systemic

Seeing in the Dark1
greg posted in non-technical posts on September 19th, 2007

This evening (Sept. 19th) the US Public Broadcasting Service is running a documentary on amateur astronomy which will include a section on extrasolar planets. The production is called Seeing in the Dark and it looks like it should be a very interesting and well done program.

Featured in the film are my friends and collaborators Ron Bissinger and Debra Fischer. Ron (whose day job is CEO of Alpha Innotech) has been a core member of Transitsearch.org from the beginning, and has consistently obtained great observations of transiting planets. Debra (an astronomy professor at SFSU) has, among her many accomplishments, discovered literally scores of extrasolar planets using the radial velocity technique. Both Ron and Debra’s work has been the focus of many past posts on this website.

So tonight, set your telescopes to acquire HD 185269, enable the robotic photometric observing mode, and sit down in front of the tube with a bowl of popcorn!

Discover a planet3
greg posted in exoplanet detection, non-technical posts on September 11th, 2007

Image Source.

My tight 30-minute layover in Denver turned into an eight-hour delay yesterday when a solenoid somewhere in our Boeing 777 malfunctioned just prior to pushback, giving me an unexpected opportunity to attempt to catch up on all the work that’s been piling up.

After 6 hours of tapping on the laptop, I’d exhausted my effectiveness, so I bought glossy magazines from the airport newstand. In the latest issue of Portfolio from Conde Nast, you can read an in-depth Vanity Fair style puff piece on ex-Tyco CFO Mark Swartz’s life in the Big House, and, in one of the advertisements, you’re encouraged to use a Visa “Signature” card to charge up some of the finer experiences in life. Quite to my surprise, #17 on a list that includes “See the Tony Awards live”, and “Test-drive a supercar”, is “Discover a planet”.

Now regular visitors to oklo.org all know that you can get your planet-discovery experience right here on the systemic backend without ever having to reach for your wallet. In fact, just yesterday, we learned from Gregory’s latest preprint on astro-ph that Eric Diaz (and a number of other systemic users) appear to have made the first characterizations of the most statistically probable planetary system fits to the HD 11964 radial velocity data set.

The HD 11964 data set was published by Butler et al. (2006). Two planets are already known to orbit this star. HD11964 b has roughly 1/3rd of a Saturn mass and a ~38-day orbit, whereas HD 11964 c is a sub-Jovian mass planet on a ~2110-day orbit. There’s a wide dynamically stable gap between the two planets, making this system a fertile hunting ground for additional companions.

Gregory does an extensive statistical analysis and argues that there’s strong evidence for a sub-Saturn mass planet on a year-long orbit. Eric Diaz’s version of this planet shows up in the fit that he submitted to systemic back in July 2007:

Eric also suggests the presence of a 12.4-day planet in the system. The Gregory analysis suggests that this planet is not statistically significant, but I’m going to add it to the transitsearch.org unpublished candidates list. There’s certainly no reason not to have a look-see if anyone has unused photometric capability.

eclipse (a transit by any other name)2
greg posted in non-technical posts on August 28th, 2007

Image Source: APOD.

Last night, the alarm went off at 2:45 AM, just prior to the start of the full lunar eclipse. Remarkably, the fog had stayed away. The air was slightly warm, and the town was absolutely quiet. The shadow of the Earth was covering nearly the entire lunar surface, with just a small oblique portion of the lower right hemisphere still in sunlight. A few minutes later, the whole moon was glowing a dull orange-red against the easily visible stars of the ecliptic. It was creepy, weird. Definitely worth getting out of bed for.

The Sun and the Moon occupy nearly the same angular size in Earth’s sky. This means that to good approximation, the patch of sky covered by the moon during a central lunar eclipse contains stars that can see the Earth in transit across the face of the Sun.

And during a lunar eclipse, they see a double transit.

The famous “tooth” in the HST light curve for TrES-1 is generally attributed to the planet passing over starspots, but for those who prefer not to shave with Occam’s razor, it can be equally well modeled by a double transit.

