Exoplanet Count Tops 700

An artist's impression of a lone exoplanet transiting its parent star. There are now 700 confirmed alien worlds orbiting other stars (ESO)

An artist's impression of a lone exoplanet transiting its parent star. There are now 700 confirmed alien worlds orbiting other stars (ESO)

On Friday, the Extrasolar Planets Encyclopedia registered more than 700 confirmed exoplanets. Although this is an amazing milestone, it won’t be long until the “first thousand” are confirmed.

There are now more than 700 confirmed exoplanets in the database. The latest addition is the planet HD 100655 b.
— announced via the Exoplanet iPhone app

Only two months ago, the encyclopedia — administered by astrobiologist Jean Schneider of the Paris-Meudon Observatory — registered 600 confirmed alien worlds. Since then, there has been a slew of announcements including the addition of a batch of 50 exoplanets by the European Southern Observatory’s (ESO) High Accuracy Radial velocity Planet Searcher (or HARPS) in September.

The first exoplanet was discovered orbiting a Main Sequence star in 1995, and the rate of exoplanet detections has been accelerating ever since.

It is worth noting that hundreds more candidate exoplanet detections have been made, many of which have been spotted by NASA’s Kepler space telescope. Kepler is staring at the same patch of sky, waiting for alien worlds to cross the line of sight between their parent star and Earth, registering a slight dip in starlight brightness. The 1,235 candidates will be confirmed (or denied) as Kepler awaits future transits.

Detecting the slight dimming of starlight isn’t the only tool exoplanet hunters have to spot these alien worlds. The “radial velocity” method — as employed by systems such as the ESO’s HARPS — can detect the slight “wobble” of stars as orbiting worlds gravitationally “tug” on their parent stars. Both methods have their advantages and both are notching up an impressive exoplanet count. “Microlensing” has also been employed to spot a handful of exoplanets, as has direct imaging.

Exoplanetary studies are amongst the most exciting astronomical projects out there. Not only are we realizing there is a veritable zoo of worlds — some Earth-sized, others many times the mass of Jupiter — we are also pondering the most profound question: could extraterrestrial life inhabit these worlds?

For now, we have no clue, but life as we know it has a habit of springing up where we least expect it, it’s only a matter of time before we start to have some clue as to the existence of life as we don’t know it.

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Some Galaxies Die Young… Others Recycle

Some galaxies undergo a rapid star formation phase, losing stellar gases to intergalactic space, others choose to recycle, thereby extending their star forming lifespans.

Some galaxies undergo a rapid star formation phase, losing stellar gases to intergalactic space, others choose to recycle, thereby extending their star forming lifespans (NASA, ESA, and A. Feild (STScI))

It sounds like an over-hyped public service announcement: If you don’t recycle, you’ll die a premature death.

But in the case of galaxies, according to three new Science papers based on Hubble Space Telescope data, this is a reality. Should a galaxy “go green,” reusing waste stellar gas contained within huge halos situated outside their visible disks, they will fuel future star-birth cycles, prolonging their lifespans.

Sadly for “starburst” galaxies — galaxies that undergo rapid star generation over very short time periods — they care little for recycling, resulting in an untimely death.

Using data from Hubble’s Cosmic Origins Spectrograph (COS), three teams studied 40 galaxies (including the Milky Way) and discovered vast halos of waste stellar gases. Contained within these spherical reservoirs — extending up to 450,000 light-years from their bright disks of stars — light elements such as hydrogen and helium were found to be laced with heavier elements like carbon, oxygen, nitrogen and neon. There’s only one place these heavy elements could have come from: fusion processes in the cores of stars and supernovae.

Interestingly, the quantity of heavy elements contained within the newly-discovered halos is similar to what is contained in the interstellar gases within the galaxies themselves.

“There’s as much heavy elements out in the halos of the galaxies as there is in their interstellar medium, that is what shocked us.” said Jason Tumlinson, an astronomer for the Space Telescope Science Institute in Baltimore, Md., in an interview for my Discovery News article “Galaxies That Don’t Recycle Live Hard, Die Young.”

But these heavy elements are stored in halos outside the galaxies; how the heck did it get there?

According to the researchers, powerful stellar winds jetting into intergalactic space have been observed, transporting the heavy elements with them. But there’s a catch. If the outflow is too strong, waste stellar gases are ejected from the galaxies completely. Unfortunately for one sub-set of galaxies, powerful stellar outflows come naturally.

