The Highly Conspicuous Rings of Proxima c

Hello, friends!  As you know, Saturn is a really pretty planet.  That’s not an opinion.  It’s a scientific fact.  But in the solar system right next door to our own, there is a planet even prettier than Saturn.  As you can see in the highly technical diagram below, the planet Proxima Centauri c may be the brightest, shiniest, prettiest planet known to human science!

The last time I wrote about Proxima Centauri c, the planet was only suspected to exist, based on circumstantial evidence.  But according to this press release, Proxima c’s existence is now confirmed.  Additional data about the planet was found in archived Hubble Space Telescope images dating back to the 1990’s.

However, certain details about Proxima c remain difficult to explain.  Most notably, the planet (as observed in infrared light) appears to be way, waaaay brighter than we would expect, based upon its estimated mass (approximately seven times the mass of Earth).  In my highly technical diagram, I tried to make Proxima c look as bright and shiny as possible, but I’m starting to think I didn’t make the planet bright and shiny enough!

According to this paper on Proxima c’s infrared signature, one possible explanation is a “conspicuous ring system” that’s reflecting a whole lot of extra sunlight.  If that’s the case, Proxima c really would be a stunningly beautiful sight, with wide, glorious rings that would put the rings of Saturn to shame.  However, that same paper offers other possible explanations that sound far more grim.  Something horrible may have happened to Proxima c and/or its moons.  But I’ll save that for Friday’s episode of Sciency Words.

P.S.: If you own a backyard telescope or a pair of binoculars and want to see Proxima c for yourself, well… you can’t.  But if you have access to a high powered astronomical observatory, there’s a really interesting technique that can help you find Proxima c and planets like it.  Science communicator Elizabeth Tasker has written an excellent article about that.  Click here!

If Proxima c Exists, It Must Be Beautiful!

Hello, friends!

For over a week now, I’ve been teasing you with promises of a very pretty picture of a very pretty planet.  Proxima Centauri is already known to have at least one planet, named Proxima b.  Now a second planet, Proxima c, may have also been discovered.

So how do we know Proxima c is there?  Well, we don’t.  I would be an irresponsible science blogger if I didn’t make this 100% clear: astronomers do not know for certain if Proxima c exists.  The evidence, as it currently stands, is highly circumstantial.

  • First off, we have the possible detection of asteroid belts encircling Proxima Centauri.  The presence of asteroid belts would imply the presence of planets, since it would take a planet’s gravity to keep the gaps between those asteroid belts clear.
  • Second, as reported in this paper, we have the possible detection of a “compact source” of thermal emissions.  There could be multiple explanations for this, but one possibility is a planet with a large, Saturn-like ring system.
  • Lastly, according to this paper, Proxima Centauri is wobbling in place.  That sort of wobbling in a star usually means a planet’s gravity is tugging on that star.  Usually.

As I said, all this evidence is highly circumstantial.  Proxima Centauri is known to have extremely violent solar flares, which may also explain why the star is so wobbly.  And that compact source of thermal emissions could be lots of things other than a planetary ring system (it might even be an error in our data).  And as for Proxima’s asteroid belts, we haven’t confirmed those exist yet.  It would be premature to say anything about possible planets based on possible asteroids.

But as this article from Scientific American explains it, all this circumstantial evidence seems to be lining up in such a way that you have to go hmmm.  If Proxima Centauri’s wobbles are caused by a planet, astronomers can make an educated guess about where that planet must be located.  And that location lines up with that compact source of thermal emissions.  And that compact source of thermal emissions is right where a planet would need to be to keep the gap between the asteroid belts clear. Coincidence? Well, maybe.

Again, this is highly circumstantial evidence.  It will take a lot more observation and data analysis to determine whether or not Proxima c is really there.

But for a planet that may not exist, we know an awful lot about what Proxima c should be like.  Based on Proxima Centauri’s wobbliness, we know Proxima c must be more massive than Earth, but less massive than Neptune.  We also know it must be very cold.  It’s a long way away from the habitable zone.  Due to Proxima Centauri’s intense solar flare activity, we’d expect Proxima c to have some crazy bright aurorae.  Oh, and as we already established, Proxima c would have a large, Saturn-like ring system.

