
Tabby's star is dimming at an incredible rate - ChuckMcM
http://www.sciencealert.com/we-just-got-even-weirder-results-about-the-alien-megastructure-star
======
erdevs
Good ol' PV on Kinja (from the linked gizmodo article:
[http://gizmodo.com/the-so-called-alien-megastructure-just-
go...](http://gizmodo.com/the-so-called-alien-megastructure-just-got-even-
more-my-1784883811)) has some interesting thoughts, as usual.

> _The biggest axe against it being an alien megastructure project is the fact
> its an F-type star. F-types only live a couple billion years, depending on
> mass._

> _But the drop in the radiant flux... a sustained drop. That could be
> something far more interesting. If you could do stellar engineering... you
> could draw the material off an F-type star while altering its core. You
> could reduce the mass to a G or K star, greatly increasing its lifespan...
> and gaining trillions upon trillions of tons of raw material with which to
> build an alien megastructure..._

~~~
CamperBob2
I'm sorry, I must've missed something important because I've seen pointers to
this post elsewhere. Who exactly is "PV on Kinja?"

~~~
erdevs
"PV" is a user's name on Kinja, which is the commenting system that gizmodo et
al use.

------
simcop2387
Two reddit discussion that might be able to answer some questions we have
here:

[https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper...](https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper_on_tabbys_star_no_known_or_proposed/)

[https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont...](https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_montetjoshua_simon_paper/)

They also contain links to the resulting paper itself

~~~
fjarlq
Reddit user sigbjoernwilderness's idea is pretty wild... can it be easily
ruled out?

> _Is this the last remaining explanation after Montet /Simon?_

> _The dimming comes from the shadow of a spaceship traveling on an (almost)
> straight line from KIC8462852 to Earth. The slow continuous dimming results
> from the increase of the apparent size of the approaching ship while Earth
> /Kepler is in the penumbra. The irregular dips happen when Kepler
> accidentally passes the antumbra. A rough estimation by simple geometry
> would suggest that the alien spaceship is quite big (> 100 km diameter),
> significantly slower than light velocity (< 0.05 c) and has now almost
> reached its goal (< 2 ly away), arriving at Earth within the next 100 years
> after a journey of several 10,000 years. (cf.
> [http://archimedes.soup.io/post/632873371/](http://archimedes.soup.io/post/632873371/))
> The c200 days of "rapid decreased flux" between Kepler-day 1100 and 1300
> (first half of 2012) which Monet/Simon reported, followed by a series of
> large dips after day 1500, would suggest a course correction with the space
> ship now on its final homing trajectory. -- Comments?_

\--
[https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont...](https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_montetjoshua_simon_paper/d65t063)

~~~
imaginenore
How can a ship 100 km in diameter cause any significant dimming of a star,
which is 21,980,000 km in diameter? It would have to be pretty close to here
and lined up just so perfectly.

Why even assume it's a spaceship and not an asteroid or a rogue planet?

~~~
jessaustin
The moon is smaller than the sun, and yet still we have eclipses. It's just a
matter of perspective.

The object[s] _would_ have to be lined up. That's why an artificial object
intentionally traveling to Earth is in some sense more plausible than an
asteroid, which could be headed in any direction.

~~~
vmarsy
Why would it be only one object? It could be a belt of random sizes and shaped
asteroids that is between us and the star?

~~~
Jill_the_Pill
Or the entire Vogon fleet?

------
singularity2001
Sunspots, debris and/or a distant cloud are not completely ruled out:
[https://arxiv.org/abs/1608.01316](https://arxiv.org/abs/1608.01316)

Wiki:

The leading hypothesis, based on a lack of observed infrared light, is that of
a swarm of cold, dusty comet fragments in a highly eccentric
orbit.[12][13][14] Many small masses in "tight formation" orbiting the star
have also been proposed.[9] The changes in brightness could be signs of
activity associated with intelligent extraterrestrial life building a Dyson
swarm.[9][15][16][17] The SETI Institute's initial radio reconnaissance of KIC
8462852, however, found no evidence of technology-related radio signals from
the star.

[https://en.wikipedia.org/wiki/KIC_8462852](https://en.wikipedia.org/wiki/KIC_8462852)

~~~
CamperBob2
Safe to say that a civilization that can build a Dyson structure isn't using
any 20th-century coherent modulation types that SETI could detect.

