On this channel a common theme is coverage of astronomical objects that should not behave
as they do.
These include the usual suspects such as Przybylski’s star and the transuranic elements apparently
in it, and the mysteriously dipping star KIC 8462852.
But there are a number of such objects that I’ve never covered or only briefly touched
on, and a few that are new discoveries, so here are 10 astronomical objects that are
not behaving as they should.
Number 10.
The Galaxy with not Enough Dark Matter
One of the great mysteries of science right now is what the nature of dark matter could
be.
Our understanding of dark matter, murky though it is, comes largely from the behaviour of
galaxies.
Without the presence of dark matter, they would fly apart.
Therefore there must be something that interacts with normal matter gravitationally, but since
we can’t see it and haven’t detected it, then it must not interact in any other way.
The nature of dark matter is a complete unknown, but the general view of late is that it’s
likely to be in the form of an unknown particle known as a WIMP, or weakly interacting massive
particle.
There is also an opposing point of view that says that rather than invoking invisible matter,
shouldn’t we first try to determine if there is something wrong with our models of how
gravity behaves at long distances.
And then came the galaxy NGC 1052-DF2.
This galaxy is ultra diffuse and on its face it appears to have very kittke dark matter.
As is usual, the galaxy was reexamined and a number of papers came out questioning the
distance to the galaxy and reconciling that it actually did have the normal amount of
dark matter.
Then another galaxy like it was found, complicating the matter and painting a picture of these
types of galaxies that seem to not contain dark matter as not particularly rare in the
universe.
So the matter remains unresolved.
However if it is determined that these types of galaxies are in fact devoid of dark matter
then it casts a shadow on both points of view.
Whether the discrepancy in our understanding of gravity or the existence of weakly interacting
particles, they both should be universal and seen in all galaxies.
If that’s not the case, then it’s back to the drawing board as to explaining just
what dark matter is.
Number 9.
The Intermittent White Dwarf
We often refer to white dwarfs as dead stars.
Glowing cinders of stars radiating their remaining heat until eventually they are predicted to
go black.
But there’s more to that story.
Sometimes white dwarves in binary systems can accrete material from their companion
star, not entirely unlike the accretion disk of a black hole.
This causes white dwarfs to brighten as material is drawn in from the other star and act as
sort of zombie stars.
A few days ago however a team at Durham University in the UK announced that they found a white
dwarf that suddenly switched off.
The system in question is TW Pictoris, and consists of a white dwarf feeding off of another
star.
Normally this situation is called a cataclysmic variable, where the accreting material can
cause the white dwarf to brighten.
This used to be called a nova, but it’s complicated in that in certain cases it can
actually cause a class of supernova that destroys the white dwarf involved.
Exploding zombie stars.
But with TW Pictoris, it’s rises and falls in brightness are on very short time scales,
not seen with any other white dwarf so far.
It can rise and fall dramatically in brightness over the course of just 30 minutes.
The working hypothesis of why this is has to do with the white dwarf’s magnetic field
interrupting the flow of material from the accretion disk that happens on very short
timescales.
But more of these types of situations should be seen, and probably will be, but so far,
nothing yet.
Number 8.
The Green Star
Humans have looked at the stars since the beginning.
The very first creature that could be called human almost certainly looked up at the night
sky and wondered what the points of light were.
It may have even formed, or inherited, a mythology regarding the stars and planets overhead,
something that is common to just about every group of humans that have ever existed.
Indeed, what might be the oldest myth preserved in humanity deals with the pleiades, and concerns
multiple identical stories about a seventh star in that system, the seven sisters being
chased by variations on the constellation Orion, when you actually only see six with
normal human vision.
This story ranges from ancient Greece to the middle east to very distant and then isolated
Australian aboriginal cultures separated from parts of humanity having the same story for
as much as 50,000 years.
This implies a story that has been passed down in many traditions since they last had
contact.
As a result, this story could be as much as a hundred thousand years old.
And that seventh star which is no longer visible to the normal naked eye, exists.
It’s just not visible to modern humans.
This interest in the sky also gives us a long record of human observations of the heavens
from multiple different sources dotted across the earth allowing us to look for things like
past supernovas in the historic record.
But this also has led to discrepancies, where ancient accounts of the night sky don’t
actually match what we see today.
