Reach for the stars

A few days ago, I got an interesting email:

DO YOU WANT YOUR NAME TO BE REMEMBERED FOREVER?

With the Hubble Space Telescope and the James Webb Telescope discovering new stars and planets and galaxies every single day, the astronomers can't keep up with naming them.  So many of them end up with strings of numbers and letters that no one can ever remember.  How much better would it be to have a heavenly body named after YOU?  Or your loved one?  Or your favorite pet?

We are the STAR REGISTERY [sic] SERVICE, where you can choose from thousands of unnamed stars, and give it whatever name you choose.  You will receive a beautiful framable certificate of ownership with the location (what the astronomers call the Declination and Right Ascension) of your OWN PERSONAL STAR so you can go outside any clear night and find it.  

A lovely idea for a gift -- or a gift to yourself!

We then are told that the fee for this service is a paltry $40 U.S., and that they accept PayPal, Venmo, and major credit cards.  And it's accompanied by this enticing and irresistible photo:

Okay, there are a few problems with this.

First, I can think of a great many better uses for forty bucks, and that includes using it to start a campfire.  Part of this is that I'm a major skinflint, but still.

Second, the vast majority of the "new stars and planets and galaxies" catalogued by the Hubble and JWST are far too faint to see with the naked eye, so I wouldn't be able to go outside on a clear night and see "my own personal star" unless I happened to bring along the Palomar Telescope.  So the most I could do is to find the approximate location, and try to gain some sense of ownership by staring up into the dark.

Third, what on earth does it mean to claim that I "own a star?"  The nearest star (which, so far as I know, is not for sale) is about forty trillion kilometers away, so unless warp drive is invented soon (not looking likely), I'll never go to visit my star.  And doesn't selling something imply that the seller owned it to start with?  I doubt seriously whether the "Star Registery Service" could demonstrate legal ownership of any of the things out there in space that they're trying to sell.

So needless to say, I'm not going to pay forty dollars for a piece of paper, however "beautiful" and "framable" it is.  If I gave it as a present to my wife, she would roll her eyes enough to see the back of her own skull.  And I'm not naming a star after my puppy.  Jethro is a lovely little dog, but smart, he isn't.  He seems to spend his entire existence in a state of mild puzzlement.  Anything new is met with an expression that can be summed up as, "... wait, what?"  So appreciating the wonders of astrophysics is kind of outside his wheelhouse.  (Pretty much everything is outside his wheelhouse other than playing, snuggling, sleeping, and eating dinner.)

But I digress.

So anyway, I didn't respond to the email.  But because I live for investigating the weird corners of human behavior -- and also because I never met a rabbit-hole I didn't like -- I started poking around into other examples of people claiming to own astronomical objects.  And this, it turns out, has a long and storied history.  Here are just a few examples I found out about:

• In 1996, a German guy named Martin Juergens claimed that he owned the Moon.  On 15 July 1756, Juergens said, German emperor Frederick the Great deeded the Moon to his ancestor Aul Juergens, and it passed down through the family, always being inherited by the youngest son.  Needless to say, pretty much no one took him seriously, although apparently he believes it himself.
• Back in 1936 the Pittsburgh Notary Public received a banker's check and a deed for establishment of property filed by one A. Dean Lindsay, wherein he claimed the ownership of all extraterrestrial objects in the Solar System.  Lindsay had earlier submitted claims of ownership on the Atlantic and Pacific Oceans, but these were both denied.  The extraterrestrial objects one, though, was apparently notarized and filed, with the Notary Public taking the attitude that if the dude wanted to spend money for something he couldn't ever get to, that was on him.  Lindsay got the last laugh, however, when he was approached multiple times by other even loonier people who wanted to buy specific extraterrestrial objects from him.  Lindsay was happy to sell.  At a profit, of course.
• When NASA landed the NEAR Shoemaker probe on the asteroid 433 Eros in 2001, they were promptly served with a bill for twenty dollars from Gregory Nemitz, who claimed he owned it and they owed him for parking.  NASA unsurprisingly refused to pay.
• Nemitz wasn't the only one to trouble NASA with claims of ownership.  In 1996 three Yemeni men, Adam Ismail, Mustafa Khalil, and Abdullah al-Umari, sued NASA for "invading Mars."  They said they had inherited the planet from their ancestors three thousand years ago.  Once again, NASA declined to make reparations.
• In 1980, an entrepreneur named Dennis Hope started a company called the Lunar Embassy Commission, which sells one-acre plots on the Moon for twenty dollars each.  (It'd be fun to put him and Martin Juergens in a locked room and let them duke it out over whose property the Moon actually is.)  Once he gets your money, he chooses your plot by randomly pointing to a lunar map with a stick, which seems kind of arbitrary; at least the "Star Registery Service" was gonna let me pick my own star.  Despite this, he claims that former presidents Jimmy Carter and Ronald Reagan were both customers.
• Lastly, in the Go Big Or Go Home department, we have noted eccentric James T. Mangan (1896–1970), who publicly claimed ownership of all of outer space in 1948.  He founded what he called the Nation of Celestial Space (also known as "Celestia") and registered it with the Cook County, Illinois, Recorder of Deeds and Titles on 1 January 1949.  At its height in 1960 the Nation of Celestial Space had almost twenty thousand, um, "residents," but since Mangan's death in 1970 it has more or less ceased to exist as an official entity.  Space itself, of course, is still out there, and seems unaffected by the whole affair.

