
Researchers have identified 100 mysteriously disappeared stars in the night sky - nabla9
https://www.sciencealert.com/a-look-through-past-star-catalogues-finds-scores-of-stars-that-have-mysteriously-vanished
======
shadowgovt
My experience with big data analysis immediately leads me to suspect that in a
dataset of tens of millions of elements, 100 elements having anomalous
behavior can actually be operator error, hardware error, noise, anomalous
near-Earth object miscatalogued as a star, &c. The article touches on this
possibility: "Another explanation – although very unlikely – is they're all
just scratches after all, and never existed to begin with." It's unlikely, but
unlikely phenomena become phenomena one expects to see if one "rolls the dice"
10 million times.

But it is still an interesting story and a topic worth exploring, even if
subsequent research concludes the team has found 100 smudges on glass.

~~~
michelpp
These are comparisons of deep, long exposure time survey images. They aren't
imaging one star at an instant time, but entire fields of them over many
minutes to hours, so:

> operator error

would effect the entire image. If it were damage to the film/sensor, scratches
etc, it wouldn't look like a star point source with a star like point spread
function.

> hardware error, noise

Digital sensors do add noise to an image, but it doesn't occur as bright point
sources concentrated in a small area. noise can be removed through statistical
analysis, dark frame subtraction, lucky imaging, etc. Dust on the lenses or
mirrors aren't in the focal plane and don't resolve to points. Dust on film or
sensors would block light, not produce it. Many exposures all over the sky
quickly characterize the on sensor defects and other instrument specific
information that can be removed from the data.

> anomalous near-earth objects

these are long exposures, if they are anomalous objects, they would have to
have very slow apparent motion against the stellar background. satellites and
planes would leave trails. balloons would drift with the wind. what would stay
basically static through the entire long-exposure against the celestial
sphere?

I appreciate your skepticism, I'm just taking the other side of the argument.
Thoughts?

~~~
anewguy9000
im with you. this is astrophysics: there are other lines of evidence to
consider: like the missing stars sharing certain properties (color, velocity),
suggesting an astrophysical explanation (remember it's not strange for stars
to go away. whats new here is how)

------
craigr1972
[https://en.wikipedia.org/wiki/The_Nine_Billion_Names_of_God](https://en.wikipedia.org/wiki/The_Nine_Billion_Names_of_God)

..they notice that "overhead, without any fuss, the stars were going out."

~~~
bloopernova
I very much like the 2 part epic space opera "Pandora's Star" and "Judas
Unchained" by Peter F Hamilton.

In it, an Astronomer spots a star that disappears. This star is 1,500 light
years away. He travels to another star system (Humanity is a multi-system
species) and observes the star again, at just the right moment to see the
light from its disappearance. It disappears within a couple of seconds, as
does a nearby star. But its infrared output is undimmed.

This kicks off an epic, and I really do mean epic, space opera. Peter F
Hamilton is really great at such stories, and I love this pair of books so
much that I've read them about a dozen times each.

Highly recommended!

~~~
iamrecursion
I’ll echo this recommendation. Peter F. Hamilton is firmly my favourite sci-fi
author, and that’s a hard spot to take.

The Commonwealth Saga (mentioned by the parent) is followed by The Void
Trilogy and then The Chronicle of the Fallers, all set in the same
Commonwealth universe. It’s some of the most evocative writing I’ve ever heard
the pleasure to read, and the stories told are massive in scale but without
seeming lacking as a result.

My e-reader says that my most recent read-through was my 9th, so add that to a
number done with physical books and it should give some idea of how good I
consider these books!

~~~
wjnc
I read quite a lot of books thanks to suggestions on HN, so my thanks to all
giving suggestions!

------
sonofgod
From the paper: [https://sci-hub.se/10.3847/1538-3881/ab570f](https://sci-
hub.se/10.3847/1538-3881/ab570f)

"We show that these objects are redder and have larger proper motions than
typical USNO objects." \-- Interesting, not sure what that'd imply.

"A particular focus is given to USNO objects that have several detections
before vanishing" \-- implies that these at least some of these objects are
not just detector glitches or scratches or similar, although "Visual checks
confirm that indeed the most interesting cases, about 100, are mostly one-time
detections in the red band."

"In a separate paper by K. Pelckmans et al. (2019, in preparation). we propose
a new tool for handling a large number of images using methods of machine
learning." (since people were talking about ML in astronomy)

~~~
mirimir
> Visual checks confirm that indeed the most interesting cases, about 100, are
> mostly one-time detections in the red band.