One example of this is the star Beta Librae.
There are actually two discrepancies with this star in the historical records.
The first concerns its brightness.
Eratosthenes noted that this star was brighter than Antares, yet three centuries later Ptolemy
said it was as bright as Antares.
If these observations are correct, and remember they were visual made by ancient Greeks, then
something changed.
It’s uncertain what, but it could be that Antares has brightened, or Beta Librae is
a very long period variable star.
The second discrepancy is in the star's color.
An inordinate amount of historical observers have called this star green.
It’s not, it’s a blue-white star, and a green appearance is due to the human eye
when looking at dim objects and actual green colored stars do not exist in nature, though
stars do emit green light.
But this star does not appear greenish today to any observer.
So it remains a mystery as to why people in the past saw it as greenish.
Number 7.
The Tired Pulsar
Pulsars are usually very regular things, operating like clockwork so precisely that you could
almost use them to set a clock to a precision rivaling an atomic clock.
But for reasons largely not understood, they can simply stop pulsing for a time.
This is known as nulling, and the pulsars that do it tend to only stop pulsing on a
time scale of a few pulse periods to a few days.
This is thought to be due to one of two things.
Either there is some intrinsic issue going on with the star itself, such as something
related to a starquake perhaps.
This is known to probably cause what’s known as glitching in pulsars and results when the
pulsar’s crust cracks and moves disrupting everything including its magnetic field.
Or it could be due to something going on with the pulsar’s magnetosphere itself.
Either way though, those effects should be relatively transient.
But there are two pulsars that don’t quite fit here, and it’s very unclear why.
The first is a pulsar known as PSR B1931+24, where you see the pulsar for about a week.
Then it stops for a month.
And then turns back on for a week in a regular cycle.
It could be that under certain conditions a pulsar can change the direction of its beam
and we no longer see it, and then return in some kind of cycle that’s going on in its
magnetosphere.
But this appears to be a rare type of pulsar working on a mechanism we don’t understand.
But, as usual on this channel, there’s a worse one.
The pulsar PSR J1841-0500 is a very distant pulsar at over 22 thousand light-years away.
This pulsar was discovered in 2008 and seemed to be normal, pulsing regularly every .9 seconds.
But in 2009, it stopped completely.
After a few days, it still wasn’t there.
After a few months, it was still not there.
This pulsar was silent for 580 days before it abruptly started pulsing again in August
of 2011.
So far, no other pulsar like this has been found, and what exactly happened there is
unknown.
Number 6.
The Star Within a Star
Within theoretical astrophysics there is an object known as a Thorne-Zytkow object.
I’ve covered this concept on this channel before, so I won’t go into detail, but essentially
it’s a situation where a neutron star and a red giant merge leading to a stable situation
where the neutron star exists at the core of the red giant, making for two stars in
one.
But that idea was only ever hypothetical.
But it was testable, and made chemical predictions.
These predictions included abnormally high levels of certain elements coupled with high
luminosity.
This in principle should be detectable in the star’s spectrum, so searches have been
made.
The first candidate for such an object was HV 2112, which showed over abundances of lithium,
calcium, molybdenum, rubidium and others which would have been consistent with one of these
objects.
This was called into question however by another team that argued that only lithium seemed
elevated.
But another candidate has shown up known as HV 11417 that seems to have too much rubidium
and a high luminosity making it a somewhat strong candidate for a Thorne-Zytkow star
within a star.
Number 5.
The Oldest Black Hole in the Universe
The quasar ULAS J1342+0928 is the second most distant quasar known.
Within this highly active galaxy, astronomers have found a supermassive blackhole weighing
about 800 million times the mass of the sun.
While there are supermassive black holes far more massive than that, the size of this black
hole presents a mystery.
The reason is that this particular black hole is so distant, that it’s oldest black hole
that we know of dating to have formed only about 690 million years after the big bang.
This is interesting, because when the light left this quasar, the universe was in a bit
of a different state than it is right now.
This is known as the epoch of reionization, and quasars may be key to understanding how
this reionization occurred, making quasars that distant important objects of study.
But by being such an early object, this black hole intuitively shouldn't be as massive as
it is.