In short, Proxima c sounds like it must be a very pretty planet.

If it exists.  Which is still a pretty big if.

Quick programming note: I’m going to take a few days off from blogging.  I’ll be away on a trip to visit family.  My grandmother is turning 100 years old this weekend, so it’s going to be a party!

I’ll be back some time next week with updates about my book and an announcement about this year’s A to Z Challenge.  See you soon!

Sciency Words: Null Hypothesis

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we look at the meaning and origins of scientific terms.  Today on Sciency Words, we’re talking about:

THE NULL HYPOTHESIS

Whenever there’s a big scientific discovery in the news, my first question is always: should I take this seriously?  The answer is usually no.  The popular press may say one thing, but when you dig into the actual science, you often find the facts do not support the hype.

So when I started reading about a second possible planet in the Proxima Centauri system, I wanted to know: should I take this seriously?  In this article from Scientific American, the astronomers who discovered this possible planet are quoted as saying:

Since the very first time we saw this [potential planetary] signal, we tried to be its worst enemy.

The astronomers are then quoted saying:

We tried different tools to prove ourselves wrong, but failed.  However, we have to keep the doors open to all possible doubt and skepticism.

For me, this is the most reassuring thing any scientist could say.  Too often in popular culture, scientists are portrayed a certain way.

For a multitude of reasons, this is not a real scientist.

But no, good scientists are not out to prove to the world that they’re right.  They’re trying as hard as possible to prove to themselves that they’re wrong.  Which brings me to the null hypothesis.

According to the Oxford English Dictionary and other sources (like this one), the term “null hypothesis” can be traced back to British statistician Ronald Fisher.  Fisher first wrote about the null hypothesis in 1935, in a book titled The Design of Experiments.

As a way of introducing the concept, Fisher tells us the story of a woman who claimed to have an oddly specific talent.

A lady declares that by tasting a cup of tea made with milk she can discriminate whether the milk or the tea infusion was first added to the cup.

The Design of Experiments, by Ronald Fisher

Fisher then describes an experiment to test this woman’s claim.  She’s given eight cups of tea, four with the milk added first, and four with the milk added afterward.

In the context of this experiment, the null hypothesis predicts that the woman will not be able to tell which tea is which—she’s only guessing.  Or to put that in sciencier language, the null hypothesis asserts that there will be no statistically significant relationship between the way this woman’s tea was prepared and the way she believes her tea was prepared. As Fisher explains:

[…] it should be noted that the null hypothesis is never proved or established, but is possibly disproved, in the course of experimentation.  Every experiment may be said to exist only in order to give the facts a chance of disproving the null hypothesis.

The Design of Experiments, by Ronald Fisher

A null hypothesis is usually paired with an “alternative hypothesis,” which asserts that a statistically significant relationship does exist.  In Fisher’s tea tasting example, the alternative hypothesis would be that the woman really can tell which tea is which.  You can never really prove that either the null hypothesis or the alternative hypothesis is true, but a well designed experiment should be able to prove that one hypothesis or the other is false.

Going back to that possible planet in the Proxima Centauri system, the article from Scientific American does not explicitly mention the null hypothesis; however, the spirit of the null hypothesis is clearly in play.  Astronomers are trying their best to prove that that planet does not exist, and so far they can’t do it.  And that’s enough to convince me that I should take this new planet seriously (at least for now).

Next time on Planet Pailly, we’ll find out what this not-yet-disproven planet might look like.

Touring Proxima Centauri’s Asteroid Belts

Hello, friends!

As you know, sometimes things don’t go according to plan.  For today’s post, I was planning to draw a really pretty picture of a really planet—a planet that astronomers may (or may not) have found in the Proxima Centauri system.  But as I did my research about this possible planet, I realized I needed to draw something else for you first.

