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.