Last night, during the eclipse, the Moon (at RA 22h 26 min, Dec= -09 deg 57 min) was only a few degrees away from the planet bearing stars GJ 876, GJ 849, HD 21707, and HD 219449.

Barred Spiral4
greg posted in non-technical posts, worlds on July 26th, 2007

Image Source.

I’d never really seen the Milky Way until I saw it on a perfectly clear and moonless July night from a spot just below the Arc Dome in central Nevada. It spills a swath of patchy luminosity that seems to split the sky in half; a barred spiral galaxy, seen edge-on, and from within. One hundred billion intensely glowing stars, like sand grain jewels, each separated by miles. The photo above (taken by Steve Jurvetson last weekend from the Black Rock Desert in Nevada) reminded me of that experience.

The dark sky applet shows that the interior of Nevada (away from Las Vegas!) contains many of the least light-polluted areas of the United States.

Under a totally dark sky, you can distinctly see the star clouds in the foreground of the galactic center. It’s eerie to think that the 3-million solar mass black hole lurking in the center of the galaxy is just to the right of the bright luminosity of Baade’s Window near the boundary between Sagittarius and Scorpius.

The photo also shows Jupiter within a few degrees of Antares — a nice illustration of the fact that Jupiter appears slightly brighter than the brightest stars.

Newton used this similarity in apparent brightness to get the first real estimate of the staggering distances to the stars. He assumed that the stars are similar in absolute brightness to the sun, and he assumed that Jupiter (whose distance and angular size were known to him) is a perfect reflector of sunlight. This method underestimates the distance to Sirius by more than a factor of five, but it does a fairly reasonable job for Alpha Centauri.

blue moon1
greg posted in non-technical posts on May 31st, 2007

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I was scrambling to prepare for my class this morning when the telephone rang. It was a reporter from a local newspaper.

“I was referred to you as someone who could tell me about the blue moon.”

For a moment, I wasn’t quite sure what she was talking about. “Oh, uh, yeah? You mean there’s a blue moon coming up?”

“Well absolutely!” she said, “We were wondering if astronomers are planning anything special in connection with this blue moon.”

She seemed rather disappointed to learn that there are no special plans in the works and that the blue moon is eliciting little to no excitement among astronomers. But nevertheless, she’d been put on the story, and she had to write something. I glanced nervously at my watch. Class was looming up alarmingly soon, and my ability to explain radiative transfer in planetary atmospheres wasn’t yet all it could be.

“Well, would you say that most astronomers are even aware that we’re having a blue moon tomorrow?”

The slight tint of exasperation in her voice made it clear that this one could be a lose-lose question. Indeed, the majority of professional astronomers are probably blissfully unaware that tomorrow is a blue moon in the Western Hemisphere (based on both the calendar and the Farmer’s Almanac definitions). But if I told her that, then I could imagine the slant that the story might take — callous astronomers out of touch in their overfunded overcomputerized observatories. On the other hand, if I professed excitement about the blue moon, I might come off as a bit of a wacko, someone who gets off the bus one stop short of astrology…

“Well, my guess is that most astronomers teaching introductory astronomy classes are certainly aware that tomorrow is a blue moon. It’s a good way to tie the ebb and flow of our Gregorian calender into the cycle of lunar phases. It brings a bit of immediacy and, uh, color to a lecture on the phases of the moon.”

Oklo.org’s latest recommendation is that you take off from work early tomorrow and have a few beers. It’s a good way to get ready for the next ‘606 day, which occurs at on Aug. 6th 2007 at 21:26 (UT).

The Gliese 581 system1
greg posted in non-technical posts, worlds on April 26th, 2007

I’m still really jazzed that the systemic users detected Gl 581 c prior to its discovery announcement.

A dramatic ESO press release “Artist’s impression” of the Gl 581 system is all over the web today. It shows a planet that appears quite dry, clearly drawing on a model of in-situ formation from silicates and iron. In all likelihood, however, the planet migrated from beyond the snowline in Gl 581’s protostellar disk. It likely contains at least an Earth’s mass worth of water, and the view from space would show the upper layers of a deep and stormy atmosphere. Jonathan Langton is running hydrodynamical simulations to try to get a sense of what the weather is like on this world, and we’re hoping to have an animation up very shortly. (See this brief description of yesterday’s splash image).