Anyhow, I think I'll pass on star ownership.  (Or Moon, or Mars, or outer space, or whatnot.)  The whole thing strikes me as a little ridiculous.  Of course, if I think about it too hard, even our concept of owning land down here on Earth is pretty goofy; what does it mean to say I own this parcel of property, when it was here before I was born and will still be here long after I'm gone?  Okay, I can use it to live on; ownership gives me certain rights according to the laws of New York State.  I get that.  But honestly, even the concept of dividing up the Earth using (mostly) arbitrary and invisible lines, and saying stuff is legal on one side of the line and illegal on the other side, is weird, too.  (And don't even get me started about how to cross certain invisible lines, you need a special piece of paper, and if you don't have it and try to cross anyhow, mean people get to shoot you.)

You have to wonder what would happen if the intelligent creatures out there who come from those far distant star systems traveled here, and I tried to tell them, "See, your star, I bought that for forty dollars from some guy on the internet."  My guess is they'd vaporize me with their laser pistol and head back out into space after stamping their map of the Solar System with the words "No Intelligent Life Present."

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Vanishing act

In Madeleine L'Engle's seminal young-adult fantasy novel The Wind in the Door, there's something that is making the stars go out.

Not just stop shining, but disappear entirely.  Here's the scene where the protagonist, Meg Murry, first witnesses it happening:

The warm rose and lavender of sunset faded, dimmed, was extinguished.  The sky was drenched with green at the horizon, muting upwards into a deep, purply blue through which stars began to appear in totally unfamiliar constellations.

Meg asked, "Where are we?"

"Never mind where.  Watch."

She stood beside him, looking at the brilliance of the stars.  Then came a sound, a violent, silent, electrical report, which made her press her hands in pain against her ears.  Across the sky, where the stars were clustered as thickly as in the Milky Way, a crack shivered, slivered, became a line of nothingness.

Within that crack, every star that had been there only a moment ago winked out of existence.

A central point in the story is that according to the laws of physics, this isn't supposed to happen.  Stars don't just vanish.  When they end their lives, they do so in an obvious and violent fashion -- even small-mass stars like the Sun swell into a red giant, and eventually undergo core collapse and blow off their outer atmospheres, creating a planetary nebula.  

The Cat's Eye Nebula [Image is in the Public Domain courtesy of NASA/JPL and the ESO]

Larger stars end their lives even more dramatically, as supernovas which lead to the formation of a neutron star or a black hole depending on how much matter is left over once the star blows up.

Well, that's what we thought always happened.

A study out of the University of Copenhagen has found that like in A Wind in the Door, sometimes stars simply... vanish.  A team of astrophysicists has found that instead of the usual progression of Main Sequence > Giant or Supergiant > BOOM! > White Dwarf, Neutron Star, or Black Hole, there are stars that undergo what the astrophysicists are (accurately if uncreatively) calling "complete collapse."  In a complete collapse, the gravitational pull is so high that even considering the power of a supernova, there's just not enough energy available for the outer atmosphere to achieve escape velocity.  So instead of exploding, it just kind of goes...

... pfft.

Unlike what Meg Murry witnessed, though, the matter that formed those stars is still there somewhere; the Law of Conservation of Matter and Energy is strictly enforced in all jurisdictions.  The star that was the focus of the study, VFTS 243, is part of a binary system -- and its companion star continued in its original orbit around their mutual center of mass without so much as a flutter, so the mass of its now-invisible partner is still there.  But the expected cataclysmic blast that usually precedes black hole formation never happened.

"We believe that the core of a star can collapse under its own weight, as happens to massive stars in the final phase of their lives," said Alejandro Vigna-Gómez, who co-authored the study.  "But instead of the contraction culminating into a bright supernova explosion that would outshine its own galaxy, expected for stars more than eight times as massive as the Sun, the collapse continues until the star becomes a black hole.  Were one to stand gazing up at a visible star going through a total collapse, it might, just at the right time, be like watching a star suddenly extinguish and disappear from the heavens.  The collapse is so complete that no explosion occurs, nothing escapes and one wouldn't see any bright supernova in the night sky.  Astronomers have actually observed the sudden disappearance of brightly shining stars in recent times.  We cannot be sure of a connection, but the results we have obtained from analyzing VFTS 243 has brought us much closer to a credible explanation."

You can see why I was immediately reminded of the scene in L'Engle's book.  And while I'm sure the answer isn't evil beings called Echthroi who are trying to extinguish all the light in the universe, the actual phenomenon is still a little on the unsettling side.

Once again showing that we are very far from understanding everything there is out there.  This sort of vanishing act has been high on the list of Things That Aren't Supposed To Happen.  It'll be interesting to see what the theorists propose with when they've had a shot at analyzing the situation, and if they can come up with some sort of factor that determines whether a massive star detonates -- or simply disappears.

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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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Aurora stellaris

Today's topic falls into the category of "The More You Think About It, The Weirder It Gets," and comes to us courtesy of my writer friend Andrew Butters.

Before I get to the meat and potatoes of the story, two bits of background.

