A New Planetary Neighbor

It appears we overlooked our nearest neighboring star, the red dwarf Proxima Centauri, as a potential host of planets. Until now.

A new paper published in Nature tells the story:

At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (α Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun’s closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface.

How did we miss it? It seems we have been more interested in stars like our own sun, but attitudes are changing. 

Now that the speculation has started, we can expect much more attention regarding his new world.

Maybe this would have been as easier trip for the voyagers in Kim Stanley Robinson's novel Aurora rather than Tau Ceti, which is about three times more distant. It seems to be another case of reality trumping fiction. 

Patience Pays Off: Student Discovers Planets

Michelle Kunimoto, a student at the University of British Columbia, recently discovered four new exoplanets about 3,200 light years away - one close to Mercury in size, two somewhat larger that the Earth, and a fourth closer in size to Neptune.  Ms. Kunimoto is a recent graduate from UBC where she obtained a Bachelor’s degree in physics and astronomy.

How did she do it?  A part of her research as a student, Ms. Kunimoto was studying data from the Kepler Space Telescope, which contained observations of about 150,000 stars. She noticed something odd with one of the stars but it has been missed because of the exoplanets long orbit - 637 days. While Kepler has found other exoplanets with longer orbits, it appears more planets such as these could be in the data for discovery.

In fact, it was this time last year that a high school student in England was credited with finding a Jupiter-sized exoplanet 1,000 light years away. He was looking at data collected by the Wide Angle Search for Planets (WASP) project at Keele University in England, which uses an approach similar to the Kepler Space Telescope.

So the data is out there. Now we simply need more industrious (and patient) students to sort through it. 

Image: UBC student Michelle Kunimoto (right) and astronomy professor Jaymie Matthews (left). Martin Dee/UBC

The Search for Habitable Planets Expands

It is amazing that Star Trek in the 1960s and Cosmos on the 1970s speculated about distant planets, and here we are today actually studying thousands of newly discovered planets, searching for moons around these planets, and even planning to analyze the atmospheres on the planets themselves. We may not have flying cars as promised, but we are starting to see those distant worlds we predicted which I believe is far more fascinating.

Last month, NPR had a story on the search for moons around approximately 1,000 distant planets by astronomer David Kipping at Columbia University. He believes gaseous planets similar to Jupiter and Saturn may have habitable moons where life is possible. We know our solar system has such moons, such as Europa and Enceladus, that we have yet to adequately explore for signs of life. So we have plenty of work to do here at home as well. 

Another NPR story this month discussed three nearby planets that circle a red star. Only 40 light years away, the Earth-size planets may offer a habitable environment for life. And using the Hubble Space Telescope, astronomers hope to be able to learn about the atmospheres of these planets as sunlight filters though them, while the upcoming James Webb Space Telescope will be able to provide details on the chemical composition of the atmosphere. More reasons to be excited about new space investments.

The search can only get more interesting as our technology improves and our curiosity grows. Whether in our solar system or far beyond, there is so much to study and understand. 

Above Image: Top row, left to right, is Titan, Earth's Moon, Europa, and Encelasus. Bottom row, left to right, Callisto, Charon, Ariel, and Io.

Bottom Image: Artist's rendering of the three distant planets around a red star. ESO/M. Kornmesser/Nature

Are Some Distant Planets a Mirage?

“It was thought that the reliability of the Kepler exoplanets detection was very good – between 10 and 20% of them were not planets. Our extensive spectroscopic survey, of the largest exoplanets discovered by Kepler, shows that this percentage is much higher, even above 50%. This has strong implications in our understanding of the exoplanet population in the Kepler field”.

-- Alexandre Santerne, Instituto de Astrofísica e Ciências do Espaço, discussing a new study by his team - SOPHIE velocimetry of Kepler transit candidates XVII. The physical properties of giant exoplanets within 400 days of period.  The team used SOPHIE (Spectrographe pour l’Observation des Phénomènes des Intérieurs stellaires et des Exoplanètes) to conduct its study, which is located in an observatory in france.