SETI is only useful for catching civilizations in the ~100 Earth year-
equivalent span between their development of wireless tech and information
theory. There's nothing to listen to but white noise after that.

~~~
seventytwo
This is speculation. There are all kinds of examples we have of "ancient"
technology that are still in everyday use today - knives, for example.

There's no reason to think that something else would abandon using EM as a
transfer of communication.

~~~
CamperBob2
That's not what I said. Tune a general-coverage receiver to the frequency of
an HDTV station, and what you hear is what the SETI folks will hear, whether
there's a signal there or not.

~~~
TeMPOraL
Also, from what I understand, the last several decades of our radio history
were spent optimizing everything so that signals keep as much to the ground as
possible - emitting TV into space is wasting money.

------
eudox
>What they saw was that, not only did the star's light output occasionally dip
by 20 percent - the weird behaviour scientists first spotted last year - but
over the course of the observations, its entire stellar flux actually dimmed.

It would be interesting if this turned out to be like the OnOff star from _A
Deepness in the Sky_.

------
ChuckMcM
I really like mysteries like this one. They defy simple explanations and force
us to work harder to learn more about our world. Sort of like the bright spots
on Ceres, which are still pretty awesome.

------
jhbadger
Reminds me of when quasars were first discovered and people thought they were
part of some alien telegraph system.

------
ianai
I find it funny that a clickbaity title like that bothers to tell people to
"not get too excited" about the possibility of anything involving aliens.
Further, you know what? I say this is something to be really fired up about.
We've got a phenomenon here that matches nothing we can come up with
theoretically. Live it up!

------
Symmetry
It's not like this is right on our doorstep but I'd still be more comfortable
if this was happening more than 1480 light years away.

~~~
lucb1e
Well whatever it is, we probably have 1000+ years to save ourselves right? If
whatever caused it comes at us at 50% light speed, which sounds unlikely given
how fast that already is, we'd still have 700 years.

I'm pretty sure that if human's resources were suddenly all turned towards
getting the hell out of here, we could certainly pull it off for a good part
of the population in a few hundred years. Whether we'd eventually survive,
after decades or centuries in space (before we manage to find and arrive at a
new planet, if any), is something I'm less certain about, but I'd still
estimate the odds to be fairly okay, especially with 1000+ years to prepare.

~~~
jerf
"Well whatever it is, we probably have 1000+ years to save ourselves right?"

No. That time has already passed. If we see signs that the star will go nova
"in one year", we have one year, not 1481.

The popular idea that we see "the past" in the sky is not really the best way
to think about it. It is far more accurate to say that there is no such thing
as "the" present, and what we see in the sky really is _our_ present. The view
that we're seeing "the past" is ironically perhaps less sophisticated than the
more naive idea that it is simply our present we are seeing in the sky. (And
at the moment, there aren't any other "presents" that we much care about.)

The thing that really saves us is that even supernovas that far away can't
really hurt us because of the inverse square law. A quick Google search shows
one site estimating that a supernova would have to be 50 ly or closer or so:
[http://www.howitworksdaily.com/could-a-supernova-destroy-
ear...](http://www.howitworksdaily.com/could-a-supernova-destroy-earth/)
Something would have to be beamed specifically at us, and the only natural
phenomena I know that can do that are black holes and pulsars, neither of
which seem to be what is at that star, and probably still wouldn't be powerful
enough to hurt us at that distance.

