-red telescope that astronomer Kevin Luhman discovered the brown dwarf system which now joins our list of intimate neighbors in space. (Its other name is WISE 1049-5319, which is a code that tells astronomers its location in the sky.)

In the picture with this article, you can see a later image of the system, taken with the giant Gemini telescope in Chile, that allowed astronomers to see that there were actually TWO brown dwarfs in the same star system, orbiting each other. We estimate they take about 25 years to go around. Interestingly, the Luhman 16 system is not only our third closest neighbor, but now appears to be the closest neighbor of our closest neighbor, the Alpha Centauri system. In other words, if you lived in the triple star system we call Alpha Centauri, and someone asked you, what's your closest neighbor in space, you would say Luhman 16. (Until recently, we thought WE were their closest neighbor, just like they were ours. But the brown dwarfs, which lie in the same rough direction as Alpha Centauri, but beyond them, now take our place as their closest neighbor.)

It's remarkable that something this close was just discovered. But that is a testament to how faint these failed stars really are. We are therefore able to find only the closer ones and many others that are further away remain undiscovered. The first brown dwarf was only found in 1995; today hundreds are known (thanks mostly to the WISE telescope.)

Dr. Basri's talk was videotaped and will eventually be up on our new YouTube Channel for the Silicon Valley Astronomy Lectures. You can go there now and see many other talks by noted astronomers: http://www.youtube.com/SVAstronomyLectures/

A Gorgeous New Hubble Image and News from Kepler

Scientists working with the Hubble Space Telescope have just released a magnificent new image of one my favorite astronomical objects -- the Horsehead Nebula, a great cloud of "cosmic dirt" in the constellation of Orion. What makes this image a little different from usual is that we are not seeing the tower of dust with visible light, but with heat-rays (what scientists call the "infra-red.") 

It is in such clouds of dust and gas that new stars and planets are being regularly born. Because dust can block regular light, infrared images like this allow us to peer deeper into these regions of star birth. This particular image is about 2.5 light years across (where each light year is about 6 thousand billion miles) -- so we are seeing a good-sized pillar of cosmic "raw material" here. (Yet the Horsehead is just a part of a much larger complex of gas and dust called the Orion Molecular Cloud, which is roughly 1500 light years away from us.)

You can see two recently born stars at the top ridge of dust in the Horsehead in this image, confirming that star birth is happening in this dusty clump. Note that the colors we see on this picture are not real (since these are rays our eyes are not sensitive to.) The colors were picked by Hubble scientists to give a sense of the dustiness of the Horsehead.

You can contrast this infrared picture with a visible-light Hubble image taken with the Hubble in 2000-2001:
http://hubblesite.org/newscenter/archive/releases/2001/12/image/a/

and with an image of a larger region around it taken with the Canada-France-Hawaii Telescope on the ground at:http://www.nasa.gov/multimedia/imagegallery/image_feature_89.html

Aren't they gorgeous images?

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In other news you may have read that the Kepler mission, photographing 150,000 stars regularly in its search for planets orbiting other stars, has found three more planets that are just a little larger than Earth and orbiting in the "habitable zone" of their stars -- where water could be warm enough to be liquid. 

For the full story, see: http://www.kepler.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=243

That page gives you access to the quick info, the paintings of what the planets might like, animation, etc. To get the story in a more organized way, scroll down toward the bottom and click on the link to the full NASA news release.

The gist of the discovery is that we are finding more and more planets that are roughly earth-like -- perhaps a bit bigger, not always around the same kind of star as our Sun -- but Earth-like in their temperatures and other conditions. The Kepler team said that the current discovery is just an appetizer. Many more such planets may be among the 2740 candidate planets Kepler found that they are still examining and not yet ready to confirm.