Auroras occur because of the solar wind, a powerful stream of particles (chiefly electrons and protons) emitted from the upper atmosphere of the Sun.  When they strike the Earth's upper atmosphere and interact with the various molecules in the air, this has the effect of exciting the electrons in the molecules (bouncing them to higher energy levels), and when those electrons fall back into the ground state, they emit the extra energy as light.  Because of the quantization of energy levels, each color (frequency) is associated with a particular transition in a particular element -- the commonest are reds and greens (from oxygen) and blues (from nitrogen).

Auroras on Earth are most often seen in high latitudes because of the shape of the Earth's magnetic field.  The slope of the magnetic field lines increases the closer you get to the poles, so at high latitudes it acts a bit like a funnel, creating spectacular displays in the Arctic and Antarctic regions.

Despite the fact that I feel like I feel like I live in the Frozen North (especially at this time of year), I've only ever gotten to see the auroras once.  It was about ten years ago, and we heard there was a solar storm and the "Northern Lights" were going to be seen a lot farther south than usual.  That night it was supposed to be crystal-clear -- also an unusual occurrence in this cloudy climate -- so once it was dark, my wife and I went across the street into the neighbor's field and watched for a while, with disappointing results of the "Is that a flicker?  I think that's a flicker" sort.

At some point my wife, who is clearly the brains of the operation, realized that we were looking for the Northern Lights, but we were facing south.  In our defense, there were fewer trees obstructing the sky in that direction, but it's still a little like the guy who was searching around the kitchen floor for his contact lens, and his wife joined him, but the two of them couldn't find it.  She finally said, "Are you sure you dropped it in the kitchen?"  And he responded, "No, I dropped it in the bathroom, but the light is better in here."

In any case, we turned around to the north...

.... and wow.

Over our rooftop and beyond the branches of the walnut trees was a light show like I've never seen before -- shifting curtains of green luminescence resembling some kind of gauzy emerald curtain.  It was spectacular.  We watched it for about forty-five minutes before it finally started to fade.

So if you're ever looking for auroras, make sure you're pointed the right way.

The second piece of background is that there is a strange astronomical object called a brown dwarf.  Brown dwarfs are almost-stars -- something on the order of twenty to eighty times the mass of the planet Jupiter.  Since the fusion of hydrogen into helium -- what powers stars' cores -- requires intense pressure to get started, there's a lower limit to the mass a star can have.  Below that mass, the gravity of its contents is insufficient to raise the pressure in the core to the point where fusion can begin, and what you end up with is something midway between a planet and a star.

Well, the link Andrew sent me is about a new discovery by the amazing James Webb Space Telescope -- of a brown dwarf, W1935, which has auroras.

On first glance, you might think, "why not?"  But remember how auroras are created.  They're caused by the interaction of a stream of high-energy particles with the atmosphere of a planet.

So where are the high-energy particles coming from?

Artist's illustration of W1935 [Image courtesy of artist Leah Hustak and NASA/ESA/CSA]

Even odder, the atmosphere of W1935 seems to have a temperature inversion -- a region of the atmosphere that warms, rather than cools, with increasing altitude.  Its upper atmosphere was glowing with the very specific infrared frequency given off when you heat methane.  So not only does it have auroras when there's no reason it should, there's some sort of a heat source that's creating convection in its atmosphere without it receiving an external heat input from a star.

"We expected to see methane, because methane is all over these brown dwarfs. But instead of absorbing light, we saw just the opposite: The methane was glowing," said Jackie Faherty, of the American Museum of Natural History, who led the study.  "My first thought was, what the heck?  Why is methane emission coming out of this object?...  With W1935, we now have a spectacular extension of a solar system phenomenon without any stellar irradiation to help in the explanation.  With the JWST, we can really 'open the hood' on the chemistry and unpack how similar or different the auroral process may be beyond our solar system."

So here we have one more example of a significant mystery out there in space, and yet another brilliant contribution to astronomy and astrophysics by the JWST.  It seems like every new cache of data opens up as many new questions as it solves old ones.  But that's the way it goes with science -- as Neil deGrasse Tyson put it, "As the area of our knowledge grows, so too does the perimeter of our ignorance."

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Kablooie

I'm kind of an excitable type.

I think that may be why I went into science.  The rigorous, evidence-basted methods of science were a nice antidote to the fact that my natural state is having my emotions swinging me around by the tail constantly.

Even after years of studying (and teaching) science, and twelve years of writing about it here at Skeptophilia Central, I still have the capacity for going off the deep end sometimes.  Which is what happened when I read a paper (a preprint, actually) from the Monthly Notices of the Royal Astronomical Society called "The Evolutionary Stage of Betelgeuse Inferred from its Pulsation Periods," by Hideyuki Saio (Tohoku University) and Devesh Nandal, Georges Meynet, and Sylvia Ekström (Université de Genève).

The constellation Orion.  Betelgeuse is in the upper left corner of the image.  [Image licensed under the Creative Commons Mouser, Orion 3008 huge, CC BY-SA 3.0]

First, a little background, before I get to the squee-inducing part.

Stars exist in a state of tension between two forces -- the inward pull of gravity and the outward pressure from the heat produced by fusion in the core.  At the very beginning of their lives, stars form from a loose cloud of mostly hydrogen gas that collapses under its own attractive gravitational force.  That collapse increases the pressure and temperature, and -- if the initial cloud was big enough -- eventually they rise high enough to trigger the fusion of hydrogen atoms into helium.  This is a (very) energy-releasing reaction -- physicists call such reactions exothermic -- and that energy pushes outward, balancing the inward pull of gravity.  The star goes into equilibrium.