New NASA Video on the Hubble Space Telescope

A new NASA video titled "Oh Planet, What Art Thou?" continues the celebration of Hubble's 25th anniversary by noting how the telescope has helped to determine the composition of exoplanet atmospheres.  And while Hubble has focused on larger planets, the new James Webb Space Telescope should assist with smaller planets.  

Is the Earth the Best of All Possible Worlds?

The search for exoplanets continues, with some very interesting recent discoveries, including 11.2 billion year old planets (though the Hubble space telescope identified a 13 billion year old planet back in 2003) and planetary ring systems that is 200 times the size of Saturn's ring system.

Now Rene Heller, in a Scientific American magazine article titled "Better Than Earth," asks whether planets elsewhere may be better homes for life than our Earth.  In fact, her article notes that Earth is "poised near the inner edge of the sun's habitable zone and will become too hot to harbor liquid water in some 1.75 billion years."  This may sound like a long time, but M and K dwarf stars would have offered habitable zones that could last tens of billions of years. 

The article notes that the best time to be on Earth may have been 300 million years ago when Earth was warmer, wetter, and more oxygen-rich.  We live on a much less habitable Earth, and it may not get any better.  We would be even better on an Earth about twice the size of our current planet since it would have more inner heat, allowing the planet to last longer and benefit from a longer-lasting sun.

Hence, the galaxy offers us many options, some of which may be even better than our current situation.  And we still have 1.75 billion years to figure out how to relocate to these new worlds.  That should give us a good start. 

NOVA: A Story About Exoplanets

Earlier this month PBS's NOVA had an good program on exoplanets called Alien Planets Revealed.  You can still view the show on NOVA's website, and here is a quick summary from that same site:

It’s a golden age for planet hunters: NASA's Kepler mission has identified more than 3,500 potential planets orbiting stars beyond our Sun. Some of them, like a planet called Kepler-22b, might even be able to harbor life. How did we come upon this distant planet? Combining startling animation with input from expert astrophysicists and astrobiologists, “Alien Planets Revealed” takes viewers on a journey along with the Kepler telescope. How does the telescope look for planets? How many of these planets are like our Earth? Will any of these planets be suitable for life as we know it? Bringing the creative power of veteran animators together with the latest discoveries in planet-hunting, “Alien Planets Revealed” shows the successes of the Kepler mission, taking us to planets beyond our solar system and providing a glimpse of creatures we might one day encounter.

Sadly, the Kepler space telescope is no longer searching the heavens after a mechanical failure in May 2103, but the wealth of information that it provided between 2009 and 2013 will keep scientists busy for many years to come.  The NOVA program discusses some of the finding, including Kepler 62F, the first promising earth-like planet to be discovered (see NASA artist concept below).  Kepler 62F is about 1,200 lights years away and the program makes it clear that it would take "many million years" for us to get there with our current spacecraft.  Given NASA cannot get a budget one year out, it is unlikely this Congress will be contemplating such missions (though I still vote we send a CODEL - or congressional delegation - on the mission anyway).  

The NOVA program also discusses how about 75 percent of the stars in the galaxy are red dwarves, which means the nature of life around other suns may be quite different from ours based on the light received on the surface of the exoplanets.  Some of the ideas about flora and fauna on these red dwarf exoplanets was pretty interesting. 

Another discussion point was how our own planet's life was nothing but microbes for billions of years, and therefore this is what we should probably suspect in terms of "life" on these exoplanets if there is life at all.  And the idea that intelligent life would evolve on such exoplanets is not a given.  NOVA uses the shark as an example of non-intelligent life staying pretty much the same over 400 million years.  Hence, life may be abundant in the universe without much or any of it being intelligent or at a stage of intelligence that can communicate with us.

After all of that, the program still leaves us with the point that one out of every six stars in our galaxy has an Earth-sized planet orbiting it, which puts the number of Earth-sized planets at about 17 billion for the Milky Way.  That gives us plenty of exoplanets to explore even with all the caveats above. 

Top Image Credit:  Exoplanet Eclipse/Bill Lile, quoted from: http://www.flickr.com/photos/blile59/313907609