Wandering through the realms of the cosmos, pondering its huge vastness

Massive Mega-Star Challenges Black Hole Theories

I would just like to share this article which I’ve seen recently on the internet. :D

It primarily calls into question an important thing which we know about black holes — their formation particularly how massive a star is supposed to be to develop into one.

I find it amusing not only because I’m interested in black holes but also because it somewhat imparts a valuable lesson for a lot people.

“Don’t believe everything you read in [astronomy] books.. as soon as they’re written, many details quickly become out of date..”

We should always try to keep updated about all the new stuff and discoveries around us. This is how science works. Science is open to change based on new evidence. As long as we stay curious about things, what we know about the universe will change as we learn new things.

The Universe is more complicated and more interesting than we first thought. That is always cool. :D

* * *

(click title above to see the full article)

Sometimes there are news stories with so much awesomeness to them it’s hard to describe it all. This is one such item. It starts with a bruiser of a star cluster, and ends with astronomers scratching their heads over black holes.

Awesome thing #1:

Westerlund 1, a massive star cluster about 16,000 light years away

Here’s the cluster as seen by the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile:

Awesome thing #2:

In the image, two stars are marked. At the lower left is a circle marking the location of a magnetar, the actual star (haha!) of our story. Magnetars are a little bit scary. They are extremely dense, super-magnetic stars that can form from supernova explosions.

Awesome thing #3:

Another star is indicated in the picture above. It’s called W13, and it’s a binary, two stars orbiting each other (they’re so close together they appear as one star in the image). That’s very important! Hundreds of years ago, astronomer Johannes Kepler figured out that if you can observe two objects orbiting each other — a planet around a star, a moon around a planet, or even two stars circling — you can calculate their masses. It’s a standard technique we’ve been using for a long time.

From that idea, we have directly measured the mass of a star in the cluster Westerlund 1, and it has 40 times the mass of the Sun.

Awesome thing #4:

We also know that there exists in the cluster a star with about 35 times the mass of the Sun, and it started with about 40. We can therefore be pretty sure that any star more massive than that would’ve exploded by now, and also that any star that already has exploded would have started off more massive than that, too.

But we also see a magnetar in the cluster. That means the star that formed it must have had a mass of at least 40 times the mass of the Sun or so!

Uh oh. That’s trouble. And that’s why this is awesome. All the evidence points to the fact that we’re really not quite so sure how massive a star can be to form a neutron star. And that means we’re also not so sure how massive a star has to be to form a black hole. When I give talks about this, I usually say a star more massive than about 20 times the mass of the Sun forms a black hole. What this star is telling us is that it’s not quite so simple.

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original source: ESO.org


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  1. Pingback: World Wide News Flash

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