Image: Kepler-16b is the first exoplanet disc
Exquisite Exoplanetary Art
Sept. 19, 2011 --
They're alien worlds orbiting distant stars far out of reach of detailed imaging by even our most advanced telescopes. And yet, day after day, we see vivid imaginings of these extrasolar planets with the help of the most talented space artists. The definition of an extrasolar planet -- or "exoplanet" -- is simply a planetary body orbiting a star beyond our solar system, and nearly 700 of these extrasolar worlds have been discovered so far (plus hundreds more "candidate" worlds). With the help of NASA's Kepler space telescope, the ESO's High Accuracy Radial velocity Planet Searcher (HARPS), French COROT space telescope and various other advanced exoplanet-hunting observatories, we are getting very good at detecting these worlds, but to glean some of the detail, we depend on artist's interpretations of fuzzy astronomical images and spectral analyses. That's the way it will be until we build a vast telescope that can directly image an exoplanet's atmosphere or physically travel to an alien star system. So, with the flurry of recent exoplanet discoveries, Discovery News has collected a few of the dazzling pieces of art born from one of the most profound searches mankind has ever carried out: the search for alien worlds orbiting other stars; a journey that may ultimately turn up a true "Earth-like" world.
Image: An exoplanet passes in front of (or "t
As an exoplanet passes in front of its star as viewed from Earth, a very slight dip in starlight brightness is detected. Observatories such as NASA's Kepler space telescope use this "transit method" to great effect, constantly detecting new worlds.
Some exoplanets orbit close to their parent stars. Due to their close proximity and generally large size, worlds known as "hot Jupiters" are easier to spot than their smaller, more distant-orbiting cousins.
Image: An artist's impression of Gliese 581d,
The primary thrust of exoplanet hunting is to find small, rocky worlds that orbit within their stars' "habitable zones." The habitable zone, also known as the "Goldilocks zone," is the region surrounding a star that is neither too hot nor too cold. At this sweet spot, liquid water may exist on the exoplanet's surface. Where there's water, there's the potential for life.
Credit: David A. Aguilar (CfA)
Usually, exoplanet hunters look for the slight dimming of a star or a star's "wobble" to detect the presence of an exoplanet. However, in the case of Kepler-19c, its presence has been detected by analyzing its gravitational pull on another exoplanet, Kepler-19b. Kepler-19c is therefore the Phantom Menace of the exoplanet world.
Image: A cool world some distance from its st
The habitable zone seems to be the pinnacle of extraterrestrial living. If you're an alien with similar needs to life on Earth, then you'll need liquid water. If your planet exists outside your star's habitable zone, well, you're in trouble. Either your world will be frozen like a block of ice, or boiling like a kettle. But say if your world had the ability to extend your star's habitable zone? There may be some atmospheric factors that might keep water in a comfy liquid state. Even better, if you like deserts, a dry world could even be oddly beneficial.
Image: A "hot Jupiter" and its two hypothetic
Planets with a global magnetic field, like Earth, have some dazzling interactions with the winds emanating from their stars. The high-energy particles bombard the planet's atmosphere after being channeled by the magnetism. A wonderful auroral lightshow ensues. But say if there's an exoplanet, with a magnetosphere, orbiting really close to its star? Well, stand back! The entire world would become engulfed in a dancing show, 100-1000 times brighter than anything we see on Earth.
Credit: Adrian Mann, <a href="http://www.bisb
"Candidate" exoplanets are often mentioned, especially when talking about detections by the Kepler space telescope. But what does this mean? As a world passes in front of its star, slightly dimming the starlight, this isn't considered a "confirmed" exoplanet detection. To make sure that signal is real, more orbital passes of the exoplanet need to be logged before a bona fide discovery can be announced. Until then, these preliminary detections are called exoplanet candidates.
Image: An exoplanet being destroyed by X-rays
Angry Suns, Naked Planets
Exoplanets come in all sizes and all states of chaos. Some might have wonky orbits, others might be getting naked. Other times, they're simply being ripped apart by X-rays blasted from their parent star. Bummer.
