Tabby's star is dimming at an incredible rate • Hacker News Board

Re: Tabby's star is dimming at an incredible rate

#91

Post by bitJericho » Sat, Aug 06, 2016, 11:04 PM UTC

kuschku wrote: post #82

bitJericho wrote: post #72

Earlier quoted context omitted.

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.

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.

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.

Re: Tabby's star is dimming at an incredible rate

#92

Post by throwaway_yy2Di » Sat, Aug 06, 2016, 11:08 PM UTC

civilian wrote: post #40

zackya89 wrote: post #16

Earlier quoted context omitted.

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.

"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...

That can't physically work: for one because the parallaxes would be different and almost never line up. If something's colinear with a star today, it won't be colinear 6 months later, when the Earth's on the other side of the sun.

At 2 light years for instance, that spacecraft would trace an apparent ellipse 3.3" in diameter, while Tabby's star (1,480 ly) would be stationary (0.004" parallax). In comparison, the star's apparent disk is just 30 μas wide (0.00003").

Re: Tabby's star is dimming at an incredible rate

#93

Post by TheOtherHobbes » Sat, Aug 06, 2016, 11:14 PM UTC

sitkack wrote: post #79

Zardoz84 wrote: post #74

Earlier quoted context omitted.

Spectral type isn't 1-1 correlate with the star estimated life. Depends on the star mass. Our Sun was one time a F type star.

Question for you Timex Eclair, can I use a star as the engine for my megaship? Pointing all the photons in direction?

Like this?

Of course if this was happening we'd see some unusual proper motion from KIC 8462852. Which we're not. (Did someone check?)

Re: Tabby's star is dimming at an incredible rate

#94

Post by dave_sullivan » Sat, Aug 06, 2016, 11:20 PM UTC

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.

Re: Tabby's star is dimming at an incredible rate

#95

Post by nine_k » Sat, Aug 06, 2016, 11:20 PM UTC

noiv wrote: post #33

zackya89 wrote: post #16

Earlier quoted context omitted.

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.

I hope one day title bashing turns into a global no-ads movement.

A global "we pay for the content" movement? Would be interesting.

Re: Tabby's star is dimming at an incredible rate

#96

Post by soheil » Sat, Aug 06, 2016, 11:27 PM UTC

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

Re: Tabby's star is dimming at an incredible rate

#97

Post by Retric » Sat, Aug 06, 2016, 11:36 PM UTC

soheil wrote: post #96

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…

Thousands of comets in just the right spot or tens of thousands of comets over a small area just for that star which seems contrived.

If you can create a credible reason why there might be a swarm of comets like this say as remnants from a collision between a large body with just the right orbit* then that's just 1 event which is more plausible.

*And I don't mean me saying it, actually create a model that would result in it based on you know math.

Re: Tabby's star is dimming at an incredible rate

#98

Post by throw_away_777 » Sat, Aug 06, 2016, 11:43 PM UTC

soheil wrote: post #96

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…

It probably is comets, but why the comets are in the position they are in is not well described.

Science is done by people, and it is often very challenging or impossible to rigorously quantify exactly how unlikely something is. This is especially true in observational science. Furthermore, in communicating results to the public it isn't necessarily helpful to speak with quantitative rigor because the audience doesn't care. If someone says this has a 1 in a 10000 chance of being due to aliens, the headlines will scream "Scientists say alien life could be found!"

Re: Tabby's star is dimming at an incredible rate

#99

Post by throwaway_yy2Di » Sat, Aug 06, 2016, 11:43 PM UTC

fjarlq wrote: post #42

simcop2387 wrote: post #18

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/KIC8462852/comments/4w7qfi/ben_mont... They also contain links to the resulting paper itself

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 h…

    can it be easily ruled out?

Yes: parallax breaks it. If something's colinear with a star today (and occults it), it won't be colinear 6 months later, when the Earth's on the other side of the sun.

At 2 light years for instance, that spacecraft would trace an apparent ellipse 3.3" in diameter, while Tabby's star (1,480 ly) would be stationary (0.004" parallax). In comparison, the star's apparent disk is just 30 μas wide (0.00003").

Re: Tabby's star is dimming at an incredible rate

#100

Post by MichaelGG » Sat, Aug 06, 2016, 11:44 PM UTC

soheil wrote: post #96

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 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.