Image Source.

One of my pet peeves is that it’s possible to produce far more accurate and photo-realistic press release images of extrasolar planets than is usually done. Artist’s impressions generally veer toward being luxuriously long on depicting what we don’t know and rudely short when it comes to presenting what we do know.

At the JPL Cassini/Huygens website, there is a trove of photos taken by the orbiter showing Saturn and its moons from different vantages and illumination conditions. The photos below were taken from a location near the ring plane, and show Rhea and Enceladus. The two pictures were taken one minute apart as Enceladus (314 miles in diameter) is occulted by the larger Rhea (949 miles across) as seen from the spacecraft.

This sequence of photos makes the most of the kinds of information that we do know about extrasolar planets, namely the system geometry, the relative sizes, the orbital dynamics, and the illumination. Note how the night side of Enceladus is eerily lit by the unseen Saturn. These particular photos, furthermore, are effortlessly discrete with respect to what we don’t know about extrasolar planets, namely the geological details of the surfaces. In the absence of concrete information, the surface is perhaps better left either to the mind’s eye or to the moment when we get the real image. In Cassini’s glorious up-close view, Enceladus was revealed to be far more bizarre and interesting than anyone had imagined:

The lighting in the Gl 581 press release image is pretty weird. We’re looking straight at the parent star, and yet planet “c” is seen in quarter phase, illuminated by a source of white light placed to the right of the scene. The star, however, is thought to be single.

The dynamic range of illumination in the scene is way off as well. If we’re looking straight at a star, then the field of view is completely flooded, saturated with light, and replete with lens flares. Planets are always lost in the glare if you’re looking straight at a star. Since any view of a star is seen through an optical system, I think it should be possible to achieve a better sense of optical dynamical range by correctly applying lens flares. Over the next year, we’ll be looking into this in much more depth.

Image Source.

This website has an interesting discussion of how to correctly render the colors of stars. Dynamic range aside, and assuming that the star is a 3000K blackbody radiator (which isn’t quite right, but is a reasonably good approximation) the color should be a lighter shade of orange. As drawn, the color is more appropriate to the night-side glow of a hot Jupiter.

What about the perspective in the scene? At first glance, it looks like Gl 581 “b” might have been drawn a little too large. Using the information in table 1 of the Udry et al. preprint, and adopting a 1.7 Earth-diameter size for “c”, a Neptune-size for “b”, and 0.3 solar diameters for Gl 581 itself, we can draw the orbits and sizes of the planets to scale and almost have it fit correctly in an image that fits on the blog. (You may want to make your browser window wider):

In reality, because of pixelation, the tiny dots showing the planets are a bit larger than they should be. Ellipses are circles seen from an angle, so by applying a 1-dimensional re-scale with Adobe Illustrator, we can view the system to scale from a long distance away:

When I’m looking at the ESO press release image on my computer screen, the planet measures 7.5 cm across, and is located 45 cm from my eye. It subtends an angle of 9.5 degrees at the vantage from which its being viewed. The point of view is thus located 11 planetary radii above the surface of the planet, and drawn to scale, the geometry in the image looks like this:

As viewed from the skies of planet “c”, planet “b” subtends an angle of 36 arc minutes, and remarkably, would appear just slightly larger than the Moon appears from Earth. The parent star, on the other hand would subtend 2.3 degrees of the sky, which is about ~4.6 times larger than the Sun appears in our sky. (Given that Gl 581 “c” is in a habitable orbit, and given that the star is a red dwarf, it’s absolutely necessary to have the star fill more of the sky.) With this information, we can draw the correct angular sizes of the star and the planet “b” as seen from the vantage of the drawing. The planet “b” should be somewhat smaller than drawn, and the star should be somewhat larger. On the balance, however, the angular sizes aren’t that far away from being correct.