Image: Artist's impression shows HD 85512b, a
Super-Earths get a lot of press. Mainly because "Earth" is mentioned. Sadly, most of these worlds are likely completely different to anything we'd call "Earth." And you can forget calling the vast majority of them "Earth-like." It's simply a size thing -- they're bigger than Earth, yet a lot smaller than Jupiter, hence their name, "super-Earth." Easy.
Credit: Adrian Mann, <a href="http://www.bisb
For now, we have to make do with artist's renditions of exoplanets for us to visualize how they may look in their alien star systems. However, plans are afoot to send an unmanned probe to an interstellar destination. Although these plans may be several decades off, seeing close-up photographs of these truly alien worlds will be well worth the wait.
The International Astronomical Union (IAU) — the official body that governs the designations of all celestial bodies — in their capacity of purveyors of all things “official” has deemed attempts at crowdsourcing names for exoplanets illegitimate.
“In the light of recent events, where the possibility of buying the rights to name exoplanets has been advertised, the International Astronomical Union (IAU) wishes to inform the public that such schemes have no bearing on the official naming process,” writes Thierry Montmerle, General Secretary of the IAU in Paris, France.
Although the “schemes” are not specifically named, the most popular US-based “exoplanet naming” group Uwingu appears to be the target of today’s IAU statement. Set up by Alan Stern, planetary scientist and principal investigator for NASA’s Pluto New Horizons mission, Uwingu encourages the public to nominate and vote (for a fee) on names for the slew of exoplanets steadily being discovered.
The rationale is that through this crowdfunding campaign, the public becomes more engaged with exoplanetary science (and astronomy as a whole) and the proceeds from the naming process will go toward subsidizing science research.
This IAU response probably won’t come as a surprise to many involved in the project.
In recent years, the IAU became infamous for “demoting” Pluto to a dwarf planet in the wake of the 2005 discovery of the Kuiper belt object Eris. The 2006 ruling caused widespread controversy and a public outcry. The IAU saw the definition of a “planet” as being outdated and, in response to the increasing number of large rocky bodies being discovered in the Kuiper Belt and beyond, felt a true planet needs to meet certain criteria. Pluto failed on one “planetary standard”: its gravitational clout isn’t strong enough to clear its own orbit. Critics of this decision cried foul, pointing out that if Earth was transported to Pluto’s cluttered orbit, it wouldn’t be defined as a planet either. Still, the IAU ruling was final.
Today’s statement underlines the IAU’s jurisdiction, not only in the field of solar system planet naming, but also in the extrasolar planet arena.
“Recently, an organisation has invited the public to purchase both nomination proposals for exoplanets, and rights to vote for the suggested names,” explains Montmerle. “In return, the purchaser receives a certificate commemorating the validity and credibility of the nomination.
“Such certificates are misleading, as these campaigns have no bearing on the official naming process — they will not lead to an officially-recognised exoplanet name, despite the price paid or the number of votes accrued.”
The astronomy world is no stranger to “name a star” or “buy lunar real estate” scams that use the above process for personal profit and the IAU “dissociates itself entirely from the commercial practice of selling names of planets, stars or or even ‘real estate’ on other planets or moons.” Uwingu, however, uses the “name an exoplanet” idea to generate funds for public outreach and science grants. Even so, the IAU seems to view such attempts as nothing more than a variation on “name a star.”
“While exoplanet names such as 16 Cygni Bb or HD 41004 Ab may seem boring when considering the names of planets in our own Solar System, the vast number of objects in our Universe — galaxies, stars, and planets to name just a few — means that a clear and systematic system for naming these objects is vital. Any naming system is a scientific issue that must also work across different languages and cultures in order to support collaborative worldwide research and avoid confusion.” — IAU statement
Indeed, this presents a problem for Uwingu. Although the crowdsourcing organization will likely continue, getting such a forthright response from the official international astronomical naming body will be a disappointment. It leaves little scope for the Uwingu naming process to become official.
Recently, a campaign to name Alpha Centauri Bb generated a huge amount of interest, proving Uwingu, even though it’s only in its first few months of operation, is fulfilling its outreach goals. But the IAU has deemed the project illegitimate (in an official naming sense), a factor that will likely have a heavy impact on the project’s future.
Until then, the IAU doesn’t appear to be budging.
Image: An exoplanet as seen from its moon. Credit: IAU/L. Calçada