But there's not an infinite supply of hydrogen.  The hydrogen fuel in the core is eventually exhausted, so fusion slows down.  The temperature drops, as does the outward pressure, so -- for a while -- gravity wins.  The star collapses, heating the core up, until the temperature and pressure become sufficient to fuse the helium "ash" in the core into carbon.  (This process, incidentally, is where the carbon in the organic molecules in our bodies comes from; Carl Sagan was spot-on in saying "We are made from star stuff.")

Helium fusion is also exothermic, so once again, the star goes into equilibrium.  But then the helium runs out, and the collapse resumes until the pressure and temperature are high enough to fuse carbon into oxygen. 

Then oxygen into silicon.  Then silicon into iron.

Two things are important here.  The first is that each of the reactions -- from hydrogen fusing into helium through silicon fusing into iron -- produces less energy than the one before it but requires higher temperatures and pressures to make it happen.  The second is that something happens when you pass that final reaction, which is that any subsequent fusion into heavier elements is an endothermic, or energy-consuming, reaction.

So when the silicon is used up, and the star's core is made mostly of iron, there's pretty much nowhere to go.  The gravitational collapse picks up again, and there is no "next reaction" that might produce energy to balance it.  So the collapse continues until finally there's such a tremendous temperature spike that the entire star goes kablooie.

This is called a supernova, and it releases more energy in a few seconds than the star liberated in the entire rest of its life.  The unimaginable pressures do fuse some of the iron in the core into those heavier elements, despite the energy required, and that's where all the elements on the periodic table with atomic numbers higher than 26 come from, from the gold in our jewelry to the silver in our coinage and the copper in our electrical wires.

With me so far?  Because there's one more thing I haven't told you.

Each stage in a star's life takes much less time than the one before it.

The hydrogen to helium stage lasts millions to billions of years.  (The Sun is in the hydrogen-burning stage, and is estimated to have another five billion years to go.)  Higher-mass stars have higher pressures and temperatures, and consume their fuel at a greater rate, but we're still talking tens to hundreds of millions of years.  Helium-to-carbon lasts maybe a million years; carbon-to-oxygen, we're talking decades.

After that, it's pretty much a ticking time bomb with a very short fuse.

Now for the punch line: the Saio et al. paper suggests that the pulsation periods of the red supergiant star Betelgeuse indicate that it is nearing the end of the carbon burning stage.  So we might actually have a shot at seeing one of the brightest stars in the sky go supernova in our lifetimes.

This paper has even the scientists flipping out.  One of my favorite science vloggers, astronomer Becky Smethurst of Oxford University, did a YouTube video about this paper and you could tell she was barely keeping it together.  Ordinarily, whenever you hear about anything impressive in sciences like astronomy and geology -- such as a supernova or gamma-ray burster, or the Yellowstone Supervolcano erupting or the East African Rift Zone tearing Africa apart -- the scientists will respond with a deep sigh and a monotone "as we've explained many times before, blah blah blah astronomical/geological time scales blah blah blah."

Now, though, the astronomers are actually acting like this is the real deal.  (And in fact, if Saio et al. are right, Betelgeuse has probably already blown itself to smithereens; at six-hundred-odd light years away, we just haven't gotten the memo yet.)

When this happens, it's gonna be spectacular.  A supernova that close will be bright enough to read by at night, most likely for months, and will be easily visible during the day.  The happy news is that it's not close enough to do us any damage; a supernova under twenty-five light years away could be catastrophic, doing nasty stuff like blowing away the atmosphere.  (Fortunately, there are no supernova candidates anywhere near that close to us.)  Betelgeuse will just create some amazing fireworks, as well as permanently changing the contour of the familiar constellation of Orion.

So my opinion is: bring on the supernova.  We could use a little excitement down here.

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Fish star

Fomalhaut is the brightest star in the southern constellation of Piscis Austrinus, the Southern Fish.  At a declination (stellar latitude) of −29° 37′, it's seldom visible where I live, but I did get a good look at it when I was in Ecuador a few years ago.  It's bright -- a first-magnitude star -- but looked brighter because of the elevation; when you're up in the mountains, on a clear night it's hard to recognize constellations because there are so many visible stars.

The star's odd moniker comes directly from the Arabic Fom al-Haut, "the mouth of the whale."  As always, though, other cultures saw it differently.  The Chinese gave it the fanciful name Běiluòshīmén, meaning "the north gate of the military camp."  To the Persians it was Hastorang, one of the "Four Royal Stars."  (The other three were Aldebaran, Regulus, and Antares.)  It seems to have had some significance to indigenous Americans; the two-thousand-year-old Earthwork B, in Mounds State Park in Indiana, seems to line up with the rising of Fomalhaut, but the reason is unknown.  To the Moporr, an indigenous people in South Australia, it was a powerful male deity named Buunjill.  Not to be outdone, in the Lovecraftian mythos Fomalhaut is the home of the Great Old One Cthugha, who appeareth unto mankind as a fiery sphere and basically scareth the absolute shit out of everyone who seeeth him.

