Eye of the storm

Ever heard of Wolf-Rayet stars?  They deserve more notice than they get, as one of the most violently energetic phenomena in the universe.  The fact that the name is not in common parlance -- when even the most scientifically-uninterested layperson has heard of supernovae and quasars and black holes -- is probably due to a combination of (1) their rarity, and (2) the fact that the ones that are visible to the naked eye are pretty unimpressive-looking at first glance.  Gamma Velorum and Theta Muscae, both of which are in the Southern Hemisphere and never visible where I live in upstate New York, are Wolf-Rayet stars that look completely ordinary until you check out their light spectra and find out that there's something really extraordinary going on.

The first thing that becomes apparent is that they are hot.  I mean, even by stellar standards.  Wolf-Rayet stars have a surface temperature between 30,000 K and an almost unimaginable 210,000 K.  (By comparison, the Sun's surface is about 5,700 K.)  These temperatures fuel an enormously strong stellar wind, which blows away almost all of the lightweight hydrogen in the outer layers, and also ionizes most of what is left -- predominantly oxygen, nitrogen, and carbon.  They're at the head of the list of potential gamma-ray bursters -- stars that undergo sudden collapse followed by a colossal explosion, resulting in a blast of gamma rays collimated into narrow beams along the star's rotational axis.  So having a Wolf-Rayet star's rotational axis pointed toward your planet would be like staring down the barrel of a loaded gun.

They're also beautiful.  At least from a distance.  The reason all this comes up is because of a paper in Monthly Notices of the Royal Astronomical Society about one that's been called "a stellar peacock" -- the star Apep, in the constellation Norma.  This Wolf-Rayet star has blown carbon-laden dust from its surface, which its high rotational speed swept into a pinwheel.

[Image licensed under the Creative Commons ESO/Callingham et al, The triple star system 2XMM J160050.7–514245 (Apep), CC BY 4.0]

The name Apep comes from Egyptian mythology -- Apep was the monstrous serpent who was the enemy of the god Ra.  Astronomer Joseph Callingham, one of the first to study Apep, thought the name was apt -- in his words it was "a star embattled within a dragon's coils."

All poetic license aside, the violent imagery is spot-on.  Wolf-Rayet stars eventually self-destruct, becoming black holes, but not until basically destroying anything unfortunate enough to be nearby.  So the bright spot at the center of Apep is the eye of a cosmic-scale storm.

The research I referenced, by a team led by University of Sydney student Yinuo Han, uses observational data from the Very Large Telescope in Chile to understand what is creating the spiral plumes.  The detail is phenomenal; in an interview with Science Daily, Han said, "The magnification required to produce the imagery was like seeing a chickpea on a table fifty kilometers away."

"[Wolf-Rayet stars] are ticking time bombs," said study co-author Peter Tuthill.  "As well as exhibiting all the usual extreme behavior of Wolf-Rayets, Apep's main star looks to be rapidly rotating.  This means it could have all the ingredients to detonate a long gamma-ray burst when it goes supernova."

It's hard to say anything about this group of stars without lapsing into superlatives.  "The speeds of the stellar winds produced are just mind-blowing," Han said.  "They are spinning off the stars at about twelve million kilometers an hour.  That's one percent the speed of light."

Fortunately for us, Apep is a safe 6,600 light years away, so it poses no danger to us.  If one was a lot nearer -- within 25 or so light years' distance -- it would be catastrophic.  The radiation bombardment could strip away the ozone layer, leaving the Earth's surface subject to massive irradiation.  There's decent evidence that some of the Earth's mass extinctions may have been caused by nearby supernovae (not necessarily Wolf-Rayets).  But to put your mind at ease, there aren't any supernovae candidates of any sort within what is rather terrifyingly called "the kill zone."

So that's a look at one of the most dangerous and beautiful phenomena in the universe.  I'm glad we're getting to see it, and find out a little bit about what makes it tick.

From a safe distance.

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Looking down the gun barrel

As regular readers of Skeptophilia know all too well, I have a fascination with things that are big and powerful and can kill you.

I've read book after book on earthquakes, tornadoes, and hurricanes.  I always told my students that if I hadn't become a mild-mannered science teacher, I'd have been a storm chaser, thus combining two of my favorite things -- meteorology, and things that are big and powerful and can kill you.