Starburst galaxies rapidly generate stars, ejecting speedy streams of stellar waste gas. Some of these streams have been clocked traveling at 2 million miles per hour, escaping from the galaxy forever. In the case of a starbust galaxy, a “recycling halo” cannot be re-supplied — future star birth is therefore killed off.

“We found the James Dean or Amy Winehouse of that population, you know, the galaxies that lived fast and died young,” Tumlinson pointed out. “(Todd) Tripp’s team studied that in their paper.”

“That paper used a galaxy that is known as a ‘post-star burst galaxy’ and its spectrum showed that it had a very robust star burst (phase),” he continued. “It was one of those live fast, die young galaxies.”

Although fascinating, one idea struck me the hardest. On asking Tumlinson to speculate on how galactic recycling of stellar material may impact us, he said:

“Your body is 70 percent water and every water molecule has an oxygen atom in it. The theorists say the recycling time (in the Milky Way’s halo) is approximately a billion years, so that means — potentially — that some of the material (oxygen) inside your body has cycled in and out of the galaxy ten times in the history of the galaxy. At least once, maybe up to ten times.”

As Carl Sagan famously said: “We’re made of star stuff;” perhaps this should be rephrased to: “We’re made of recycled star stuff.”


When an Astrophysicist Needs a Star Map

Stars of the Northern Hemisphere, Ashland Astronomy Studio

Stars of the Northern Hemisphere, Ashland Astronomy Studio

Imagine the scene: I’m having a romantic walk on a clear night with my wife along the beach. We see a brief flash of light and Deb says, “Hey, a meteor!” I then proceed to tell her that most meteors are actually no bigger than a grain of sand and they originate from comets, even though she already knew that. Feeling quite chuffed with myself that I was able to describe a nugget of atmospheric dynamics in 2 minutes, Deb then points up again and says, “There’s Orion. What constellation is that one?”

“Um. I have no idea,” I reply, feeling less smug. “I know how those things work, but I don’t know what they look like.”

I don’t own a telescope (yet) and I only took one course in university on practical astronomy, everything else was astrophysics. So the sad thing is that I know how stars work — from the nuclear fusion in their core to coronal dynamics (the latter of which I did my PhD in) — but if anyone asked me to point out a constellation or the location of a star… I wouldn’t have a clue.

Sure, there are the old favorites, like Orion, the Big Dipper (or Plough) and bright Polaris, but my expertise in night sky viewing is pretty limited. Although I’d usually refer any astronomy-related questions to BBC astronomy presenter (and Discovery News writer) Mark Thompson, I’d love to learn more. So, firstly, I needed a star chart.

Luckily, a few weeks ago, I received a random email from Erik Anderson from Ashland Astronomy Studio asking whether I’d like a copy of his company’s new star map poster. Being eager to boost my pitiful knowledge of the constellations, I jumped at the chance. Soon after, my poster arrived through the post.

Now this is where things got really cool. Although Erik had titled his email to me “Star Map with Exoplanet Hosts,” I’d forgotten about the “exoplanet” part. On the clear, yet detailed Ashland star map, all the major constellations and stars are plotted, along with the time of the year (in the Northern Hemisphere) they can be seen. But also, there’s a symbol representing the hundreds of stars that are known to have exoplanetary systems orbiting.

Over the last couple of weeks, I’ve been referring to my newly-framed star map, and can now confidently point into the sky, not only identifying the constellations but also some stars that possess exoplanets. Only last night, I pointed up in the general vicinity of the star 61 Virginis (near the blue giant Spica) and said, “That star has 3 worlds orbiting it.”

I’m not sure if Deb was overly impressed with my exoplanet knowledge, but I was happy to be smug again.

Although it’s only a very small part of an astronomer’s tool kit, a star map is essential. Although you can get apps for your iPhone, you can’t beat a poster that isn’t only functional, but also looks very attractive on your office wall.

The very cool Ashland Astronomy Studio Star Map can be purchased from Amazon.

Could Kepler Detect Borg Cubes? Why Not.

That's no sunspot.

"That's no sunspot."

Assuming Star Trek‘s Borg Collective went into overdrive and decided to build a huge cube a few thousand miles wide, then yes, the exoplanet-hunting Kepler space telescope should be able to spot it. But how could Kepler distinguish a cube from a nice spherical exoplanet?