As reported in this 2017 paper, temperature readings indicate that Proxima Centauri may have at least one and as many as three asteroid belts.  Based on what I’ve read, it sounds like the presence of these belts has not been definitively proven yet.  But no one seems to be able to definitively disprove them either.

So here is a map of everything we currently know or suspect exists in the Proxima Centauri system.

As you can see, the planet Proxima b is in an extremely tight orbit around its star.  But since Proxima Centauri is much smaller and cooler than our Sun, Proxima b is technically in the star’s habitable zone.  Click here for my post on whether or not Proxima b could actually support life.

Beyond the orbit of Proxima b, we find our first possible asteroid belt.  In that 2017 paper I cited above, this innermost belt is described as the warm dust belt.  It appears to be located approximately 0.4 AU away from its star (roughly equivalent to the orbit of Mercury in our Solar System).

A little farther out, we find a second possible asteroid belt, which the authors of that 2017 paper describe as the cold dust belt.  Remember: we suspect these dust belts exist because of temperature measurements, hence the names.  The cold dust belt appears to be spread out between 1 AU and 4 AU (roughly equivalent to the space between the orbits of Earth and Jupiter in our Solar System).

And then farther out still, there appears to be a third belt, referred to as the outer dust belt (in my opinion, it should have been named the colder dust belt).  The outer dust belt appears to be located approximately 30 AU away from its star (roughly equivalent to the orbit of Neptune).

I want to emphasize again: as far as I can tell from my own research, no one has definitively proven or disproven these dust belts exist.  All we have are some temperature measurements that suggest something might possibly be there.

But if all those dust belts do exist, that tells us there should be planets orbiting in the gaps between the belts.  It would take a planet’s gravity to keep those gaps empty.  And now that you know that, I think we’re ready to take a closer look at Proxima c.

Except tomorrow is Insecure Writer’s Support Group day, so our trip to Proxima c will have to wait.  But I promise the wait will be worth it.  Science predicts that if Proxima c really exists, it must be the most gorgeous planet you’ve ever seen!

Next time on Planet Pailly, the unexpected benefits of having your manuscript edited.

How Proxima b Lost Its Ozone Layer

Hello, friends!

Today we’re visiting Proxima Centauri, one of three stars in the Alpha Centauri system, the star system right next door to our own.  And it turns out Proxima has at least one planet.  Not only that: Proxima’s planet is orbiting within the habitable zone.  That planet may have liquid water on its surface, and perhaps even life!

Proxima’s planet, known officially as Proxima b, orbits about 0.05 AU away from its star.  That puts Proxima b closer to its star than Mercury is to our Sun.  But that’s okay.  Proxima Centauri is much smaller, dimmer, and colder than our own Sun, so everything balances out.

But I have bad news.  The temperature might be right for life, but the radiation environment is all wrong.  Proxima Centauri is a very angry little star.  It’s much angrier than our Sun.  Solar flares, solar wind, and solar radiation are a whole lot worse than anything Earth would normally have to worry about.

In March of 2016, Earth-based astronomers observed a “superflare” on Proxima Centauri.  As you can see in the highly technical diagram below, that superflare would have done serious damage to Proxima b’s ozone layer (assuming Proxima b had an ozone layer in the first place).

According to this 2018 paper on ozone loss, if superflares like that are normal for Proxima Centauri, we should expect Proxima b to lose 90% of its ozone layer in just five years (again, assuming Proxima b had an ozone layer in the first place).  Without an ozone layer, incoming ultraviolet radiation would thoroughly sterilize Proxima b’s surface (much like it does on Mars).

And it gets worse.  Earth’s magnetic field deflects a lot of harmful solar and cosmic radiation away.  But according to this 2016 paper on space weather, Proxima b’s magnetic field (assuming Proxima b has a magnetic field) is taking a real beating.  The magnetic field would be badly weakened and compressed.  As a result, Proxima b’s atmosphere would start eroding away, due to the solar wind, and if those UV rays haven’t already killed everything on the surface, all that solar and cosmic radiation would have a chance to finish the job.

