Sunday, April 28, 2013

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:

Sunday, April 21, 2013

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:

and with an image of a larger region around it taken with the Canada-France-Hawaii Telescope on the ground at:

Aren't they gorgeous images?


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:

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.

Wednesday, April 10, 2013

The Old Blogger Gets an Award

I'm humbled to tell you that the nation's science teachers have given me an award -- the 2013 Faraday Award for Science Communication. Given each year by the National Science Teachers' Association, this award recognizes "an individual who has inspired and elevated the public’s interest in science."

Among previous winners are Ira Flatow, the host of NPR's Science Friday show, and astronomy educator Dennis Schatz, my good friend and the Vice President of the Pacific Science Center in Seattle.

What's especially wonderful is that the award is named for Michael Faraday, the 19th-century British physicist who discovered the relationship between electricity and magnetism, and was one of the greatest communicators of science in history. That's his picture on a British bank-note. Faraday is someone I have admired for a long time (and I am not alone -- Einstein had a picture of him on the wall of his study!) Among other things, Faraday spoke out forcefully for the importance of science education in our lives and for skeptical thinking about paranormal and psychic claims. What an honor to be associated with his name.

I'm accepting the award Friday night at the annual conference of the National Science Teachers Association in Texas.

You can read the full story of the award here:

Here is a favorite quote from Faraday: “[A] lecturer should give the audience full reason to believe that all his powers have been exerted for their pleasure and instruction.”

Sunday, April 7, 2013

Making Yourself at Home on Mars

One of the most interesting results of NASA's policy to make its planetary images widely and freely available is that talented photographers around the world have combined and extended the photos to make clearer or wider views of what it's like to be on another world.

A wonderful example can be found at a site for panoramic (360-degree) images, where photographer Andrew Bodrov has made one of the most exciting space images I have yet seen:,13.54,42.5

Bodrov stitched together 407 different images from two different cameras aboard the Curiosity rover on the red planet Mars. You can see the rover itself and the "Yellowknife Bay" neighborhood that it was exploring at the time that it did the first experiment drilling into a Mars rock. The large mountain in the distance is Mt. Sharp, the rover's ultimate destination.

I encourage you to play with the image for a while. There are controls at the upper left to help you move around and your cursor also gives you control of the speed and direction with which you move through this rich image. Enjoy the details of the rover's machinery and the wide range of rock formations around the little robot visitor.