Walker Lake2
greg posted in non-technical posts, worlds on April 11th, 2007

Image Source

It’s hard to get a more profound sense of physical remoteness and isolation in the United States than to drive east from Walker Lake, Nevada as the Sun sinks below the western horizon. It’s like Mars.

On a transcontinental flight last month, I had a window seat away from the wing. The sky was clear over Nevada, and the sun angle was low. It was an ideal situation for high-resolution imaging of a habitable terrestrial planet. The airplane view provides an interesting link between the experience of driving across the landscape and examining the satellite photos. The area just east of Walker Lake imparts an impression of a planet that’s very different from the global idea of the “pale blue dot.” The lake itself is salty, alkaline.

Source: Google Maps

The satellite and aerial photographs show that Walker Lake seems to be an evaporating remnant of what was once a much larger body of water.

Four billion years ago, Gusev crater on Mars probably looked very similar, with a sour central lake receeding with bathtub-ring clockwork.

Image: NASA

On Mars, there are only a few spots where a high-level of zoom will reveal artificial features:

Image Source

On Earth, in the region to the East of Walker Lake, there’s very little that can’t be ascribed to natural processes. This smooth black curve seems to be a wave cut bench of the vanished shoreline:

This feature, however, would be more challenging for a planetary geologist to explain. It’s obviously younger than the channels that it cuts across. Perhaps it’s fresh material that welled up from a crack in the Earth’s crust? There are volcanos dotted across the Basin and Range province.

Just south of the region shown in the splash image for this post, there are some extremely strange landforms…

And as is often the case in planetary exploration, when one wants to see even more detail,

Impact!5
greg posted in Uncategorized, non-technical posts on March 7th, 2007

Image Source.

The news out of the Planetary Defense Conference is that NASA has the ability to locate all the potentially dangerous asteroids in our solar system by the year 2020, but that the cash to carry out the project is not currently forthcoming.

CNN and many other news outlets carried the story, along with a dramatic artist’s rendition of an asteroid striking the Earth.

That’s a rather large asteroid.

Measuring the circumscribed circles, it appears that the impacting body is 1/10th the Earth’s diameter, or approximately 600 km in radius. A bolide of this magnitude would currently rank as the ~25th largest object in the solar system, larger than Uranus’s moon Umbriel (584 km radius), smaller than Saturn’s moon Iapetus (736 km in radius), and nearly exactly the same size as Pluto’s moon Charon (606 km in radius). Ceres, the largest object in the main asteroid belt, by contrast, has a radius of ~475 km.

Based on the location of the late-afternoon catastrophe relative to the day-night terminator, the impactor seems to have had an orbit that was highly inclined relative to the solar system’s angular momentum plane. Perhaps it was undergoing Jupiter-driven Kozai oscillations prior to striking the Earth.

The last impact of the magnitude shown in the illustration was probably the Moon-forming impact ~4.4 Billion years ago, in which a Mars-sized body struck the Earth. Kevin Zahnle of the NASA Ames Research Center has estimated the distribution of giant impacts after the Moon-forming event. It’s likely that the largest strikes were by bodies with roughly half the radius of the object shown in the above picture.

The consequences of even a 300 km object hitting the Earth are severe. Such an impact is energetic enough to entirely vaporize the Earth’s oceans and create a temporary rock-vapor atmosphere with a surface pressure of ~100 bars. For a period of several months to a few years, the Earth would radiate with a temperature of ~2000 Kelvin — hot enough to glow brightly in the visible region of the spectrum. And depressingly, our planet would be fully sterilized by the event.

This week’s crop4
greg posted in exoplanet detection, non-technical posts, worlds on March 6th, 2007

Image Source.

The year 2007 is off to a reasonably good start. Three more planets were announced by the Geneva Planet Search team at a conference in Chile, bringing the total planet crop for ‘07 up to seven.