I suspect I am not alone in this.  Look at the common little-kid fascination with dinosaurs, and which ones tend to be the favorites -- not the peaceful herbivorous dinosaurs, but creatures like the T. rex and the Velociraptor and the Deinonychus, which would happily tear you limb from limb.  Look at disaster movies, stretching all the way back to such flicks as The Poseidon Adventure.  Look at Twister(s) and The Day After Tomorrow and Armageddon and The Perfect Storm.  Look, if you dare, at Sharknado.  What are they now up to, Sharknado 7 or something?

If not, they should be.

I think this is why there was an article in The Daily Mail called, "Death Rays From Space: Bursts of Energy From Black Holes Could Wipe Out Life on Earth WITHOUT Warning."  Which brings up a number of questions, the most important of which is, what kind of warning would you expect a black hole to give?  Do you think that a few hours before giving off a Burst of Energy, the black hole is going to post something on Twitter that says, "Beware!  I am about to wipe out all life on Earth!  #DeathRaysFTW  #SorryNotSorry"?

Be that as it may, it turns out that The Daily Mail actually got something right, an eventuality that ranks right up there with the fabled monkeys typing out the script to Hamlet.  There are stars which are capable of giving forth incredible amounts of energy in a very short amount of time.  They're called gamma-ray bursters, and are every bit as scary as they sound.  These things give off as much energy in a few seconds as the Sun will release in its entire ten billion year lifespan.  That, my friends, is what the astrophysicists refer to as "a shitload of energy."

And there's one only 7,500 light years away.  I say "only" not because that's an insignificant amount of distance, but because that's close enough that if the thing was aimed toward Earth and went off, we'd be fucked sideways.  Called Wolf-Rayet 104 (or WR-104 for short), it's a good candidate for a core-collapse supernova followed by a long-duration gamma-ray burst.

Of course, there's no particular reason to get all bent out of shape about it.  WR-104 is thought to stand a good chance of doing its thing not day after tomorrow, but some time in the next hundred thousand years.  And even then, it's pretty certain that the gamma-ray burst would be emitted in narrow jets from the magnetic poles of the star -- thus, it would only be a problem if we were literally looking right down the gun barrel, which most astronomers think we aren't.

WR-104 [Image is in the Public Domain courtesy of the Keck Telescope and NASA]

That, of course, doesn't stop The Daily Mail from waxing rhapsodic about how we're all gonna die, or at least get converted into the Incredible Hulk or something.  It's happened before, they say -- some scientists apparently think a gamma-ray burst is what caused the Ordovician extinction, 440 million years ago, that wiped out 85% of all marine life (although as we saw only a few days ago, there's another equally plausible claim that it was caused by a near pass by an asteroid).  It's only later in the article that they admit that the connection between the Ordovician extinction and a gamma ray burster is "impossible to prove," and even more reluctantly mention that "in a galaxy like ours, a gamma ray burst will happen once every million years, and it would need to be pointing in the right general direction to hit us...  So, are they going to kill us?  Probably not."

Is it just me, or do they sound... disappointed by this?  I would think that the idea that the Earth is unlikely to get fried by high-intensity gamma rays would be good news.  But I guess this goes back to what I started with; there's something about dangerous stuff that is inherently attractive.  The idea that the universe is big and scary makes us appreciate even more living in our safe houses, where we are very unlikely to be eaten by velociraptors.

Myself, I think it's the raw power that these kinds of things wield that is the source of the fascination.  I remember, as a kid growing up in southern Louisiana, there was something pretty exciting about being in the bullseye of a hurricane.  I distinctly recall standing in my parents' garage during the approach of Hurricane Carmen in 1974.   Just before closing the garage door and retreating inside, my dad and I watched in awe as tree branches and garbage cans flew through the air, rain fell sideways, and lightning struck every ten seconds.  It was scary but thrilling.  (The aftermath -- being without electricity for over a week, losing everything in the fridge and freezer, and cleaning up all of the damage -- was distinctly non-thrilling, but the storm itself was pretty exciting, at least to a kid.)

So there's some strange attraction to the dangerous things in the universe.  Even if for most of them, we'd like to observe from a safe distance.  Like gamma-ray bursters.

Not to mention sharknadoes.

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Stellar wind, the BOAT, and the Dragon's Egg

Since the news down here on Earth is not looking so good, today we're going to escape to my happy place, which is outer space.

We've got three new studies of fascinating astronomical phenomena to look at, the first of which comes out of the University of Vienna.  A team led by astrophysicist Kristina Kislyakova has, for the first time, directly detected stellar wind from three nearby Sun-like stars -- something which may effect the stability of the atmospheres of any planets orbiting them, and thus, their potential habitability.

