Space & Innovation

Two Exocomet Families Found Around Baby Star System

Scientists have found two families of comets in the developing Beta Pictoris star system, located about 64 million light-years from Earth, including one group that appears to be remnants of a smashed-up protoplanet.

Scientists have found two families of comets in the developing Beta Pictoris star system, located about 64 million light-years from Earth, including one group that appears to be remnants of a smashed-up protoplanet.

The discovery bolsters our theoretical understanding of the violent processes that led to the formation of Earth and the other terrestrial planets in the solar system.

PHOTOS: Exquisite Exoplanetary Art

"If you look back at the solar system when it was only 22 million years old, you might have seen phenomena that's a like more like what's happening in Beta Pic," astrophysicist Aki Roberge, with NASA Goddard Space Flight Center, Greenbelt, Md., told Discovery News.

"Rocky planets like the Earth, or any kind of solid planet, are built up out of comets and asteroids. It's the collisions of those bodies that build up the planets in the first place," she said.

Astronomers found the exocomets by analyzing eight years of archived data collected by the HARPS instrument on ESA's 3.6-meter telescope at La Silla Observatory in Chile. They were focusing on small, evaporating bodies that passed across the face of their parent star, relative to the telescope's line of sight.

ANALYSIS: Dust to Dust: The Death of an Exoplanet

"Our results show that the evaporating bodies observed for decades in the Beta Pictoris system are analogous to the comets in our own solar system," astronomer Flavien Kiefer, with the French National Centre for Scientific Research in Paris, and colleagues wrote in an article published in this week's Nature.

One group of comets, designated population S, appears to be gravitationally tied to massive planet, possibly Beta Pictoris b, which circles its parent star about as far as Saturn orbits the sun. Astronomers strongly suspect a second gas giant planet exists beyond Beta Pic b.

NEWS: The Exoplanet With a Comet-Like Tail

The other comet family, population D, produces more gas than the S comets, indicating they are either physically larger or fresher, with more exposed surface ice. They also are farther away from Beta Pic than the S comets. The D comets also have similar orbits, which is consist with the idea that they are fragments of a larger, icy planetary body that recently broke apart.

Additional analysis may reveal how recently that collision happened, Roberge said.

Observations of Beta Pictoris b, a massive exoplanet that orbits the star Beta Pictoris about as far as Saturn orbits the sun. | ESO

This artist’s impression shows exocomets orbiting the star Beta Pictoris. Astronomers analysing observations of nearly 500 individual comets made with the HARPS instrument at ESO’s La Silla Observatory have discovered two families of exocomets around the young star.

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.

The Transit

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.

Hot Jupiters

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.

Habitable Worlds

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.

A Phantom

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.

Keeping Warm

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.

Crazy Aurorae

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.

The "Candidates"

"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.

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.

Super-Earths

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.

Let's Go!

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.