Exoplanet Explorer: WASP 12b

September 28, 2017

Imagine you’re a poor, helpless planet orbiting a normal yellow dwarf star, a star not so dissimilar to our own Sun. But that star keeps drawing you closer and closer… and closer. You know this could end badly for you, but you cannot resist. Soon, it’s too late. Like the monster from Stephen King’s It, the star is going to eat you alive.

Such is the fate of WASP 12b, an exoplanet discovered in 2008 by the SuperWASP planetary transit survey. Wasp 12b is a carbon rich planet, with an atmosphere of mostly methane and carbon monoxide, and astronomers suspect the planet’s core might be made of graphite and diamond.

You could describe WASP 12b as a hot Jupiter, a gas giant that’s strayed perilously close to its parent star. WASP 12b is also sometimes referred to as a chthonian planet, though in my opinion that seems a bit premature. The planet appears to be in its final death throes, so to speak, but it’s not quite dead yet.

In 2010, observations by the Hubble Space Telescope revealed that the planet’s atmosphere is being stripped away, with streams of matter falling toward the star to be “consumed.” Eventually all that will remain of WASP 12b is its core. At that point, I think the term chthonian planet will be appropriate.

That is assuming, of course, that anything will remain at all. Given how violently WASP 12b is being destroyed, it’s possible even that diamond core will be ripped apart and devoured. According to current estimates, we’ll have to wait about 10 million years to find out—a surprisingly short period of time in the cosmic scheme of things.

P.S.: To my surprise, WASP 12b has started making headlines just in the last few days. Astronomers recently determined the planet is incredibly dark in color, almost pitch black. That seemed strange to me at first, but I guess if you’re going to have a planet with that much carbon, the dark coloration kind of makes sense.


Exoplanet Explorer: COROT 7b

September 26, 2017

In 2009, the French-built COROT space telescope made an astonishing discovery: a planet. A planet that was, at least at the time, the most Earth-like exoplanet ever discovered. Except as we’ve discussed previously, “Earth-like” exoplanets are not necessarily much like Earth. In this case, the term chthonian planet may be a better fit.

Exoplanets are often named after the telescope used to discover them; therefore, this planet has been officially designated COROT 7b (the T, by the way, is silent… it’s a French thing). A press release announcing COROT 7b’s discovery said it has a surface you can walk on. That’s true enough, but I don’t recommend going for a stroll there. The weather forecast sounds terrible.

It’s believed that COROT 7b started out as a gas giant, like Jupiter or Saturn, but it was drawn into an orbit way too close to its parent star. Due to the star’s intense heat and radiation, COROT 7b’s entire atmosphere would have boiled away, leaving only the shrunken, shriveled core of the planet behind.

That shrunken core, which is still orbiting way too close to its parent star, is predicted to be tidally locked, meaning one side of the planet is always facing the sun and the other side is always turned away. That creates an enormous temperature discrepancy similar to, but more extreme than, the temperature discrepancy on Mercury.

And according to this paper from the Royal Astronomy Society, the temperature on the daylight side is high enough to vaporize rock. Allow me to emphasize that point. It’s not just hot enough to melt rock; oh no, that would be too normal. It’s hot enough to vaporize rock. So while COROT 7b seems to have lost its original atmosphere, it may have developed a new atmosphere composed of gaseous sodium and silicon and iron, along with other things we’re not accustomed to thinking of as atmospheric gases.

Then on the night side, where the temperature is much colder, all that vaporized rock would condense to form “mineral clouds,” and pebbles would fall like rain. Or perhaps hail is a more apt analogy. Anyway, if you’re going to go for a walk on COROT 7b, you’ll need more than an umbrella to deal with the weather.


Exoplanet Explorer: Gliese 504b “Pinkie Pie”

August 16, 2017

Continuing our exploration of the exoplanets, today we’re visiting a planet called Gliese 504b.

Gliese 504b isn’t the kind of alphanumeric gobbledygook we usually get for exoplanet designations, but still… I prefer actual names, or at least nicknames. I think it’s easier to write about a planet when it has a name, and names help give us a sense of a planet’s personality.

So as of today, I’m officially renaming Gliese 504b Pinkie Pie.

Wait, I shouldn’t have used the word “officially.” I’m just some guy with a blog. Only the International Astronomy Union has the authority to…

“Pinkie Pie” was discovered in 2013 orbiting a Sun-like star about 57 lightyears away in the constellation Virgo. This was one of those rare cases where astronomers were able to directly image a planet orbiting another star, and they could even identify the planets color. This made headlines, because the planet turned out to be pink. Glorious, fabulous bright hot pink!

The pink color is apparently due to the planet’s age. It’s only a few hundred million years old, which is young for a planet, and it’s still glowing from the heat of its formation. It appears to be a gas giant, several times more massive than Jupiter.

Also, it seems the topmost layers of clouds aren’t there. Perhaps the kinds of swirling, opaque clouds we’re accustomed to seeing on giant planets like Jupiter or Saturn will form later on as Pinkie Pie grows older and cools off. In the meantime, as telescope technology improves, Pinkie Pie may offer us an unprecedented opportunity to see how gas giants are structured on the inside.