More prosaically, though, Fomalhaut is interesting to astronomers as the eighteenth brightest star in the sky overall, and the third brightest star known (or thought) to have a planetary system (after the Sun and Pollux).  It's young, something on the order of four hundred million years old.  (I know that seems pretty damn old, but keep in mind that the Sun is over ten times older than that.)  It's a Type A star, which doesn't mean that it's hard-working and tightly-wound, but that it's blue-white in color and has strong emission lines from hydrogen and ionized metals.  (Another, better known, Type A star is Vega, made famous as the home system of the aliens in the wonderful movie Contact.)

What's coolest about this star, though -- and the reason it comes up today -- is its ring of dust and debris, which was photographed directly in 2012 by ALMA (the Atacama Large Millimeter/submillimeter Array):

[Image licensed under the Creative Commons LMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope ; Acknowledgement: A.C. Boley et al., ALMA observes a ring around the bright star Fomalhaut, CC BY 4.0]

The James Webb Space Telescope just got even more detail; it was able to discern not only the outer ring of debris but an inner ring, comparable to the Sun's Kuiper Belt and Asteroid Belt, respectively. which suggests to astrophysicists that there are planets gravitationally "herding" the debris into rings, just as Neptune and Jupiter do for our two belts.

"I would describe Fomalhaut as the archetype of debris disks found elsewhere in our galaxy, because it has components similar to those we have in our own planetary system," said András Gáspár of the University of Arizona in Tucson, lead author of the paper, which appeared in Nature Astronomy last week.  "By looking at the patterns in these rings, we can actually start to make a little sketch of what a planetary system ought to look like -- if we could actually take a deep enough picture to see the suspected planets."

"Where Webb really excels is that we're able to physically resolve the thermal glow from dust in those inner regions," said Schuyler Wolff, also of the University of Arizona in Tucson, who co-authored the paper.  "So you can see inner belts that we could never see before.  We definitely didn't expect the more complex structure with the second intermediate belt and then the broader asteroid belt.  That structure is very exciting because any time an astronomer sees a gap and rings in a disk, they say, 'There could be an embedded planet shaping the rings!'"

Or, you know, a Lovecraftian Elder God creating a fire vortex in the eldritch nether regions of the void.  You know how it goes.

In any case, it's incredibly cool to see what's coming in from the JWST.  Here, we're seeing a system that might be a little like what the Solar System looked like four billion years ago, as the planets were coalescing from the rocky debris of the protoplanetary disk.  The astronomers, of course, are going to give it a much closer look.  "The belts around Fomalhaut are kind of a mystery novel: Where are the planets?" said George Rieke, of the JWST's Mid-Infrared Instrument (MIRI) team, who also co-authored.  "I think it's not a very big leap to say there's probably a really interesting planetary system around this star."

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Off the chart

Way back around 1910, Danish astronomer Ejnar Hertzsprung and American astronomer Henry Norris Russell independently found a curious pattern when they did a scatterplot correlation between stars' luminosities and temperatures.

The graph, now called the Hertzsprung-Russell Diagram in their honor, looks like this:

[Image licensed under the Creative Commons Richard Powell, HRDiagram, CC BY-SA 2.5]

Most stars fall on the bright swatch running from the hot, bright stars in the upper left to the cool, dim stars in the lower right; the overall trend for these stars is that the lower the temperature, the lower the luminosity.  Stars like this are called main-sequence stars.  (If you're curious, the letter designations along the top -- O, B, A, F, G, K, and M -- refer to the spectral class the star belongs to.  These classifications were the invention of the brilliant astronomer Antonia Maury, whose work in spectrography revolutionized our understanding of stellar evolution.)

There is also a sizable cluster of stars off to the upper right -- relatively low temperatures but very high luminosities.  These are giants and supergiants.  In the other corner are white dwarfs, the exposed cores of dead stars, with very high temperatures but low luminosity, which as they gradually cool slip downward to the left and finally go dark.

So there you have it; just about every star in the universe is either a main-sequence star, in the cluster with the giants and supergiants, or in the curved streak of dwarf stars at the bottom of the diagram.

Emphasis on the words "just about."

One star that challenges what we know about how stars evolve is the bizarre Stephenson 2-18, which is in the small, dim constellation Scutum ("the shield"), between Aquila and Sagittarius.  At an apparent magnitude of +15, it is only visible through a powerful telescope; it was only discovered in 1990 by American astronomer Charles Bruce Stephenson, after whom it is named.

Its appearance, a dim red point of light, hides how weird this thing actually is.

When Stephenson first analyzed it, he initially thought what he was coming up with couldn't possibly be correct.  For one thing, it is insanely bright, estimated at a hundred thousand times the Sun's luminosity.  Only its distance (19,000 light years) and some intervening dust clouds make it look dim.  Secondly, it's enormous.  No, really, you have no idea how big it is.  If you put Stephenson 2-18 where the Sun is, its outer edge would be somewhere near the orbit of Saturn.  You, right now, would be inside the star.  Ten billion Suns would fit inside Stephenson 2-18. 

If a photon of light circumnavigated the surface of the Sun, it would take a bit less than fifteen seconds.  To circle Stephenson 2-18 would take nine hours.

This puts Stephenson 2-18 almost off the Hertzsprung-Russell Diagram -- it's in the extreme upper right corner.  In fact, it's larger than what what stellar evolution says should be possible; the current model predicts the largest stars to have radii of no more than 1,500 times that of the Sun, and this behemoth is over 2,000 times larger.