So that could be fusion torch flashes. Or maybe weapons.

I wonder if they have spectra for any of these suspects.

------
lsh123
Universe v2432134542235788654 Release Notes

=============================================

* Removed ~100 stars to fix bug #9533465222. If your star was affected, please reach out to customer support.

~~~
misterman0
Customer support, when we applied the latest upstream patch we notice
E=MC^2+0.001. Please advice.

~~~
primordialsoup
Please upgrade to premium service to get an answer.

------
fsiefken
I was reminded of a great start of a sci-fi novel:

“The star vanished from the centre of the telescope’s image in less time than
a single human heartbeat. There was no mistake, Dudley Bose was looking right
at it when it happened. He blinked in surprise, drawing back from the
eyepiece. “That’s not right,” he muttered.

He shivered slightly in reaction to the cold air around him, slapping gloved
hands against his arms. His wife, Wendy, had insisted he wrap up well against
the night, and he’d dutifully left the house in a thick woollen coat and
sturdy hiking trousers. But as always when the sun fell below Gralmond’s
horizon, any warmth contained in the planet’s thinner-than-average atmosphere
evaporated away almost immediately. With the telescope housing open to the
elements at two o’clock in the morning, the temperature had dropped enough to
turn his every breath into a streamer of grey mist.

Dudley shook the fatigue from his head, and leaned back in to the eyepiece.
The star field pattern was the same, there had been no slippage in the
telescope’s alignment, but Dyson Alpha was still missing. “It couldn’t be that
fast,” he said.

He’d been observing the Dyson Pair for fourteen months now, searching for the
first clues of the envelopment which would so dramatically change the emission
spectrum. So far there had been no change to the tiny yellow speck of light
one thousand two hundred and forty light-years away from Gralmond which was
Dyson Alpha.

He’d known there would be a change; it was the astronomy department at Oxford
University back on Earth that had first noticed the anomaly during a routine
sky scan back in 2170, two hundred and ten years ago. Since the previous scan
twenty years earlier, two stars, a K-type and an M-type three light-years
apart, had changed their emission spectrum completely to non-visible infra
red. For a few brief months the discovery had caused some excited debate among
the remnants of the astronomy fraternity about how they could decay into red
giants so quickly, and the extraordinary coincidence of two stellar neighbours
doing it simultaneously. Then a newly settled planet fifty light-years farther
out from Earth reported that the pair were still visible in their original
spectrum. Working back across the distance, checking the spectrum at various
distances from Earth allowed astronomers to work out that the change to both
stars had actually taken place over a period of approximately seven or eight
years and was simultaneous. Given that speed, the nature of the change ceased
to become a question of astronomy; stars of that nature took a great deal
longer to transform themselves into red giants."

\-- Peter F. Hamilton. Pandora's Star

~~~
bsder
Sorry, Peter F. Hamilton's _ideas_ are awesome but his writing--not so much.
He desperately needs an editor to chop out 1/3 to 2/3 of his words.

I'm reminded of an old Bugs Bunny cartoon: Detective: "Okaaaay, start at the
beginning." Bugs: "In the beginning, the Earth was without form and void ..."
Detective: "You can skip ahead a bit, thanks ..."

~~~
jacquesm
Maybe he gets paid by the word?

~~~
DrScump
That's why I hated Dickens' novels.

~~~
bsder
Ayup. "Tale of Two Cities" is a wonderful book with a sub-par book sandwiched
in the middle.

------
ncmncm
Probably the denizens of the next star over noticed that the star in question
had inhabited planets, and turned it off against the possibility they might,
otherwise, someday become a threat.

