May 21, 2017 03:46 AM
Live look at the 'alien megastructure' star may solve mysteries
https://www.engadget.com/2017/05/20/live...ture-star/
EXCERPT: Astronomers may have ruled out an alien megastructure as the likely cause behind KIC 8462852's strange dimming, but it's still mysterious -- and that's partly due to the lack of live data (as live as you can get for a star 1,277 light years away, at least). How do you understand what's going on when you have to rely solely on historical info that doesn't even account for the star's spectrum? Thankfully, researchers are getting that big chance: they've caught the star in mid-dimming, and they have numerous telescopes trained on it. If they can record the spectrum before and after the oddball behavior, they may have a better idea of the root cause....
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The Star That Probably Doesn't Have an Alien Megastructure (But Maybe it Does) is Dimming Again
https://www.universetoday.com/135644/sta...e-dimming/
EXCERPT: [...] In other words, if we’re dealing with entirely natural phenomena – like clouds of debris, comets, a consumed planet or anything other than an alien megastructure – that will become clear from the spectra we obtain from the star. If, however, the spectra does not conform to these parameters, we will once again be back to speculating about the possible cause. And you can bet your bottom dollar the alien megastructure crowd will be out in full force! As Wright went on to explain, during the preceding week, there were indications that something was happening around the star. However, none of it was significant enough for observatories to go from “yellow alert” – i.e. in a heightened state of readiness – to actively training their telescopes on the star. The reason for this is that telescopes have their observation time scheduled weeks or even months in advance....
The stellar evolution conspiracy (part I)
https://astrobites.org/2017/04/30/the-st...cy-part-i/
The stellar evolution conspiracy (part 2)
https://astrobites.org/2017/05/20/the-st...y-part-ii/
EXCERPT: [...] Now, I don’t want to sound like a conspiracy theorist or anything, but this is something that is keeping some of us awake at night. Let’s start with the Achilles’ Heel of modern astrophysics: ages of stars. Except for very special cases, stellar ages are particularly tricky to measure because stars change very little throughout their lifetimes. To complicate things further, small changes in the interior structure of a star can produce significant changes in its surface chemical composition. This is why we need our models to be very accurate so that we can have decent estimates of the physical properties of stars (notice that I said “decent”, and not “good”).
There are many stellar evolution models out there and they are very similar, but it is not clear if any of them are even correct. For starters, it is practically impossible to compute stellar evolution from the first principles of physics, which is why we have to appeal to a series of simplifications and assumptions. Different authors apply different theoretical shortcuts, leading to the emergence of different models....
https://www.engadget.com/2017/05/20/live...ture-star/
EXCERPT: Astronomers may have ruled out an alien megastructure as the likely cause behind KIC 8462852's strange dimming, but it's still mysterious -- and that's partly due to the lack of live data (as live as you can get for a star 1,277 light years away, at least). How do you understand what's going on when you have to rely solely on historical info that doesn't even account for the star's spectrum? Thankfully, researchers are getting that big chance: they've caught the star in mid-dimming, and they have numerous telescopes trained on it. If they can record the spectrum before and after the oddball behavior, they may have a better idea of the root cause....
- - - - - - - -
The Star That Probably Doesn't Have an Alien Megastructure (But Maybe it Does) is Dimming Again
https://www.universetoday.com/135644/sta...e-dimming/
EXCERPT: [...] In other words, if we’re dealing with entirely natural phenomena – like clouds of debris, comets, a consumed planet or anything other than an alien megastructure – that will become clear from the spectra we obtain from the star. If, however, the spectra does not conform to these parameters, we will once again be back to speculating about the possible cause. And you can bet your bottom dollar the alien megastructure crowd will be out in full force! As Wright went on to explain, during the preceding week, there were indications that something was happening around the star. However, none of it was significant enough for observatories to go from “yellow alert” – i.e. in a heightened state of readiness – to actively training their telescopes on the star. The reason for this is that telescopes have their observation time scheduled weeks or even months in advance....
The stellar evolution conspiracy (part I)
https://astrobites.org/2017/04/30/the-st...cy-part-i/
The stellar evolution conspiracy (part 2)
https://astrobites.org/2017/05/20/the-st...y-part-ii/
EXCERPT: [...] Now, I don’t want to sound like a conspiracy theorist or anything, but this is something that is keeping some of us awake at night. Let’s start with the Achilles’ Heel of modern astrophysics: ages of stars. Except for very special cases, stellar ages are particularly tricky to measure because stars change very little throughout their lifetimes. To complicate things further, small changes in the interior structure of a star can produce significant changes in its surface chemical composition. This is why we need our models to be very accurate so that we can have decent estimates of the physical properties of stars (notice that I said “decent”, and not “good”).
There are many stellar evolution models out there and they are very similar, but it is not clear if any of them are even correct. For starters, it is practically impossible to compute stellar evolution from the first principles of physics, which is why we have to appeal to a series of simplifications and assumptions. Different authors apply different theoretical shortcuts, leading to the emergence of different models....