Astronomers admit that this could have a simple explanation -- it's possible that the measurements of Stephenson 2-18 are overestimates.  But if not, there's something significant about stellar evolution we're not understanding.

Either way, this is one interesting object.

There's also a question about what Stephenson 2-18 will do next.  Astrophysicists suspect it might be about to blow off its outer layers and turn either into a luminous blue variable or a Wolf-Rayet star (the latter are so weird and violent I wrote about them here a while back).  So it may not be done astonishing us.

Puts me in mind of the quote from Richard Dawkins: "The feeling of awed wonder that science can give us is one of the highest experiences of which the human psyche is capable."

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A cataclysmic pirouette

Hamlet famously states to his friend, "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy," and every time we look into the night sky, we're reminded how true that is.

In the last hundred years astronomers have discovered deadly gamma-ray bursters and black holes, neutron stars for which a teaspoon of their material would weigh as much as a mountain, planets made of stormy swirls of ammonia, methane, and hydrogen, ones made of super-hot molten metal, water-worlds completely covered with deep oceans.  We've seen newborn stars and stars in their violent death throes, looked out in space and back in time to the very beginning, when the universe itself was in its infancy.

Even with all these wonders, new and bizarre phenomena are still being discovered every time our technology improves.  Take, for example, the "cataclysmic variable" that was the subject of a paper in Nature this week, a pair of stars locked in such a tight dance that they whirl around their common center of gravity in only fifty-one minutes.

Given the euphonious name ZTF J1813+4251, this pair of stars is comprised of a white dwarf -- the burnt-out core of a low-mass star like the Sun -- and an even more lightweight star not much bigger than the planet Jupiter.  The white dwarf has been swallowing (the astronomical term is "accreting") the hydrogen fuel from its partner, and they're drawing closer together, meaning that the process will speed up.  Eventually all that will be left of the partner star will be its core, and astronomers predict that at that point, they will have an orbital period of eighteen minutes.  But once the accretion process ends, drag in the pair's movement will rob energy from the system, the wild stellar pirouette will slow down, and they will gradually start to move apart again.

It's fortunate that the partner star is as light as it is; if it had more mass, it would be headed toward one of the most violent fates a star can have -- a type 1a supernova.  White dwarfs are the remnants of stars that have exhausted all their fuel, and they shrink until the inward pull of gravity is counterbalanced by the mutual repulsion of the negatively-charged electrons that surround the atoms they're made of.  There's a limit, though, to how much this repulsive force can withstand; it's called the Chandrasekhar limit, after its discoverer Subrahmanyan Chandrasekhar, and is equal to 1.44 solar masses.  For a lone white dwarf -- as our Sun will one day be -- this is not a problem, as there won't be anything substantial adding to its mass after it reaches that point.

The situation is different when a low-mass star is in a binary system with a giant star.  When the low-mass star burns out and becomes a white dwarf, it begins to rob its partner of matter -- just as ZTF J1813+4251 is doing.  But in this case, there is a lot more mass there to rob.  Eventually, the white dwarf steals enough matter from its companion to go past the Chandrasekhar limit, and at that point, the mutual repulsion of the electrons in the stars atoms lose their contest with the inward pull of gravity.  The white dwarf's core collapses completely, making the temperature skyrocket so high that its helium ash can fuse into carbon and other heavier elements, suddenly releasing catastrophic amounts of energy.  The result is...

... boom.

In the process, the matter from the exploded dwarf star is scattered around the cosmos, and becomes the parent material for forming planets.  It is, in fact, how most of the carbon, oxygen, and nitrogen in our bodies were formed.

As Carl Sagan famously said, "We are made of starstuff."

A type 1a supernova remnant [Image is in the Public Domain courtesy of NASA/JPL]

But ZTF J1813+4251 isn't headed for such a dramatic exit -- eventually the white dwarf will pull away the outer layers of the partner star's atmosphere, and after that the two will just spiral around each other wildly for a few million years, gradually cooling and slowing from their current frenetic pace.  So maybe "cataclysmic" isn't the right word for this pair; their crazy tarantella will simply wind down, leaving two cold clumps of stellar ash behind.

Honestly, if I were a star, I think I'd rather go out with a bang.

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A window on deep time

The ultimate speed limit in the universe -- unbreakable, as far as our current understanding of science goes -- is the speed of light, 3x10^8 meters per second.

Most people think of spaceships when this comes up, and certainly it's easy to conceptualize this in terms of objects moving.  What might be less intuitive is that this speed limit also applies to the movement of information.  If an event occurs, the soonest we can know about it is the amount of time it takes for light to get from there to here.  So -- to use an oft-cited, if a little ridiculous, example -- if the Sun were to disappear, we wouldn't know about it for 8.317 minutes, because the Sun is 8.317 light-minutes from Earth.

So we're always looking into the past, and the farther away something is, the farther into the past we're looking.  You see the Sun as it was a little over eight minutes ago.  The distance between the Earth and Mars varies, given that both are in elliptical orbits around the Sun and moving at different angular velocities, but on average Mars is a bit under thirteen light-minutes from us, which is why the Mars rovers had to be able to sense their environment and function independently.  If here on Earth we saw through its camera that the rover was heading toward the edge of a cliff, and we sent a message saying "Stop!  Turn around!", it would be far too late.  Not only would that image have taken (again, on average) thirteen minutes to get to us, it would take another thirteen minutes for our command to get back to it.  By that time, it would be a heap of scrap metal on the bottom of the cliff.