This is a candidate for the Great Filter: interstellar civilizations that come
into contact destroy one another.

~~~
wostusername
Since everything in physics tells us that FTL travel is impossible (as far as
I am aware), then when a civilization detects signs from another civilization
in another solar system it knows that 1) that civilization was advanced enough
to produce signals into space light years ago, and 2) by the time it reaches
it at sublight speeds (hundreds, possibly thousands of years) it will be more
advanced still. That means your extermination mission might be facing a
technologically superior enemy with home field advantage.

~~~
zaphirplane
This may be where intuition and cosmic scale don’t align. The Milky Way is
very old and is ~100k light years in diameter.

Say you are a few million year old civilization and you detect radio from a
civilization 100k light years away takes 500k years for you fleeting arrive.
You are still millions of years ahead in technology. If you are a stagnant
civilization you probably stay home cause the other side would overtake you,
but then again that motivation to get to them as early as possible. In any
event presumably as your fleet get closer you would have a better idea of the
technology difference and can just do a U turn

~~~
ncmncm
Civilizations that come into contact will tend to be those that are closer
together, particularly if they make any effort to be inconspicuous.

The longer they go without contact, the wider their reach, and the greater
their odds of contact.

We might suppose that the technology necessary to obliterate another
civilization is arrived at early, and is hard to counter despite long
subsequent development. Alternatively, civilizations that succeed in
suppressing weaker ones eventually meet their match.

------
codezero
This reminds me vaguely of the community science project I contributed to a
few years ago trying to investigate why epsilon Aurigae [0] goes dim every ~27
years. It turns out to be a likely dust disk of an orbiting body that dims the
main star and happens to be directly along the line of sight with Earth.

I imagine there are a lot of possible ways a line of site occlusion could
cause a dim star to appear as not existing at all, and as another commenter
mentions, maybe the original measurement was some sort of amplification in the
first place.

Space is damn cool.

[0]
[https://en.wikipedia.org/wiki/Epsilon_Aurigae](https://en.wikipedia.org/wiki/Epsilon_Aurigae)

------
alejohausner
Could it be gravitational microlensing? Maybe the apparent magnitude of the
missing stars was amplified by an intervening massive object just as the older
pictures were taken.

~~~
BurningFrog
That seems likely to this amateur.

Lensing could also move the (perceived) location of a star.

------
pmoriarty
_" there seem to me too many anomalies to explain all the vanished stars as
known natural phenomena. In their current paper, the authors themselves
discuss the possibility that they're seeing unknown phenomena, or that the
vanished "stars" could be relics of technologically advanced civilizations,
particularly the theoretical mega-engineering projects known as Dyson
spheres."_

What about the possibility that the inclusion of those stars in those 1950's
star catalogs was a result of human error, instrument error, or scientific
fraud?

~~~
RedOrGreen
This is a comparison of images, not just catalogs of sources in images. If you
look at the image in the linked article, you can easily spot one of the stars
that has "gone missing".

Looking at the brightness of the source that went missing, it is hard to
suggest instrumental error - much fainter stars remain detectable in both
epochs.

And fraud, really? Who would bother to fake stars in catalogs and plates in
the 1950s, and why?

~~~
GuiA
So they could identify who plagiarized their catalogs?

[https://en.wikipedia.org/wiki/Fictitious_entry](https://en.wikipedia.org/wiki/Fictitious_entry)

~~~
ben_w
Well you could, but why would you want to? Other than video games which didn’t
exist in 1950, I can’t think of any reason someone would use a star catalogue
in a for-profit scenario.

------
zqfm
Trap stars?
[https://en.wikipedia.org/wiki/Fictitious_entry](https://en.wikipedia.org/wiki/Fictitious_entry)

~~~
avian
Ah, a star catalogue equivalent of non-existent streets in a map that are only
drawn there to prove copyright infringers. Somehow I was expecting to read
about a stellar equivalent of a D&D mimic.

