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.

****************************************

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.

****************************************

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 last week 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.

Last week's paper, 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.

***************************************

This week's Skeptophilia book recommendation is brand new, and is as elegiac as it is inspiring -- David Attenborough's A Life on Our Planet: My Witness Statement and a Vision for the Future.

Attenborough is a familiar name, face, and (especially) voice to those of us who love nature documentaries.  Through series such as Our Planet, Life on Earth, and Planet Earth, he has brought into our homes the beauty of nature -- and its desperate fragility.

At 93, Attenborough's A Life on Our Planet is a fitting coda to his lifelong quest to spark wonder in our minds at the beauty that surrounds us, but at the same time wake us up to the perils of what we're doing to it.  His message isn't all doom and gloom; despite it all, he remains hopeful, and firm in his conviction that we can reverse our course and save what's left of the biodiversity of the Earth.  It's a poignant and evocative work -- something everyone who has been inspired by Attenborough for decades should put on their reading list.

[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.