And so on.  We see the nearest star to the Sun, Proxima Centauri, as it was 4.3 years ago.  The brightest star in the night sky, Sirius, in the constellation of Canis Major, is 8.6 light years away.  Vega, brightest star in the constellation Lyra -- the one made famous as the home of the super-intelligent aliens in the movie Contact -- is twenty-five light years away.  When we see the other side of our own galaxy, we're seeing what it looked like around a hundred thousand years ago (at which point we were in the middle of an ice age, and our distant ancestors were just on the point of leaving the African savanna).  The nearest galaxy to the Milky Way, the Andromeda Galaxy, is 2.5 million light years away -- when the light from it left its source, there weren't any modern humans, and the species Homo habilis had just mastered the use of tools.

But this ultimate speed limit means there's also a limit to how far away we can see.  The Big Bang is estimated to have happened 13.8 billion years ago, so the Cosmic Microwave Background Radiation -- the remnant radiation from only a short time after the universe formed -- has been traveling toward us for 13.8 billion years, and represents the most distant thing it's even theoretically possible to see.  There is certainly stuff farther away from us than that; for one thing, in the intervening 13.8 billion years, the universe has been continuously (although not uniformly) expanding, so the radius of the universe is way bigger than 13.8 billion light years.  But whatever is farther away than that is completely out of our reach, no matter how good our telescopes get.  Our knowledge of anything beyond the distance limit imposed by the speed of light is zero, and always will be.

That doesn't mean we can't see a long way, though.  Last week in Nature it was announced that the Hubble Space Telescope had captured a photograph of the most distant star ever seen, at 12.9 billion light years away.  The image was distorted by gravitational lensing, when the light from a luminous object passes through a region of space warped by a large mass, but the astronomers are saying the source is too small to be a galaxy or star cluster.  We know how far away it is because of its red shift, the stretching of the wavelength of light when its source is moving away from us, combined with Hubble's Law, which connects the amount of red shift with the object's distance.

The image containing Earendel [Image is in the Public Domain courtesy of NASA/JPL]

The astronomers named the star Earendel -- an Old English word meaning "morning star."  If you immediately thought of J. R. R. Tolkien when you saw this, so did I; the name of the character Eärendil in The Silmarillion was pilfered directly from Old English, of which Tolkien was a noted scholar.  Tolkien said he was struck by the word's "great beauty," and adopted it into his conlang Quenya (one of the Elvish languages in his stories).  In Quenya, Eärendil means "lover of the sea," but interestingly, at the end of The Silmarillion, when Morgoth is defeated, the last remaining Silmaril -- the phenomenally beautiful jewels created by the Elf Fëanor, that were the cause of the entire conflict in the book -- is taken by Eärendil up into the sky, where it becomes the "morning star," or Venus.  So the myth and Tolkien's story come full circle.

In any case, the fact that we can see something that far away is kind of astonishing.  When the light Hubble captured from Earendel left its surface, it was 8.4 billion years before the Earth would form.  In fact, Earendel almost certainly doesn't exist any more; the current guess is that it is (or was) a supergiant, meaning it had high temperatures and luminosity, and would have burned through its fuel long ago.  What's left of it is almost certainly a black hole.  But when that occurred is impossible to know, as the light released when it went supernova still hasn't gotten here.

But still, this is an incredible window on deep time.  I have to wonder what other amazing images we'll get to see soon when the new James Webb Space Telescope, which has better resolution than Hubble, starts sending us data this summer.  I think we've only begun to explore what is out there in the far reaches of the universe, and the far distant past.

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The ghoul's head and the three-body problem

Ever heard of Algol?

Known to astronomers as Beta Persei, it's the second-brightest star in the constellation of Perseus.  It was singled out as strange a long time ago.  Even in a small telescope it looks like a single star, but in 1881 it became the first identified eclipsing binary, a pair of stars orbiting around a common center of gravity with the orbital plane lined up so that from our perspective, one passes in front of the other.  Because one of the stars is dimmer than the other, when the dimmer one crosses in front of the brighter one, the brightness of the pair appears to diminish -- the transit takes ten hours and happens every 2.86 days, so it's regular as clockwork.

The first certain mention of Algol's variability was by Italian astronomer Geminiano Montanari in 1667, but way before that the star had a reputation for being uncanny.  The name Algol comes from the Arabic رأس الغول (raʾs al-ghūl) -- "the head of the ghoul."  The Greeks, who named the constellation in which it resides Perseus, thought that Algol was the Gorgon's head that the hero was carrying.  The ancient Hebrews called it Rōsh ha Sāṭān (Satan's head).  These are similar enough that they probably come from a common source, but the Chinese as well thought there was something evil about it; they called Algol and the stars surrounding it Dà Líng -- the Mausoleum.

So even if there's no certain evidence that the ancients knew about Algol's odd variability, it seems pretty likely.

What no one realized until recently is that Algol is weirder even than that.  To see just how strange it is, first a brief physics lesson.