------
jagger27
I bet some of them are moving a little faster than we expected them to and are
just not where we last saw them. Creepy nonetheless.

~~~
ceejayoz
I don't think that's likely. It takes the closest star 5,000 years to move the
distance our moon covers in the night's sky.

Video of ten years worth here:
[https://www.facebook.com/watch/?v=10160104518220167](https://www.facebook.com/watch/?v=10160104518220167)

~~~
ben_w
I was thinking that, but if these objects are much closer than expected, small
physical motion could be a large angular motion. I don’t know if that would be
_enough_ to explain them away.

------
unimpressive
Obligatory Sci-Fi premise:

[https://www.greaterwrong.com/posts/5wMcKNAwB6X4mp9og/that-
al...](https://www.greaterwrong.com/posts/5wMcKNAwB6X4mp9og/that-alien-
message)

~~~
Treblemaker
Thank you! I've been searching all afternoon for this one.

------
8bitsrule
In case there's any interest, this Archiv page includes a PDF.
[https://arxiv.org/abs/1911.05068](https://arxiv.org/abs/1911.05068)

"We visually examine the images for a subset of about 24,000 candidates,
superseding the 2016 study with a sample ten times larger. We find about ∼100
point sources visible in only one epoch in the red band of the USNO which may
be of interest in searches for strong M dwarf flares, high-redshift supernovae
or other catagories of unidentified red transients.

Comments: SETI meets time domain astronomy."

------
acqq
The paper:

"The Vanishing and Appearing Sources during a Century of Observations Project.
I. USNO Objects Missing in Modern Sky Surveys and Follow-up Observations of a
"Missing Star"" Beatriz Villarroel et al 2019 December 12, The Astronomical
Journal, Volume 159, Number 1

[https://doi.org/10.3847/1538-3881/ab570f](https://doi.org/10.3847/1538-3881/ab570f)

------
garmaine
Something in the foreground that was originally misclassified as a star?

~~~
teilo
This is my thought. I suspect these are asteroids. The tell is whether the
stars show up on plates, say, a year later. If so, then they're not asteroids.

However, that seems to have been ruled out in the Astronomical Journal
article:

"Given the exposure time of 45 minutes of the POSS-I E red image, if our
object were an asteroid that quickly moved out of the field, it would have
left a stripe (and not be point-like)." (Page 5)

"The exposure time for the red image is about 50 minutes. If the object were
an asteroid and was quickly moving through the field of the red image in a few
minutes, then it would be elongated on the plate. However, this object is
point-like. In addition, the candidate is anomalously red and not seen in the
blue band, which further decreases the likelihood that it is an asteroid."
(Page 13)

~~~
garmaine
That doesn’t rule out foreground objects at all. Kuiper belt objects are
distinctly red, as we learned from New Horizons, and so far away that they
wouldn’t noticeably move over 45min.

~~~
teilo
The question is whether such Kuiper objects would show up on the old POSS
plates. I don't know enough about that, so I yield to those who do. It
certainly seems a more plausible explanation.

------
ajuc
Could it be that a group of stars was passing by between us and the stars that
remained when the first picture was taken?

------
Izkata
Wellp, my crazy sci-fi thought:

 _There are patches in the sky._

( [https://en.m.wikipedia.org/wiki/Lexx](https://en.m.wikipedia.org/wiki/Lexx)
)

------
mileycyrusXOXO
While an interesting article, I wish people didn't feel the need to try to
make things out to be more 'exciting' than they likely are. I think it takes
away a lot from the real reasons to be excited. This seems to be common in
astronomy journalism.

"Hmm, we've observed something weird. What could be some reasonable
explanations? We'll dedicate 3 to 4 sentences on those then spend the rest of
the article talking about Dyson Spheres and extraterrestrial star ships."

~~~
dang
Ok, we've changed the URL from [https://www.airspacemag.com/daily-
planet/stellar-mystery-how...](https://www.airspacemag.com/daily-
planet/stellar-mystery-how-could-100-stars-just-vanish-180973821/) to a
different popular article that seems to dwell on topic somewhat longer before
the aliens show up.

------
ImaCake
For those a little sceptical of traditional dyson spheres, like the linked
article, there are many more ways to envision such a sphere. My personal
favourite is a kind of computonium dust layered loosely around the star, like
that found in Charles Stross' Accelerando.