With the help of Ray Villard over at Discovery News, he did some digging and found a paper dating back to 2005 — long before Kepler was launched. However, researcher Luc Arnold, of the Observatoire de Haute-Provence in Paris, did have the space telescope in mind when he studied what it would take to distinguish different hypothetical shapes as they passed in front of his theoretical stars.

The big assumption when looking for exoplanets that drift between distant stars and the Earth — events known as “transits” — is that the only shape these detectable exoplanets come in are spheres. Obvious really.

As a world passes in front of its parent star, a circular shadow will form. However, from Earth, we’d detect a slight dimming of the star’s “light curve” during the transit, allowing astronomers to deduce the exoplanet’s orbital period and size.

The transit method has been used to confirm the presence of hundreds of exoplanets so far, and Kepler has found over 1,200 additional exoplanet candidates. But say if astronomers paid closer attention to the shape of the received light curve; spherical objects have a distinct signature, but say if something looked different in the transiting “planet’s” light curve? Well, it could mean that something non-spherical has passed in front of a star. And what does that mean? Well, that would be a pretty convincing argument for the presence of a huge planet-sized artificial structure orbiting another star. Artifical structure = super-advanced alien civilization.

Arnold tested his theory that all manner of shapes could be detected by Kepler, assuming the transiting structure was on the scale of a few thousand miles wide. In this case, Arnold was testing his hypothesis to see whether we could detect an advanced civilization’s “shadow play.” Perhaps, rather than beaming messages by radio waves, an advanced civilization might want to signal their presence — SETI style — by blocking their sun’s light with vast sheets of lightweight material. As the shape passes in front of the star, the slight dimming of starlight would reveal an artificial presence in orbit.

By putting a series of these shapes into orbit, the aliens could create a kind of interstellar Morse code.

Of course, this is a rather “out there” idea, but I find it fascinating that Kepler could detect an alien artifact orbiting a star tens or hundreds of light-years away. Although this research is only considering orbital “billboards,” I quite like the idea that Kepler might also be able to detect a large structure like… I don’t know… a big Borg mothership. Having advanced warning of the presence of an aggressive alien race sitting on our cosmic doorstep — especially ones of the variety that like to assimilate — would be pretty handy.

Publication: Transit Lightcurve Signatures of Artificial Objects, L. Arnold, 2005. arXiv:astro-ph/0503580v1

Jupiter Got Smacked, Again

Quite frankly, I’m stunned.

An Australian amateur astronomer has just observed his second ‘once-in-a-lifetime’ event: an impact in the atmosphere of Jupiter. Phil Plait was very quick to get the news out, describing it as a “major coincidence,” and he ain’t wrong!

Anthony Wesley’s first event was the famous July 2009 observation of what was thought to have been the immediate aftermath of a comet impact in the Jovian atmosphere. His second happened on Thursday at 20:31 UTC when he was observing Jupiter when something hit the atmosphere, generating a huge fireball.

It is not known whether this event was caused by a comet or asteroid, but in a bizarre case of serendipity, earlier on Thursday Hubble released more information on his original impact event. The July 2009 “bruise” in the gas giant’s atmosphere is now thought to have been caused by an asteroid, and not a comet.

The Hubble press release included details on how researchers deduced that it was actually more likely that a 500 meter-wide asteroid hit Jupiter in 2009. One clue was that newly installed cameras on the space telescope detected little dust in the halo surrounding the impact site — a characteristic that was detected after the impact of the shards of comet Shoemaker-Levy 9 in July 1994. Also, the calculated trajectory of the 2009 event indicated the object didn’t have an orbit commonly associated with comets. If the 2009 event was an asteroid, that means Wesley saw something never seen before: the site of a recent asteroid impact on a celestial body.

And now, less than a year after being the first to see that impact aftermath, Wesley has done it again. Another amateur astronomer, Christopher Go, was quick to confirm Thursday’s fireball with a video of the 2 second flash in Jupiter’s upper atmosphere.

These impact events serve as a reminder about Jupiter’s fortuitous role in our Solar System. As the gas giant is so massive, its gravitational pull has a huge influence over the outer planets, dwarf planets, comets and asteroids. Acting like an interplanetary ‘vacuum cleaner’ Jupiter can block potentially disastrous chunks of stuff from taking a dive into the inner Solar System. It is thought that this distant planet has helped Earth become the thriving world it is today, preventing many asteroids and comets from ruining our evolution.