The rate of planet discovery, however, has definitely leveled off. For the past four years, the detection rate has remained fixed at 26 new planets per year. The low-hanging fruit — the 51 Pegs, the 47 Ursae Majorii, the Upsilon Andromedaes — have all been harvested from the bright nearby stars, and increasingly extractive methods are being brought to bear. Transits are starting to contribute significantly to the overall detection rate. Radial velocity is pushing to planets with progressively lower masses. Surveys such as N2K are rapidly screening metal-rich stars that have high a-priori probabilities for harboring readily detectable planets. The neccessity of finding more planets is driving up the average metallicity of the known planet-bearing stars:

The three new planets, HD 100777b, HD 190647b, and HD 221287b are quite ordinary as far as extrasolar planets go. They all have masses somewhat greater than Jupiter, and they all take more than a year to orbit their parent stars. Their discovery seems not to have registered with the news media:

HD 100777 b, however, is actually deserving of some attention. Its orbital period of 383.7 days places it squarely in the habitable zone of its parent star. The eccentricity, e=0.36, is fairly high, and likely leads to interesting seasonal effects in the atmosphere of the planet.

HD 100777 b lies a regime where we expect to see white water clouds forming in the visible atmosphere. The planet is probably very reflective in the optical region of the spectrum (quite unlike the hot Jupiters, which are likely cloud-free, and which are known to absorb almost all of the starlight that strikes them). Convection of interior heat to the surface of HD 100777b is almost certainly driving collossal thunderstorms, and the atmospheric disturbances created by the thunderstorms likely feed giant vortical storms similar to Jupiter’s great red spot.

It’s also possible that the atmosphere is much clearer in regions where air wrung dry by rainfall is downwelling. This phenomenon occurs on Jupiter, where highly transparent patches occur over several percent of the Jovian surface:

Image Source.

The Galileo entry probe went right into one of these regions, and sampled very dry air. On HD 100777, the regions of high atmospheric transparency will probably preferentially absorb red and green light (as a result of Rayleigh scattering of incoming photons). The surface, then, in the vicinity of a downwelling region may look something like this:

flyby1
greg posted in non-technical posts, worlds on March 1st, 2007

Image: NASA New Horizons Spacecraft (false color by oklo).

One day, one hour, and nine minutes ago, the New Horizons spacecraft sailed flawlessly through its closest approach to Jupiter. A day later, Jupiter still looms large in New Horizon’s field of view, with an angular size more than five times greater than the size of the full moon in our sky.

Jupiter, during its 4.5 billion year history, has been visited by at least seven other probes. Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Ulysses, Galileo, and Cassini have all successfully made the journey. This latest encounter was buried beneath the news of a 500-point drop in the Dow Jones Industrial Average. The flyby, in fact, hasn’t even made it onto the Astronomy Picture of the Day!

A decade ago, many of the metal atoms in the New Horizons spacecraft were still buried in the Earth’s crust. A bit more than a year ago, the assembled spacecraft was flown, in a sealed pressurized container, to Cape Canaveral for launch. All through the past several weeks, it’s been taking pictures of the Jovian system. Most of the data will be radioed back to Earth over the coming months. The image above was taken on Monday, and shows a Von Karman vortex sheet trailing away from the Little Red Spot, currently the second-largest storm in the Solar System.

In a sense, the Jupiter encounter was mostly utilitarian. It boosted the spacecraft’s heliocentric velocity (at the expense of Jupiter’s orbital energy) and cut down the travel time to Pluto.

The next scheduled mission to Jupiter is Juno, the Jupiter Polar Orbiter, which is scheduled to arrive at the Jovian system in 2016.

The exoplanet prediction market1
greg posted in exoplanet detection, non-technical posts, systemic faq, worlds on February 20th, 2007

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At first glance, the market capitalization of the Chicago Board Options Exchange, and the list of astronomers active in the field of extrasolar planets would appear to have nothing to do with one another. These two disparate entities are connected, however, by the fact that they’ve both undergone explosive growth over the past decade, and both are continuing to grow. They signify highly significant societal trends.

I think it’s safe to predict that in 25 years, the market for financial derivatives, and the level of economic activity associated with exoplanets will both be far larger than they are now. It’s interesting to ask, will there be an unanticipated co-mingling between the two? And if so, how will it occur?