~~~
aardvark179
True, but Dyson spheres should be easily visible in the infrared, and I know
searching for them is set as an undergrad project by at least one IR astronomy
professor. So, I’d expect them to be spotted by now if they are widespread.

~~~
ceejayoz
It seems silly for us to make a bunch of rigid conclusions about an
unimaginably high technology solar-system scale megastructure.

~~~
ben_w
We could make one with known tech, it would only take a few thousand years
thanks to exponential population growth and humans being universal
constructors.

We’d expect to see Dyson swarms’ heat signatures because of the laws of
thermodynamics. If super-advanced aliens can avoid or circumvent
thermodynamics, all bets are off.

~~~
ceejayoz
The laws of thermodynamics don't forbid radiating heat in a directed manner,
right?

~~~
ben_w
I think you’re only able to do that if you’re not in thermal equilibrium.

I’m not a trained physicist, so I’m not 100% certain about this, however the
phrase “there is no stealth in space” seems to come up a lot in the stuff I
read, and that specifically excludes directing heat away in specific
directions.

~~~
ceejayoz
I'd think you could do something like have a deep, V-shaped hole with
radiators at the bottom, and really good insulation / conductors throughout
the sphere to funnel heat into that radiator. Anything radiating in the wrong
direction would just get picked back up and re-directed through the system
again.

Point that V into deep intergalactic space and buy yourself a few hundred
million years.

------
choxi
Has anyone used machine learning to help identify and track stars in the data
set they mention? I'd love to contribute to space exploration as a software
engineer, and building systems to analyze the data seems like one promising
approach.

~~~
karthikb
Take a look here:

[https://arxiv.org/search/?query=astronomy+machine+learning&s...](https://arxiv.org/search/?query=astronomy+machine+learning&searchtype=all&source=header)

 _Plenty_ of ML work being applied to astronomy. Much of the code is open
source too so you can dive right in and contribute.

Here's a recent survey you might start with:
[https://arxiv.org/pdf/1912.02934.pdf](https://arxiv.org/pdf/1912.02934.pdf)

------
mindcrime
Davros and the Reality Bomb[1]?

[1]:
[https://en.wikipedia.org/wiki/Journey%27s_End_(Doctor_Who)](https://en.wikipedia.org/wiki/Journey%27s_End_\(Doctor_Who\))

------
trhway
Fermi style estimate: 600M stars with live spans from several billions to
several millions years, say average - 600 million years, thus 1 star per year
got to go. 50 years - 50 stars.

------
buzzert
Not a single mention of Katamari Damacy in this whole thread? Players of that
game all know it was because of the King of All Cosmos and his clumsiness!

------
sitkack
What do the stars look like in 3d space? Do they form some sort of wavefront?

------
carapace
Are the stars vanishing in the _sky_ or just in the _data?_

Are stars also appearing?

~~~
teilo
They are photographic plates, then vs. now. This cannot be dismissed as simple
user error. Especially in 1950 where we did not have to contend with this
massive population of artificial satellites. Other solutions must be sought.

What is not clear to me is whether one can find these missing stars on other
plates taken at a later time. If so, then this lends credence to some sort of
stellar phenomenon. The paper rules out asteroids due to the long exposure
times of the images, which would have turned any objects moving in our solar
system into a smear rather than a point source.

~~~
pbhjpbhj
What chemistries are we looking at, near-Earth phenomena might be responsible
for the appearance of one-time "stars" on a photographic plate. I'm thinking
cosmic-rays but I'm sure there are a tonne of potential sources.

Perhaps also different wavelength star sources too? Or are they doing the
observations across the whole spectrum (that's probably common nowadays?).

------
kresten
It’s not aliens.

~~~
koheripbal
It's always not aliens until the day it is.

------
swayvil
Somebody is building Dyson Spheres, obviously.

------
alecco
Flip burn?

------
Razengan
The simulation is shutting down.

~~~
troymc
Or maybe some memory got corrupted by a passing cosmic ray (out in the
realverse).