Even the most extreme of extremophiles here on Earth would have a tough time surviving on Proxima b.  But the situation is not hopeless.  That 2016 paper on space weather and that 2018 paper on ozone loss both acknowledge that there are still plausible scenarios where life could evolve and thrive on Proxima b.  But in order to do it, the Proxima b-ians must have done one of two things:

  • Life on Proxima b must be very specifically adapted to that radiation environment, or…
  • Life on Proxima b must have found a good hiding place, perhaps deep underwater or underground, where the radiation can’t reach it.

Next time on Planet Pailly, it’s a bird!  It’s a plane!  It’s… oh no, it’s a killer asteroid!!!

Sciency Words: Flare Star

Sciency Words BIO copy

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us all expand our scientific vocabularies together. Today’s term is:

FLARE STAR

Good Star Trek fans will remember the Battle of Wolf 359, when the Borg came to assimilate us all. Thirty-nine Federation starships were lost. Nearly 11,000 people were killed. #NeverForget

Good Trekkies may also be aware of the fact that Wolf 359 is a real place. It’s a red dwarf star in the constellation Leo, located within a mere eight light-years from Earth.

Also, Wolf 359 is a UV Ceti variable star, or what is more commonly called a flare star. Flare stars experience dramatic, unpredictable increases in brightness across the EM spectrum, including increases in highly destructive X-ray and gamma ray emissions.

And when a flare star starts to flare up, it can happen quickly. In 1952, the star UV Ceti (for which the UV Ceti variable star category is named) became about 75 times brighter in a period of only twenty seconds.

It’s believed that the flare activity of flare stars is similar to the kind of solar flares we’ve observed on our own Sun. Except the Sun’s solar flares are usually not so intense. And when it comes those X-rays and gamma rays, our Sun doesn’t even come close to what spews out of flare stars.

So perhaps parking thirty-nine starships next to a flare star wasn’t the smartest thing Starfleet could have done. Maybe… just maybe… what happened at Wolf 359 wasn’t the Borg Collective’s fault.

Ag26 Battle of Wolf 359

P.S.: Another flare star has been in the news a lot lately: Proxima Centauri. We now know, thanks to the European Southern Observatory, that Proxima does have an Earth-like planet in orbit. So the next question is just how thoroughly that planet has been cooked by Proxima’s violent flare-ups.

Proxima Centauri Has a Planet!

Ohmigod, ohmigod, ohmigod!

Okay, calm down, James. Breathe. Breathe.

Okay. Let’s take a look at Alpha Centuari, a binary star system located within a mere 5 light-years from Earth. In the bottom corner of the image, you can see a red dwarf star called Proxima Centauri, which is believed to be a companion to the Alpha Centauri pair. And in orbit of Promixa, you can see… you can see… ohmigod!

Ag16 Alpha Centauri

Apparently the European Southern Observatory (ESO) has discovered a planet orbiting Proxima. Not only that, it’s an Earth-like planet. And furthermore, it’s within Proxima’s habitable zone. This according to an unnamed source in a German newspaper.

The ESO is a highly respected, extremely trustworthy astronomical institution. As for unnamed sources… okay, let’s put our skeptical hats back on.

Let’s also remember that Earth-like planets are not necessarily all that Earth-like. For the last few weeks, I’ve been blogging from the surface of Titan, which is often described as one of the most Earth-like worlds in the Solar System. And let me tell you, it is miserable here. I guess there could be life on Titan, but not life as we humans understand it.

Mars is also sometimes described as Earth-like, and believe it or not, so is Venus.

Ag16 Earth-like Worlds

Supposedly the ESO will release its official findings at the end of August. Until then, we’ll just have to sit back, wait patiently, and stay skeptical.

P.S.: Ohmigod! Proxima Centauri might have… might… I can’t even! OH MY GOD!!!

Link

Earth-like Planet Around Proxima Centauri Discovered from Universe Today.