Thank you Jupiter!

Hubble Conquers Mystic Mountain

Where is that mystical land? (NASA/ESA/HST).

Where is this mystical land? (NASA/ESA/HST).

Sometimes, words are not enough to describe views of the universe when captured through the lens of the Hubble Space Telescope. This is one of those moments.

Kicking off its 20th anniversary (yes, that super-sized telescope has been in space that long — I would say that I remember it being launched, but I don’t, because I was nine, playing with my Star Wars toys), Hubble has published some astonishing images of deep inside the Carina Nebula, some 7,500 light-years from Earth. And, quite frankly, I’m floored.

BIG PIC: Have a look deep inside the Carina Nebula with some of my Discovery News coverage of the event.

The pillar of gas and dust looks like a gnarled tree branch, dotted with sparkling lights. The Hubble press release even describes the structure as a “Mystic Mountain,” and it’s not hard to see why. In this age of computer generated everything, this release of images show that the cosmos contains things that defy our tiny imaginations.

We are looking at a star-forming region, deep inside the nebula, where stars are being born inside the bulbous towers of gas and dust, but on the outside, young stars are battering the tower with intense stellar winds and powerful radiation. The pillar is being eroded away. However, this exterior pressure is seeding the birth of new stars inside the nebulous material.

The mindblowing clarity of this Hubble observation even brings out the fine detail in the jets of ionized gas as it is blasted from the point of the tallest finger of material. This is being generated by a young star, gorging itself on gas, forming a superheated accretion disk, blasting the energized gas out from the stellar nursery.

As Hubble’s 20th anniversary celebrations continue, I think we can expect a lot more where this came from. So brace yourself, this gem of a space telescope may be getting old, but it still has a shedload of cosmos to show us.

Now, lets stand back and get a better view of the incredible floating ‘Mystic Mountain’…

The Carina stellar nursary from afar (NASA/ESA/HST)

The Carina stellar nursary from afar (NASA/ESA/HST)

Then Spitzer Imaged Baby Stars in the Orion Nebula…

The Orion Nebula's star-forming region (NASA)

The Orion Nebula's star-forming region (NASA).

Firstly, apologies that it’s been over a month since last posting to Astroengine.com. Call it slacking off, call it a sabbatical, either way, it’s not good. I’ve actually prepared several half-finished articles, but I just never got around to completing them. However, I have been on writing overdrive over at Discovery News, so if I go quiet over here, you know where to find me.

Speaking of Discovery News, I’ve just posted an incredible image of the heart of the Orion Nebula as seen by the Spitzer Space Telescope, so I can’t think of a better way to kick-start Astroengine with an image filled with awesomeness.

Although Spitzer has entered a new phase of operations since it depleted the liquid helium coolant used to maintain its instrumentation, that doesn’t mean its stopped producing some awe-inspiring imagery. In a new vista released on Thursday, a bustling star formation region in Orion is detailed, showing some 1,500 young stars the observatory watched for 40 days. This is an unprecedented study, allowing rapid variations in these baby stars to be tracked by Spitzer.

Young stars are generally highly variable in their brightness, a characteristic that is of huge interest to astrophysicists. If we can understand the mechanisms causing this variation, we can gain an insight to stellar evolution, possibly even understanding the history of our own Solar System.

As Spitzer observes in infrared wavelengths, it’s very sensitive to clouds of dust being heated by these young stars. Therefore, the proto-planetary disks surrounding these million year old stars glow brightly. Not only does this give an indication to the conditions surrounding the star, it also provides astronomers with an idea to how these disks of dust clump together, slowly evolving into exoplanets. And now Spitzer has data sets spanning weeks, dynamic changes in the emissions from the stars and their evolving planetary systems can be studied.

But science aside, the Spitzer imagery is a thing of beauty, reminding us how complex our cosmos really is. Don’t believe me? Take a look for yourself (click the pic to dive right in):

The star forming region in Orion as studied by Spitzer, rotated 90 degrees (NASA/JPL/Caltech)

The star forming region in Orion as studied by Spitzer, rotated 90 degrees (NASA/JPL/Caltech)