------
ur-whale
Dyson spheres completed baby !

------
m3kw9
Something out there low on power and needs recharging

------
jhoechtl
Jim Carrey almost got hit by a spot. Someone to change the light bulbs
quickly!

------
bitwize
No... it was indeed not a dream. We really did it. The King of All Cosmos
really has done it. A sky full of stars... We broke it. Yes, We were naughty.
Completely naughty. So, so very sorry. But just between you and Us, it felt
quite good ️

------
ThinkBeat
Dust on the optics or on the film during development.

~~~
anigbrowl
Please don't post comments without reading the article first. It just wastes
everyone's time.

 _That short list was visually inspected, excluding around 18,000 images that
were messed up by flaws or artefacts. Lastly, the team removed images where
the missing star was towards the edge of the field, just to reduce risk of any
false positives.

One final sweep using yet another method for comparisons removed other
possible flaws in data collection, or unclear results. That left 100 dark
shadows where a star once shone._

------
mrfusion
I’m guessing this is related to rising co2 and climate change. Dampens out
what we can see.

------
tlbsofware
What if these aren’t stars that are disappearing but instead the appearances
and disappearances of wormholes that are either allowing us to see to another
place in space where that star is or perhaps a wormhole blocking where that
star previously was for us and we are now looking into another section of
space where a star is not?

~~~
rossdavidh
While fun to think about, I think it is hard to go anywhere, scientifically,
from such a proposition. How would you disprove it?

~~~
tlbsofware
Hmm haven’t thought of how to disprove it but there is a theory about
measuring the red shift[0] around the “object” in this example the wormhole

[0] [https://www.livescience.com/64033-shape-of-a-
wormhole.html](https://www.livescience.com/64033-shape-of-a-wormhole.html)

------
ArtWomb
"Once you eliminate the impossible, whatever remains, however improbable, must
be the Truth" -Sherlock Holmes

It seems like now might be the perfect time, for the price of a single space
telescope, to build an exa-scale computer capable of simulating _every_
extreme astrophysical event.

Technosignature "clues", and all probable causes could be instantly
classified. It's now also possible to add gravity waves and neutrinos to the
simulation ;)

~~~
krapp
>"Once you eliminate the impossible, whatever remains, however improbable,
must be the Truth" -Sherlock Holmes

This axiom works in the fictional universe of Sherlock Holmes, where it's
guaranteed that the protagonist will know all of the variables with perfect
unbiased clarity and can, therefore, eliminate all unnecessary possibilities
and solve the case.

But in the real universe, one often cannot "eliminate the impossible," because
one cannot always know everything that is possible, or where ones assumptions
are wrong.

>It seems like now might be the perfect time, for the price of a single space
telescope, to build an exa-scale computer capable of simulating every extreme
astrophysical event.

This is a good example of what I mean. We don't know what the set of all
extreme astrophysical events contains, or what their nature is (ex: dark
matter and dark energy) and we're constantly discovering new events and
phenomena. If we _could_ perfectly simulate the universe in this manner, we
wouldn't _need_ to.

And this is why, despite many fields of science already spending far more than
'the price of a single space telescope' to simulate everything from the Big
Bang to biology and neurons to particle collisions, "instant classification of
everything" isn't possible.

That's just not a thing that computers can do outside of science fiction.

~~~
ArtWomb
But "possible / impossible" seems in itself to be a really useful classifier!

Perhaps not worthy of exa-scale computing resource allocation. When it could
be put to better use in say, nuclear fusion instability prediction. And with
the qualifier "possible" conditioned on "known astrophysics by humans in the
early 21st Century". But still an interesting tool for likelihood candidate
detection.

And it still seems constrained to me at least (not a professional astronomer)
by the scale of astrophysical phenomena which would be detectable here across
the vast expanse of space. It could be an infinite set, certainly.

But so far we have cataloged only a handful of significant sources of, in the
case of gravitational wave interferometry, bursts: black holes, quasars,
pulsars, neutron stars...

[https://www.ligo.caltech.edu/page/gw-
sources](https://www.ligo.caltech.edu/page/gw-sources)