~~~
mjevans
From an intelligent life angle, what would really save us is that, aside from
a number of planets to observe, we haven't really been all that interesting
until the last 100-200 years; when we started actually emitting signs of
intelligent life in to space.

~~~
riffraff
Ah, but this is only true about we, humans rather than earth/solar system. It
cannot be excluded that other sources of radio have been around here in the
past :)

~~~
Normal_gaussian
It also assumes that outside observers have the same difficulty understanding
the make-up and probable evolution of a system as we do. If they were able to
observe that Earth would have some properties they were interested in, or
would be a likely candidate for such, then they wouldn't need us to announce
our presence to guess it.

~~~
mkstowegnv
IMHO the aliens will not be specifically seeking life that is intelligent.
Singularities and interstellar traveling alien civilizations share a problem.
If one is in essence immortal the only purpose that can endure forever is the
pursuit of new knowledge. Even if alien entities are able to learn all there
is to know about all the other sciences, biology will be inexhaustible as the
novel patterns that can be produced by evolution are effectively infinite. The
biosphere of just our planet where the latest estimates are that there are a
trillion species if you count all the microorganisms, probably contains more
information than all the lifeless planets and stars in the galaxy combined.
The aliens will value biodiversity more than we do. And if they arrive they
will oppress us "only" to the extent required to counteract our propensity to
cause species extinctions (including our suicidal alteration of the planet's
climate). I actually would prefer that the Singularity or the aliens arrive
sooner rather than later as I have less and less hope of our species getting
its act together on its own.

~~~
int_19h
>> biology will be inexhaustible as the novel patterns that can be produced by
evolution are effectively infinite

But why do you assume they would be interested in observing the patterns that
actually have been produced, instead of running high-precision evolutionary
emulators that can generate patterns that could be produced at a much higher
rate, and maybe even some automated filters to condense it down to
"interesting" stuff? It's still knowledge, and there's no innate value scale
for knowledge which says that things that have "actually happened" are more
valuable.

In fact, how's that for Fermi paradox? Civilizations that are sufficiently
technologically advanced to communicate, much less travel, across the stars,
are also sufficiently technologically advanced to simulate the things they are
interested about and get answers faster that way.

Basically, the end result of any civilization is creating, maintaining and
expanding a simulation of the universe. Which, of course, goes recursive...

~~~
Symmetry
Thermodynamics still limits what you can compute and, given the output of a
single star, you're still limited in what can be computed.

But I think it's a mistake to try to characterize any civilization by a single
motivation. People on Earth do things for many different reasons and I think
we should expect the same of alien civilizations even if single motivations
tax our imaginations less. The questions is if _any_ of the motivations
driving a stellar civilization would be enough to prompt the establishment of
colonies. I don't think you can say that the answer will be 'no' reliably for
every civilization that might arise and it only takes on to colonize a galaxy
in short order (by cosmic standards). Hence sophisticated life is probably
very rare.

------
soheil
In her TED talk [1] Tabby explains how comets could be an explanation for this
phenomenon, she even says that it is consistent with their observations, but
then she goes on to say "but it 'feels' a little contrived". Sorry what did I
miss here? I thought we were discussing science and coming up with theories
that support our evidence using data, how does feeling fit into this picture?

Why would it be so unlikely that a big comet swarm happens to be between us
and Tabby's star, a distance of 1500 light years!

Comets seem like a pretty good explanation, I haven't heard an argument
against them.

[1]
[https://youtu.be/IyIAjUuxNKw?t=7m17s](https://youtu.be/IyIAjUuxNKw?t=7m17s)

~~~
MichaelGG
A lot of evaluating a theory means making subjective judgements on the
probability of things if there's not perfect priors established. Like
debugging: You end up with things that could have a few ways of happening.
Nothing seems to line up perfectly. Different team members can make arguments
on what the most likely culprit is. If something doesn't feel right, then you
perhaps lean towards another hypothesis.

------
j_m_b
Could an astronomer weigh in as to why the dimming effect isn't due to a
'rogue' blackhole entering orbit with the star and both blocking light and
draining material from the star? I haven't seen that hypothesis dismissed yet.

~~~
simcop2387
Not entirely sure why, but I suspect because they haven't been able to
determine if there's any lensing going on of the star that you'd expect to see
if something like that entered the system. But I do believe that they'd see
higher energy (x-ray, gamma?) bursts if it was removing material from the star
which would lead to a different kind of variability. We know roughly what that
should look like because of other binary systems where one star is being
consumed and I don't think I've seen anyone say this looks a bit like that.

Though I'd love to have someone that's actually knowledgeable on the subject
to weigh in and tell me how wrong I have this.