Stellar wind -- which until now, we only knew about from studies of our own solar wind -- is a stream of particles given off by the upper atmosphere of stars, mainly composed of electrons, protons, and alpha particles with a kinetic energy of under 10 keV.  The solar wind is why comet tails always point away from the Sun (not, as many people erroneously think, simply the opposite of their direction of motion, like the wake of a boat).  Kislyakova's team looked for x-rays of specific frequencies coming from the three stars they studied (70 Ophiuchi, Epsilon Eridani, and 61 Cygni), because the stellar wind is expected also to contain small amounts of ionized oxygen, nitrogen, and carbon; as those ions are blown from the surface of the stars and ultimately slow down, they capture electrons, which drop into the atom's ground state and emit electromagnetic energy in the form of x-rays at particular frequencies.  From the amount of x-rays detected, they estimated the mass loss rate of the stars.

All three have much stronger stellar winds than the Sun does -- around 66, 16, and 10 (respectively) times the rate of mass loss from solar wind that the Sun experiences, which is itself considerable (estimated at 1.5 million metric tons per second).  The reason for the higher mass loss from the three stars studied is unknown -- but the Sun's calmer behavior is a good thing, because a strong stellar wind can peel away the atmosphere of exoplanets.  Any planets around 70 Ophiuchi, for example, are likely not to have much in the way of an atmosphere.

The second study is out of Northwestern University, and looked at something that has been nicknamed the BOAT (brightest of all time) -- a gamma-ray burst picked up in October of 2022 that saturated every gamma-ray detector on Earth.  It came from a source about 2.4 billion light years away in the constellation of Sagitta, and lasted for a few hundred seconds before starting to fade.  During that time it outshone the next-brightest observed gamma-ray burst by a factor of ten.

A team led by astrophysicist Peter Blanchard found that the BOAT was caused by a supernova -- but one acting very strangely.  The gamma-ray burst was so powerful that it took scientists some time to figure out that there even had been a supernova (imagine something so bright that it hides the light coming from a supernova!).  "The GRB was so bright that it obscured any potential supernova signature in the first weeks and months after the burst," Blanchard said.  "At these times, the so-called afterglow of the GRB was like the headlights of a car coming straight at you, preventing you from seeing the car itself.  So, we had to wait for it to fade significantly to give us a chance of seeing the supernova."

So why would an ordinary (if you can use that word) supernova cause such an enormous gamma-ray burst?  One possibility is that we might just be at the right place at the right time.  Models indicate that a rapidly-spinning massive star, when it reaches the end of its life, collapses into a black hole that gives off a a narrow jet of gamma rays aligned with the axis of its rotation.  It's possible that we just happened to be perfectly lined up with the black hole's axis -- looking right down the gun barrel, as it were.  But the fact is, they're still trying to figure that out, so we'll have to wait to see what more they learn.

The third study, led by astrophysicist Abigail Frost of the European Southern Observatory in Chile, looked at a strange and beautiful object nicknamed the "Dragon's Egg," in the southern constellation of Norma.

[Image credit: European Southern Observatory's Paranal Observatory in Cerro Paranal, Chile. ESO/VPHAS+/CASU/]

The curious thing about the pair of stars in the middle of the Dragon's Egg is that one of them has a magnetic field and the other doesn't.  Frost and her team believe that the same process that created the nebula surrounding them is what created the magnetic field in one of the stars.

It seems to be a case of stellar fratricide.  The more massive star in the binary pair is the one with the magnetic field, and the theory is that it used to be a triple star system -- but two of the stars underwent a merger.  The violence of that collision blew material out into space (the origin of the glowing dust cloud surrounding the remaining two stars) -- and the result dramatically increased the spin rate of the combined star, a bit like water speeding up as it goes down a drain.  Electrically-charged particles, such as those in stellar atmospheres, traveling in circles generate a magnetic field as per Maxwell's Laws, and that's why the more massive member of the surviving binary has such a powerful field.

So that's today's exploration of astronomical news.  Always makes me feel a bit tiny, when I consider phenomena out there in the depths of outer space.  Nothing wrong with that, of course -- humility is good.  And all in all, I'd rather be looking up than looking down in any case.

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An unusual outburst

There's something about the very large and the very small that never fails to be awe-inspiring.