Before I end this post, there is one more thing that you should know about Pinkie Pie. It’s rather important. There’s an ongoing mystery as to how a planet so young could be orbiting so far away from its parent star. According to our current understanding of planetary formation, gas giants like Pinkie Pie should be much closer in. Unless maybe Pinkie Pie isn’t a planet after all!

Yes, Pluto isn’t the only one to have its planet status called into question. Except while Pluto is essentially too small for planethood, Pinkie Pie might be too big. Some astronomers suggest that Pinkie Pie should be classified as a brown dwarf.

Of course that depends on how the term brown dwarf is defined. More about that in Friday’s edition of Sciency Words.


Exoplanet Explorer: Poltergeist

May 10, 2017

Today’s post is part of a semi-regular series here on Planet Pailly exploring exoplanets: planets orbiting stars other than our Sun. Today, we’re exploring the exoplanet:

POLTERGEIST

In 2015, our friends at the International Astronomy Union gave in to public pressure and finally started assigning actual names to exoplanets. Thus, the exoplanet designated PSR B1257+12 c is now known as Poltergeist.

Poltergeist is actually the very first exoplanet we humans ever discovered. It’s approximately four times as massive as Earth, has an orbital period of 66 days, and is located in a star system roughly 2,300 light-years away in the constellation Virgo.

It’s hard to say much else about a planet so far away from us, but based on what we do know at this point, I’m willing to bet Poltergeist is a barren rock stripped of any appreciable atmosphere and depleted of all or almost all of its volatiles.

That’s because Poltergeist’s sun is no ordinary star. It’s a pulsar: the tiny, rapidly-spinning, gamma radiation flashing remnants of a star that went supernova. As of 2015, the I.A.U. has named this pulsar Lich, and there are two other planets in the Lich System: Draugr and Phobetar. The official naming scheme for this system is apparently the undead.

  • Lich: an undead thing with magic powers to control other undead things.
  • Draugr: a reanimated corpse from Norse mythology.
  • Poltergeist: a ghost, especially a noisy and troublesome ghost.
  • Phobetor: the ancient Greek god of nightmares.

According to this paper (published in 1993, right after the discovery of Poltergeist and Phobetor but before the discovery of Draugr), there are quite a few scenarios that could explain how a pulsar like Lich ended up with its own planets. We can’t say for sure which scenario is correct, but all the most likely scenarios have one thing in common: the planets formed after the supernova.

Perhaps the planets that existed before the supernova were destroyed, and Poltergeist and company re-coalesced from the rubble (this paper from 2015 seems to rule that possibility out). Or perhaps Lich was once part of a binary system, and the planets formed after Lich ripped its companion star apart. Or maybe Lich is the product of a violent merger of two white dwarf stars, or a white dwarf and a neutron star, with the planets forming from matter the got spewed into space during the merger (this is reportedly the most plausible scenario).

So it would seem Poltergeist and the other planets of the Lich System really are the ghosts left over by some cataclysmic event (even if we’re not certain which specific cataclysm occurred) which is why their creepy, Halloween-style names are so appropriate.


Exoplanet Explorer: Orbitar

December 12, 2016

Today’s post is the first in what I hope will become a semi-regular series about exoplanets: planets that orbit stars other than our Sun. I’ve decided to start with an exoplanet named Orbitar.

dc12-orbitar

In December of 2015, the exoplanet designated 42 Draconis b was officially renamed Orbitar following a public naming contest held by the International Astronomy Union. Orbitar is a gas giant planet orbiting a red giant star approximately 315 light-years away in the constellation Draco.

Discovering Orbitar

The gravitational pull between planets and the stars they orbit causes stars to wobble in place. When the star 42 Draconis was found to wobble at a regular interval of 479 days, it was determined that a large planet with a 479 day orbital period was likely responsible.

Further calculations determined that this planet had an average orbital distance of 1.19 AU and an orbital eccentricity of 38%. The planet’s total mass was estimated to be equivalent to at least 3.88 Jupiters, give or take 0.85 Juptiers.

Life on Orbitar’s Moons?

According to the Brevard Astronomical Society, the group that won the IAU naming contest for Orbitar, “this closely orbiting gas planet could possibly host moons with Earth-like characteristics in the so-called habitable zone.”

Personally, I feel that’s a bit over-optimistic. At an orbital distance of 1.19 AU, Orbitar and its hypothetical moons would certainly would be within our Sun’s habitable zone, but 42 Draconis (which was renamed Fafnir in the IAU contest) is over twice our Sun’s age and has entered the red giant phase of its life cycle.

I may be wrong about this, but I’d expect that Fafnir’s habitable zone would lie well beyond the 1.19 AU distance. Orbitar’s moons (if they exist) should have been charred to cinders by now.

However, that still leaves us with the possibility that Orbitarian life could have existed at some point in the distant past, when Fafnir was still young and still a main sequence star like our Sun.

P.S.: As far as I can tell, the name Planety McPlanetface was not submitted to the IAU’s planet naming contest.

Links

Orbitar, Really? Some New Exoplanet Names Are Downright Weird from Ars Technica.

Planetary Companion Candidates Around K Giant Stars 42 Draconis and HD 139 357 from Astronomy & Astrophysics.

Name Exoworlds: An IAU Worldwide Contest to Name Exoplanets from the International Astronomy Union.