One very realistic possibility is the development of an exoplanet prediction market, in which securities are issued based on particular fundamental questions involving the distribution of planets in the galaxy. Imagine, for example, that you’re an astronomer planning to devote a large chunk of your career to an all-or-nothing attempt to characterize the terrestrial planet system orbiting Alpha Centauri B. In the presence of a liquid, well-regulated exoplanet prediction market, you could literally (and figuratively) hedge your investment of effort by taking out a short position on a security that pays out on demonstration of an Earth-mass planet orbiting any of the three stars in Alpha Centauri.

Prediction markets have been adopted in a very wide range of contexts, ranging from opening weekend grosses for big-budget movies, to forecasts of printer sales, to the results of presidential elections. A highly readable overview of these markets by Justin Wolfers (who was featured last week in the New York Times) and Eric Zitzewitz of the University of Pennsylvania is available here as a .pdf file. The ideosphere site contains a wide variety of markets (trading in synthetic currency) and includes securities directly relevant big-picture questions in physics, astronomy and space exploration. Here’s the price chart for the Xlif claim,

which pays out a lump-sum of 100 currency units if the following claim is found to be true:

Evidence of Extraterrestrial Life, fossils, or remains will be found by 12/31/2050. Dead or extinct extraterrestrial Life counts, but contamination by human spacecraft doesn’t count. (Life engineered or created by humans doesn’t count.) The Life must have been at least 10,000 miles from the surface of the Earth. If Earth bacteria have somehow got to another planet and thrived, it counts, as long as the transportation wasn’t by human space activities.

It’s very interesting to compare the bullish current Xlif price quote of 72 with the far more bearish sentiment on Xlif2, which is currently trading at an all-time low of 17,

and which pays out if “extraterrestrial intelligent life is found prior to 2050″, and more specifically,

Terrestrial-origin entities (e.g. colonists, biological constructs, computational constructs) whose predecessors left earth after 1900 do not satisfy this claim. If the intelligence of the ET is not obvious, the primary judging criteria will be either a significant level of technological sophistication (e.g. radio transmitting capability) or conceptual abstraction (e.g. basic mathematical ability). Radio signals received or similar tell-tale signs of intelligence (e.g. archeological discoveries) detected and accepted by scientific consensus as originating from intelligent extraterrestrials would satisfy the claim even if not completely understood by the claim judging date.

Recently, open-source software has been released that makes it straightforward to set up a prediction market. We’ll soon have the world’s first exoplanet stock market up and running right here at oklo.org. In the meantime, feel free to submit specific claims (in the comments section for this post) that might lend themselves to securitization…

glow0
greg posted in non-technical posts, worlds on February 12th, 2007

Image Source.

Saturn reached opposition yesterday, marking the moment in our yearly orbit when the Earth draws closest to the massive ringed giant. At midnight, Saturn is currently the only planet visible in the sky. It’s an odd feeling to stare at the bright unresolved spot of light that encompasses the planet, the rings, and the moons into a tiny golden point, and to know that Cassini, our robot emissary, is actually out there, almost a billion miles away, taking photograph after photograph, and radioing them back to a mere mouse click away.

Schematic image of the solar system on 2/11/2007 created at Solar System Live.

Saturn and its rings are good reflectors of light, but nevertheless, in the vicinity of the planet, the glare is far from overwhelming. The ambient light levels are only a bit more than 1% that of a bright summer day on Earth. It would be easy to stare at the crisply defined terminator marking the day-night boundary on the planet and the arcs of black shadow cast by the rings. On the Cassini website, there are many views that show the planet as it would appear to human eyes.

Image Source.

Cassini also has the ability to photograph in the infrared. The following false-color photograph shows visible and infrared images of the planet superimposed. In the infrared, Saturn glows with interior heat — still welling up from the planet’s formation — that illuminates the night from within.

Image Source.