I remember when my eighth grade science teacher was trying to impress upon us how tiny atoms were.  She asked us to think about how many atoms were in a typical raindrop.  Then she asked, "If you had the same number of grains of sand as there are atoms in a raindrop, how much sand would you have?"

The guesses were all over the place.  A bucket full.  A dump truck full.  A whole beach full.

But no, she said.  If you had as many grains of sand as there are atoms in a raindrop, you'd have enough to fill a trench a kilometer deep, three kilometers across...

... stretching all the way around the world at the equator.

I've since tried to do some ballpark estimation to see if this is right, and it appears to be pretty damn close.  If anything, it's an underestimate.

Then there's the world of the very large.  Voyager 1, one of the fastest spacecraft ever launched (hit speeds of 17 kilometers per second).  At those speeds, how long would it take to reach the nearest star other than the Sun -- Alpha Centauri?

Turns out it's 70,000 years.  The nearest star.  If it were heading that direction, which it's not.

Yeah, the universe we live in is a place of extremes.  But since we live in that middle zone in between, our brains aren't all that well-equipped to comprehend those extremes.  It doesn't take much before we simply boggle.  "Okay, that's small," or "okay, that's big," and we can't really get past that.  This, I think, is why the average U. S. citizen isn't all that concerned when (s)he hears that the federal deficit is now nudging close to one trillion dollars.

A trillion?  It's big.  That's a lot of money.  But so is a billion, and so is a million.

"Meh."  *shrugs shoulders*

I have to watch that tendency myself, and I consider myself at least above average at mathematics.  Which is why I had to do a little mental arithmetic when I read a paper published this week in Nature about one of the biggest, most powerful phenomena known -- a gamma-ray burster.

Artist's depiction of a gamma-ray burster [Image is in the Public Domain, courtesy of NASA/JPL]

Gamma-ray bursters are basically the death screams of enormous supergiant stars.  When one of those becomes a supernova, on its way to its final destination as a black hole, the shock waves from the explosion smash into the clouds of gas and debris moving outward from the star's surface, but traveling more slowly than the shock waves are.  This pumps energy into the gas clouds and triggers them to emit light.  Then the electrons freed by the collision slingshot even more energy into the light in a process called inverse Compton scattering.

The result is a jet of electromagnetic radiation like nothing else in the universe.  As spectacular as it is, it would be no fun to witness up close.  Any planet anywhere near -- and by near, keep in mind that I mean hundreds of light years -- would be flash-fried within milliseconds.

Here's something to wrap your head around.  One of the more familiar units of energy to science types is the electron volt.  What exactly it means, and why it's named that, isn't really critical here, but to give you a feel for it, your average photon of visible light carries with it an energy on the order of between one and three electron volts.

This week's paper describes the capture, by the two MAGIC (Major Atmospheric Gamma Imaging Cherenkov) Telescopes on the island of La Palma in the Canary Islands, of photons from a gamma-ray burster that carried one trillion electron volts of energy.  (There's no reason for concern, however.  The explosion in question took place 4.5 billion light years away, so by the time it got here, the energetic remnants were barely more than a blip.)

Here's another comparison, if that one wasn't enough for you.  Gamma-ray bursts of this type generally last between a few seconds and two minutes.  And in that time, more energy is released than the Sun will release in its entire lifetime.

At that point, my brain kind of goes into vapor lock and freezes up.  All I'm left with is the feeling of being very, very small.

Which is not necessarily a bad thing.  We humans tend to get a bit cocky at times, and it's good that sometimes we're reminded we're little fish in an extremely big pond.  The problems and day-to-day struggles we face down here are, in the grand scheme of things, insignificant.

On the other hand, I'm still pretty freakin' worried about the federal deficit.

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This week's Skeptophilia book recommendation is for people who have found themselves befuddled by such bizarre stuff as Schrödinger's Cat and the Pigeonhole Paradox and the Uncertainty Principle -- which, truthfully speaking, is probably the vast majority of us.

In Six Impossible Things: The Mystery of the Quantum World, acclaimed science writer John Gribbin looks at six possible interpretations of the odd results from quantum theory.  Gribbin himself declares himself a "quantum agnostic," that he is not espousing any one of them in particular.  "They all on some level sound crazy," Gribbin says.  "But in quantum theory, 'crazy' doesn't necessarily mean 'wrong.'"

