21st Century will comes with most amazing observation of Exo planet hunting methods and discoveries …
Towards KIC 8462852
NASA's Kepler mission changed the game, surveying over 100,000 stars for a period of many years. When a planet passes in front of its parent star, relative to our line-of-sight, some of the star's light will disappear for a short while and with repeating pattern like this , astronomer find many info about planet.
But during this observation, Astronomer stuck to one star name KIC 8462852 with getting dim of light but not like normal star in simpler words, when planet passes in front of star, it will dim less than 1% of star light, but with this star the dim is more than 20%. Surprising. Right..?
KIC 8462852
KIC 8462852 —Also known as either Tabby's/Bayesian’s star (after the discoverer of its interesting behavior, Tabetha Boyajian)
or the WTF? (for where's the flux?)
Astronomers observing this star from many years and here are some properties that they discover about this oddball of gas…
- Exhibits huge drops in its flux, by up to 22% (while most planets cause <1% dips),
- Fades slowly over timescales of decades with occasional brightening events (which no other, similar stars are known to do),
- Where the overall brightness fluctuates around the dips (rather than the smooth decrease-and-increase seen for planets),
- But with no infrared emission (which all other stars with large flux dips possess).
After the discoveries many astronomer predicts different types of hypothesis that makes it easy for us to understand this type of odd behavior, Let’s look at this one by one ..
Hypothesis
Bigger Planet
It could be planet bigger then we can imagine, May be bigger than our Jupiter (super Jupiter) but the problem is that if its planet, it should be periodical dip which doesn’t fit in this case because dimming is not periodically and repeating for specific amount of time ..
Protoplanetary disk
May be this cause by Protoplanetary disk that cause this dimming ? Well observation of star shows that, Star is many hundreds millions years old to remains the protoplanetary disk and most importantly, doesn't exhibit the infrared flux emission that a star with a protoplanetary disk ought to have. This is why the star was originally named the "WTF?" (for where's the flux?) star.
Cometary events
It could be a series of cometary events, where they emit large amounts of dust being kicked up as they infall onto the inner portion of the solar system (just like our solar system - comet or debris falling )but it observation shows that , this type of event are short term events where as this star’s dimming lasts for years again not fit in ..
Megastructures
The popular idea is that was advanced was that of alien megastructures: that a civilization far ahead of humanity, technologically, was constructing an apparatus that periodically blocked a large percentage of the star's light. As the structure became more and more complete, that would increase the amount of light that was blocked. Over the past century, the fact that the light from this star had dimmed by such a significant amount could be explained by an advance in how completed the structure would be. But an Alien megastructure would be completely opaque to light: it would be unable to pass through it. This is equally true of things like planets, moons, or any other "solid" objects you can imagine.
Finding Solutation through Observation
The solution of what causing this comes to light when astronomer measure it with different wave length band spectrum. Studying different parts of sky (the empty ones) we notice that blue light is preferentially blocked in all dimming events starting from the short-term flux dips to the long-term fading of the star. There's one thing known that can cause bluer light to be blocked while redder light is preferentially transmitted: dust particles that go down to at least a certain, minimal size.
Yes key is in Nanometers
And when Astronomer give more thoughts to more ideas and starting observation towards this, they are very surprise to find combination of few things that we don’t notice together, like ...
- It's consistent with having a large amount of circumstellar dust, which normally indicates an extremely young star still in the formative stages.
- The star itself is brighter, hotter, and more massive than the Sun: it gives off more than four times the amount of light our Sun does.
- The star is old: hundreds of millions of years old, burning stably on the main sequence by all accounts.
Observation (1890 appears to continue through the current 2018 data as shown below image) in brightness shows that it’s not steady dimming , In other words there are long-period dips lasting months, and shorter dips lasting a day or less superimposed on top of them. It's definitely due to dust particles, down to maybe about 100 nanometers in size. The ratio of how the light dims in different wavelengths/colors demonstrates that and rules out other hypotheses.
The scientists involved in this project calculated how much dust must be involved to explain the past 100+ years of dimming and dipping events. For what's merely in the transiting plane defined by our point-of-view alone, we need to have an amount of dust equal to about the mass of the Moon.
So when astronomers find the answer of fading, next question is that what causes this..?
Dust is Conformerd but what causes Dust ?
- First one suggest that, it must be an interstellar dust starting from inner dust of system to spreading towards outwards, which is not close enough to emit infrared radiation. Comets, too, should create infrared radiation ..
- If a gas giant planet may be the size of Uranus were devoured by this star, it could be the culprit. An inspiral of a planet or a series of planetary bodies a long time ago, perhaps centuries or even many millennia ago, could have caused a temporary brightening, from which the star is now returning to its original, stable state. The flux dips we observe, then, could be due to planetary debris from an earlier disruption, or evaporation and outgassing of smaller bodies.
But we are still not sure about which is the cause, the James Webb Space Telescope should be able to tell, when the flux dips occur, whether the comet hypothesis is in or out.
One thing is certain
the reason is for the dimming of Bayesian’s star is due to dust. This is normal, particulate dust, containing particle sizes down to about 100 nanometers, or smaller than the wavelength of visible light. The same dust that causes short, day-or-less dips also causes dips that last many months, and also cause the decline that's lasted more than a century. It's all due to plain, normal dust.
Thank You Ritu Yadav (one of my follower from India) for requesting this amazing topic, I had really fun in searching and writing about it . If you have any topic suggestion DM me on my social media account or email me @astronomy.for.me.7337@gmail.com