~~~
antognini
There wouldn't be any observed lensing because you have to be the right
distance between the lens and the source for that to be observed. (For objects
of comparable mass, the lens has to be roughly halfway in between the source
and the observer) But if there were a black hole accreting matter from the
host star, there would be an accretion disk which would be visible in X-ray.

A black hole is also too small to explain the drop in brightness. That would
require something planet-sized, but a black hole is only about the size of a
city.

~~~
tazjin
Black holes are uniformly sized?

~~~
m_mueller
Stellar ones have a soft upper boundary. If they are so old and massive that
they become planetary or even stellar sized - well the'd start drawing
stealing a good chunk of the host galaxy and form their own one - with
blackjack and hookers. I.e. a flickering star would be the least of your
worries ;-).

~~~
ethanbond
What causes the soft upper boundary?

~~~
wbl
The mass of the star before it went and formed a black hole. The bigger a
star, the hotter it is, and the more evaporates from the surface, and the
shorter it lives. Large blackholes grow through things falling into them.

~~~
ethanbond
Oh I read the parent comment as _black holes_ having a soft upper boundary. Is
that the case? Or if more stuff falls in they just get bigger (minus Hawking
radiation)?

~~~
wbl
So there is a complication, which is space is filled with vast amounts of
nothingness. For a black hole to get bigger objects need to be on a collision
course with it, which is somewhat unusual. A black hole doesn't behave any
differently from the same mass as something not a black hole. So once a star
turns into a black hole, the accretion disk is usually remnants/maybe more if
it is in a nebula. Once that's gone, that's it for growth.

------
pilif
Anyone else thinking of the beginning of the utterly excellent "Pandora's
Star" by Peter F. Hamilton?

~~~
boznz
A Bit at the scarier end of the possibility curve one hopes!

------
dave_sullivan
What would it look like if a super dense object like a neutron star or black
hole were feeding off the star? We only "see" those dense objects when they
expel the material they were pulling in from their accretion disk as
relativistic jets, right? So if an object were just leeching mass from a star
but not (yet) expelling the material, would it just look like a dimming star?

This doesn't necessarily rule out aliens. It could be a post-singularity
society of virtual aliens living in a quantum computer, leaching energy
directly from the sun and periodically expelling waste material through
relativistic jets. Of course.

------
mjevans
I don't recall the previous discussions, but without outright ruling out
possibilities for things...

* If it is some structure being built at/around the star, has anyone done the math on the rate of such a structure occluding the star from us to match the observed rate of change?

* On a similar line of reasoning, what if the star were either being drained as a power source or caught in some kind of SG1 (that stargate TV series) level disaster?

To be clear, I don't think that they're likely, but I'd rather they were
eliminated for an obvious actual flaw instead of simply being unlikely.

------
gp7
Pretty cool that observed phenomena in space that can't yet be explained gets
so much attention in the media. When you step back a bit and stop thinking
about aliens

------
sbierwagen
Link to paper:
[https://arxiv.org/pdf/1608.01316v1.pdf](https://arxiv.org/pdf/1608.01316v1.pdf)

------
adrianratnapala
There is an epistamological conundrum involved in astronomy. In this case even
Jason Wright admits that theories involving alien-action are

> a “perilous approach to science”—one > that could lead to an “alien in the >
> gaps” fallacy, and unfalsifiable > hypotheses.

But on the other hand, if we always strain to find a non-alien answer to
everything we are in danger of making them up and distoring our ideas of what
can happen naturally.

------
Pica_soO
Could a extreme deforming by a another gravity corpus in a elliptic orbit
reduce the pressure necessary for fusion so much that the observed luminosity
drop could be explained?

------
T-A
It's obviously being eaten by black monoliths [1].

[1]
[https://en.wikipedia.org/wiki/2010:_Odyssey_Two](https://en.wikipedia.org/wiki/2010:_Odyssey_Two)

------
amelius
Could it have been hit by a large planet that lost its orbit somehow (perhaps
from another system)? (And out of interest, is this an event that has been
recorded before?)

~~~
sitkack
Are you saying we looking the edge end of an Accretion Disk[0] ?

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

Two planets collide, forming a huge mess, that mess continues to collide with
itself in a chain reaction. If the rings of saturn surrounded a star, what
would that star look like when viewed edge on? Do the rings precess? What can
we say about the size of the object in the ring and how will the ring
structure evolve over time?