His writing is clear, lucid, and compelling, and will give you an idea what the cutting edge of modern physics is coming up with.  It'll also blow your mind -- but isn't good science always supposed to do that?

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Looking down the gun barrel

I have to admit to a fascination with things that are big and powerful and can kill you.

I've read book after book on earthquakes, tornadoes, and hurricanes.  I've told my students that if I hadn't become a science teacher, I'd have been a storm chaser, thus combining two of my favorite things -- meteorology, and things that are big and powerful and can kill you.

I suspect I am not alone in this.  Look at the common little kid fascination with dinosaurs, and which ones tend to be the favorites -- not the peaceful herbivorous dinosaurs, but creatures like the T. rex and the Velociraptor and the Deinonychus, which would happily tear you limb from limb.  Look at the disaster movies, stretching all the way back to such flicks as The Poseidon Adventure.  Look at Twister and The Day After Tomorrow and The Perfect Storm.  Look, if you dare, at Sharknado.  What are they now up to, Sharknado 5 or something?

If not, they should be.

I think this is why a couple of days ago there was an article in The Daily Mail called, "Death Rays From Space: Bursts of Energy From Black Holes Could Wipe Out Life on Earth WITHOUT Warning."  Which brings up a number of questions, the most important of which is, what kind of warning would you expect a black hole to give?  Do you think that a few hours before giving off a Burst of Energy, the black hole is going to post something on Twitter that says, "Beware! I am about to wipe out all life on Earth! #DeathRaysFTW #SorryNotSorry"?

Be that as it may, it turns out that The Daily Mail actually got something right, an eventuality that ranks right up there with the fabled monkeys typing out the script to Hamlet.  There are stars which are capable of giving forth incredible amounts of energy in a very short amount of time.  They're called gamma-ray bursters, and are every bit as scary as they sound.  These things give off as much energy in a few seconds as the Sun will release in its entire ten billion year lifespan.  That, my friends, is what the astrophysicists refer to as "a shitload of energy."

And there's one only 7,500 light years away.  I say "only" not because that's an insignificant amount of distance, but because that's close enough that if the thing was aimed toward Earth and went off, we'd be fucked.  Called Wolf-Rayet 104 (or WR-104 for short), it's a good candidate for a core-collapse supernova followed by a long-duration gamma-ray burst.

Of course, there's no particular reason to get all bent out of shape about it.  WR-104 is thought to stand a good chance of doing its thing not day after tomorrow, but some time in the next hundred thousand years.  And even then, it's pretty certain that the gamma-ray burst would be emitted in narrow jets from the magnetic poles of the star -- thus, it would only be a problem if we were literally looking right down the gun barrel, which most astronomers think we aren't.

WR-104 [image courtesy of the Keck Telescope and NASA]

That, of course, doesn't stop The Daily Mail from waxing rhapsodic about how we're all gonna die, or at least get converted into the Incredible Hulk or something.  It's happened before, they say -- a gamma-ray burst is what caused the Ordovician extinction, 450 million years ago, that wiped out 85% of all marine life.  It's only later in the article that they admit that this conjecture is "impossible to prove," and even more reluctantly mention that "in a galaxy like ours, a gamma ray burst will happen once every million years, and it would need to be pointing in the right general direction to hit us... So, are they going to kill us?  Probably not."

Is it just me, or do they sound... disappointed by this?  I would think that the idea that the Earth is unlikely to get fried by high-intensity gamma rays would be good news.  But I guess this goes back to what I started with; there's something about dangerous stuff that is attractive.  The idea that the universe is big and scary makes us appreciate even more living in our safe houses, where we are very unlikely to be eaten by velociraptors.

Myself, I think it's the raw power that these kinds of things wield that is the source of the fascination. I remember, as a kid growing up in southern Louisiana, there was something pretty exciting about being in the bullseye of a hurricane.  I distinctly recall standing in my parents' garage during the approach of Hurricane Carmen in 1974.  Just before closing the garage door and retreating inside, my dad and I watched in awe as tree branches and garbage cans flew through the air, rain fell sideways, and lightning struck every ten seconds.  It was scary but thrilling.  (The aftermath -- being without electricity for two weeks, losing everything in the fridge and freezer, and cleaning up all of the damage was distinctly non-thrilling, but the storm itself was pretty exciting, at least to a kid.)

So there's some strange attraction to the dangerous things in the universe.  Even if for most of them, we'd like to observe from a safe distance.  Like gamma-ray bursters.

Not to mention sharknadoes.