The picture above is not a bad approximation of what a younger more massive planet would look like to the naked eye. 2M1207 b, for example, which seems to have a mass about five times that of Jupiter, is in a 1700-year orbit around a young 25-Jupiter mass brown dwarf. At 1250 Kelvin, 2M1207b is still warm enough to be self-luminous in the visible region of the spectrum. It is also slightly illuminated by the light of its companion (whose ~2500K surface is intrinsically 100 times more luminous.) Methane absorption and Rayleigh scattering of incident light in 2M1207 b’s atmosphere likely give the weak crescent a bluish-green hue.

Image Source.

mp3s of the spheres0
greg posted in non-technical posts, systemic faq on January 18th, 2007

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New users are still streaming into oklo.org. If you’re a first-time visitor, welcome aboard. You’ll find information that you need to get started in this post from several days ago.

The EZ-2-install downloadable systemic console is the primary software tool that we provide for analyzing data from extrasolar planetary systems. The tutorials 1,2, and 3 are the best way to learn how to use the console. Over the past few months, we’ve been adding a range of new capabilities that go beyond the features described in the tutorials and which improve the overall utility of the software. We’ll be explaining how these new features work in upcoming posts, and for our black-belt users, we’re also putting the finishing touches on a comprehensive technical manual.

When we designed the console, our main goals were to produce a scientifically valuable tool, while at the same time make something that’s fun and easy to use. Early on, we settled on the analogy with a sound mixing board, in which different input signals (planets) are combined to make a composite signal.

We’ve pushed the audio analogy further by adding a “sonify” button to the console. When sonification is activated, you can turn the stellar radial velocity curve into an actual audible waveform. If you create a system with several or more planets, these waveforms can develop some very bizarre sounds. From a practical standpoint, one can often tell whether a planetary system is stable by listening to the corresponding audio signal. Alternately, the console can be used as a nonlinear digital synthesizer to create a very wide variety of tones.

Here are links (one, and two) to past posts that discuss the sonification button in more detail. If you come up with some useful sounds, then by all means upload the corresponding planetary configurations to the systemic back-end.

Armchair Planet Hunting4
greg posted in non-technical posts, systemic faq on January 15th, 2007

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The Associated Press just published an article on how the Internet has facilitated an increasing number of collaborations between amateur and professional astronomers. The systemic project is one focus of the AP piece, and we’re seeing a jump in traffic as a result. If you are a first-time visitor to the site, welcome aboard!

There are several ways that you can use and participate in systemic. Our project home page is a weblog (updated fairly frequently) that gives an insider’s perspective on the latest developments and discoveries in the fast-moving fields of extrasolar planets and solar-system exploration. We write for a target audience of non-astronomers who are interested in astronomy. To get a flavor for the blog, keep reading the posts below, or have a look at a few of our past articles, such as our take on last Summer’s big “is Pluto a planet debate”, our exploration of what planets and galaxies really look like, or our series [1, 2, 3, 4] on the feasibility of detecting habitable terrestrial planets in the Alpha Centauri System.

You should see a set of links just to your right:

These links give you information that you can use to start participating in the actual discovery and characterization of extrasolar planets. (Despite the fact that we’re rocket scientists, we’ve been unable to consistently sweet-talk Microsoft IE into correctly displaying our site. On some versions of IE, you may have to scroll all the way down to the bottom of this page to see the links). The Downloadable Systemic Console is our Java-based software package that allows you to work with extrasolar planet data. The Systemic Backend is a collaborative environment that has the look and functionality of a social networking site. Registration and participation are free. The nearest well-characterized extrasolar planets (GJ 876 b, c and d) are 14.65 light years away, and so the news of useful modern innovations such as pop-ups and spyware hasn’t had time to propagate to those far-distant worlds. Hence the systemic backend is completely free of annoying ads!

One final note: there are two separate channels for registration on systemic. The first, accessed through the “login” tab on the site header above, is part of the Wordpress package that runs the blog. Registration on the blog allows you to comment on our frontend posts. The second, accessed through the “backend” tab on the site header or the link to the right, gives you access to the collaborative php-based environment that constitutes the systemic backend. You can register for either or both, and you don’t need to give your real name or any real-world identifying information other than an e-mail address.

Tune in regularly for more news and updates.