------
perseusprime11
When Elon Musk and Jeff Bezos start building their mega structures around
Mars, some far away alien species will report a similar sighting about us.

------
mchahn
> dimming at such an incredible rate that it can't solely be explained by any
> of the leading hypotheses

So it must be aliens. That can explain anything.

------
JoeAltmaier
Being eaten from the inside out by a black hole?

------
s_q_b
We thought pulsars were alien transmissions for a while.

------
basicplus2
how about multiple nutating disks of debris who's centres are the star in
question.

------
bni
Maybe its the On/Off star

------
roberthahn
The dimming is probably a dark matter nebula passing between it and us.

~~~
ceejayoz
[https://en.wikipedia.org/wiki/Dark_matter](https://en.wikipedia.org/wiki/Dark_matter)

> The name refers to the fact that it does not emit or interact with
> electromagnetic radiation, such as light, and is thus invisible to the
> entire electromagnetic spectrum.

~~~
flukus
Couldn't it bend the light enough that it looks to be dimming to us?

~~~
ceejayoz
Gravitational lensing has pretty distinct other characteristics that would be
noticeable.

------
DiabloD3
Would plasma cosmology explain this?

~~~
messe
Not in the slightest.

------
aarmenante
> In the meantime, we would remind you that it's very, very unlikely that this
> strange flickering star has anything to do with aliens (and is even more
> exciting if it doesn't - because, hello new space phenomena!).

I think aliens would be a _little_ bit more exciting... Might just be me
though.

~~~
zackya89
that headline though ?, online journalism at its worst, the chase for clicks,
there really needs to be some solution to this problem journalism is dying and
clickbait is where is at.

~~~
civilian
"Extraordinary claims require extraordinary evidence", and this is the
weirdest star we've seen. Your claims of clickbait are out of line, because we
really don't know and alien megastructures is a reasonable theory.

And 'alien megastructures' isn't even the most ridiculous idea:
[https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont...](https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_montetjoshua_simon_paper/d65t063)

~~~
jimmytidey
This is an amazing theory. What could possibly be more out there than alien
life? Alien life in a gigantic spaceship accidentally coming between you and a
star.

~~~
api
Would it actually be a straight line?

Going from e.g. Earth to Mars does not consist of aiming for Mars and firing
your rockets. It consists of hitting a parabolic _transfer orbit_ and then
doing another burn to place yourself in Mars' orbit -- or just heading right
in if you've got the heat shields and retropropulsion for that. Basically you
do orbital mechanics like Wayne Gretzky: you don't go to where the planet is,
but where it's going to be.

Would interstellar flight be that different? Wouldn't you be executing a
"transfer orbit" about the galactic center? Or is the effect of galactic-scale
gravitational pull negligible there and you just end up basically going
straight from A to B?

Edit: turns out this came from an actual subreddit dedicated to this star!

[https://www.reddit.com/r/KIC8462852/](https://www.reddit.com/r/KIC8462852/)

Subscribed!

~~~
bitJericho
The galactic center is 100,000 lightyears away. Going from a location to
another 1000 lightyears away via the galactic center would make the trip 200
times longer. A 10,000 year journey would thus take 2 million years. It's
probably better to jump from point A to B, then.

~~~
kuschku
no, @api is right - you're orbiting the galactic center for a while.

Similar how transfer from earth to mars works via a solar orbit.

So, yes, you have to include orbital mechanics, not just straight lines.

~~~
bitJericho
I didn't say there's no need to consider orbital mechanics. I said taking a
route through the galactic center is not a realistic scenario.

~~~
api
I didn't mean through the center, just orbiting it. Look up a Hohmann
transfer. I was just saying it wouldn't be direct.

------
okket
Please correct the title, it is about a Tabby's star, not alien
megastructures.

~~~
sctb
Thanks, we updated the title. We're happy to change it again if someone can
suggest a better one.

------
Apocryphon
Pancreator deliver us, the suns fade.

------
djrogers
More accurately - it dimmed at an incredible rate ~1480 years ago and we are
just now seeing the light from that event.