Yet it exists, presenting a challenge to current models of black hole formation.
Number 4.
Our Solar System: Why haven’t we found another?
One thing we’ve noticed recently as we’ve studied exoplanets is that so far, no other
star system we’ve seen looks quite like this one.
For example an entire common class of exoplanet known as super earths is unknown here, the
solar system has no super earth.
The list goes on, this solar system has no hot jupiters, brown dwarfs, and where our
star system really stands out is that it has an inhabited planet with a civilization living
on it.
This may indicate that there’s something we don’t know about planet formation and
that our solar system formed under unusual conditions.
This has an unusual implication in that it could mean that earth’s are rare and only
form under the conditions of a special type of protoplanetary disc.
It would not be unique, merely rare.
The interesting thing about this is that we’re actively studying exoplanet systems and new
ones are identified all the time.
As we characterize our ever growing sample, it should become apparent whether the solar
system truly is a rare configuration, or if it has analogues in the local neighborhood
of stars.
Number 3.
Strange Radio Waves from the Center of the Galaxy
As radio astronomy has progressed in recent years, a number of new unexplained signals
have cropped up.
This is especially the case near the center of the galaxy, where a number of transient
radio signals have been detected forming several new classes of unknown object.
Known as Galactic Center Radio Transients, there are several of these phenomena, but
one in particular is quite recently identified.
Known as ASKAP J173608.2-321635, this new object is thought to be related to GCRT’s,
but isn’t exactly like other known examples.
This radio source initially came in as a polarized signal, meaning that it’s waves oscillate
in only one direction, but over time the whole thing rotated.
Also the signal varied in strength, and finally it intermittently disappears only to come
back.
This signal doesn’t really match other known astrophysical phenomena, but also doesn’t
look artificial.
So this probably represents some new astrophysical phenomenon we haven’t seen yet that is dependent
perhaps on the conditions present in the cramped center of the galaxy.
Number 2.
The Infrared Laser Star
MWC 349 is a double star, made up of a giant star, and a supergiant star orbiting each
other.
Due to some unusual properties associated with this system, it’s possible that there
is a third star in the system.
What’s going on here isn’t entirely clear, but one of the stars seems to have a high
mass loss rate and doesn’t neatly fit into any normal star categories.
There is also a disk of material in the system that doesn’t appear to have originated from
the star, so it may be that this is a very young star system, recently ejected from a
nearby nebula.
But the strangest aspect of this star is that the debris disk seems to be generating infrared
laser and maser light.
It seems that some configuration of the dust and gas is organizing the light.
This is not unheard of, there is one other example of a star emitting laser light, but
it’s doing it in ultraviolet.
How an infrared laser is being generated here is a mystery.
Number 1.
The New Mystery
Recently, a new addition to the list of strangely dipping stars was added.
This is the binary star system TIC 400799224, located about 2300 light years from earth.
This is a discovery by the TESS satellite, which looks for exoplanets through the transit
method and is a successor to the Kepler mission that found KIC 8462852.
Once every 19.8 days, something passes in front of this star blocking starlight.
That’s a very short period, so in each successive pass you’d expect it to appear roughly the
same.
That is not the case, whatever is bloçking the starlight varies wildly in both depth
of dip which ranges from a few percent to 25 percent so far, and over varying periods
of time of up to several days.
There have also been observations that when a dip was expected, nothing happened and no
material seemed to have passed in front of the star.
This rules out a lot of things.
Planets don’t change repeatedly over the course of 19.8 days, but normal dust clouds
don’t either.
So whatever is happening is emitting dust, the dust cloud drastically changes shape,
before being blown out of the system by the star’s solar wind.
To account for this requires a massive amount of dust being created.
Even large asteroids losing dust somehow wouldn’t last long on astronomical scales.
So the best current working hypothesis is that it’s two objects, large asteroids perhaps,
repeatedly smashing into each other and intermittently generating dust.
But that may not cover all aspects of what’s being observed, so for now, it remains an
unknown.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently taking a break from
spooky october scripts, but just wait, they’ve been spooky so far, but now we move to the
terrifying and be sure to check out my books at your favorite online book retailer and
subscribe to my channels for regular, in-depth explorations into the interesting, weird and
unknown aspects of this amazing universe in which we live.