Some of the great names of physics and astronomy in the sixteenth and seventeenth centuries -- Galileo Galilei, Tycho Brahe, Johannes Kepler, and Isaac Newton, especially -- used highly accurate data on planetary positions to conclude that the planets in the Solar System go around the Sun in elliptical orbits, all powered by the Universal Law of Gravitation.  The mathematical model they came up with worked to a high degree of accuracy, allowing earthbound astronomers to predict where the planets were in the sky, and also such phenomena as eclipses.

Lucky for them, though, that the Sun is so massive.  Because the Sun is huge -- it has a thousand times more mass than the largest planet, Jupiter -- its gravitational pull is big enough that it swamps the pull the planets exert on each other.  For most purposes, you can treat each orbit as independent two-body problems; you can (for example) look at the masses, velocities, and distances between the Sun and Saturn and ignore everything else for the time being.  (Interestingly, it's the slight deviation of the orbit of Uranus from the predictions of its position using the two-body solution that led astronomers to deduce that there must be another massive planet out there pulling on it -- and in 1846 Neptune was observed for the first time, right where the deviations suggested it would be.)

I said it was "lucky" that the mass imbalance is so large, but I haven't told you how lucky.  It turns out that all you have to do is add one more object of close to the same size, and you now have the three-body problem -- a big problem, because physicists have been unable to find a general solution to the equations it generates.  You can pick the parameters (mass, separation distance, initial velocity, and so on) and have a computer model what the orbits would look like, but there's no overarching set of mathematical equations that physicists can use on any other system with different parameters.  The unifying model just doesn't exist, or at least hasn't been discovered yet.

Worse still, most individual three-body systems generate chaotic orbits.  Here's a rather mesmerizing gif showing one of them:

[Image is licensed under the Creative Commons Dnttllthmmnm, Three-body Problem Animation with COM, CC BY-SA 4.0]

The reason this comes up  is a paper in The Astrophysical Journal showing that Algol isn't a simple double star system, with two stars orbiting their common center of gravity like Newton said.  In the 1950s astronomers figured out that the known binary system (Algol A and Algol B) is in an orbit with a third star (Algol C), with the whole trio orbiting their center of gravity once every 1.86 years, and presumably tracing out some kind of bizarre Spirograph pattern like the one in the gif.

But the recent paper showed that it's not even that simple.  Algol isn't a weird, chaotic three-star system.

The "star" we call Algol is apparently made up of at least seven stars all moving in a complex dance around their collective center of gravity.

Algol is in our stellar neighborhood -- only ninety light years away -- so why haven't they been observed until now?

"The paradox is that Algol A is 'too bright,' " said astrophysicist Lauri Jetsu, author of the paper, in an interview with Science Daily.  "It can hide these new companion candidate stars even from our most powerful modern space telescopes, just like our Sun can hide all other stars during daytime...  Even the cutting-edge equipment onboard the Gaia satellite could not detect these new companion candidates.  Future interferometric observations may be used to directly confirm the existence of at least some of Algol's companions."

I find it fascinating that even in a part of physics that is usually considered pretty well sussed-out -- classical mechanics, the study of objects in motion -- there are unsolved problems that the experts consider very close to intractable.  Further reinforcing the notion that the universe doesn't seem to feel obliged to choose how it acts based upon whether humans find it comprehensible.  It does what it does, leaving us to try to explain how on earth (or off it) that kind of thing could happen -- in this case, seven massive objects all whirling around each other in apparently stable orbits.

It's a little like the famous (if apocryphal) story about bumblebees -- that physicists have analyzed their mass, wing size, wing beat frequency, and so on, and have come to the conclusion that bumblebees can't fly.  The bumblebees, not knowing this, go ahead and fly anyway.  Here, the seven members of the Algol system are apparently unaware that the steps of their cosmic dance is beyond what our current physics can explain, but it doesn't stop them from dancing.

Think of that the next time you look at the night sky, and see the bright blue pinpoint of the ghoul's head twinkling against the blackness.

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My master's degree is in historical linguistics, with a focus on Scandinavia and Great Britain (and the interactions between them) -- so it was with great interest that I read Cat Jarman's book River Kings: A New History of Vikings from Scandinavia to the Silk Road.

Jarman, who is an archaeologist working for the University of Bristol and the Scandinavian Museum of Cultural History of the University of Oslo, is one of the world's experts on the Viking Age.  She does a great job of de-mythologizing these wide-traveling raiders, explorers, and merchants, taking them out of the caricature depictions of guys with blond braids and horned helmets into the reality of a complex, dynamic culture that impacted lands and people from Labrador to China.

River Kings is a brilliantly-written analysis of an often-misunderstood group -- beginning with the fact that "Viking" isn't an ethnic designation, but an occupation -- and tracing artifacts they left behind traveling between their homeland in Sweden, Norway, and Denmark to Iceland, the Hebrides, Normandy, the Silk Road, and Russia.  (In fact, the Rus -- the people who founded, and gave their name to, Russia -- were Scandinavian explorers who settled in what is now the Ukraine and western Russia, intermarrying with the Slavic population there and eventually forming a unique melded culture.)

If you are interested in the Vikings or in European history in general, you should put Jarman's book in your to-read list.  It goes a long way toward replacing the legendary status of these fierce, sea-going people with a historically-accurate reality that is just as fascinating.

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