# Thread: Hubble discovers record-breaking quasar

1. ## Hubble discovers record-breaking quasar

"Astronomers said it is by far the brightest quasar discovered so far in the early universe."

https://news.sky.com/story/hubble-fi...-suns-11603311

3. ## Re: Hubble discovers record-breaking quasar

Mind boggling!!!

The brightness of 600 trillion suns!
10 000 new stars a year!
Wow!

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chas53 (01-11-2019)

5. ## Re: Hubble discovers record-breaking quasar

If my calculations are correct, then at the distance of M31 it would be much brighter than Venus, mag ~ -7.7

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chas53 (01-11-2019)

7. ## Re: Hubble discovers record-breaking quasar

Originally Posted by pikaia
If my calculations are correct, then at the distance of M31 it would be much brighter than Venus, mag ~ -7.7
I'm getting a somewhat different result at ~ -2.6.....

Here's how I did my calculation:

M31 is magnitude 3.4 with 1 trillion stars. This beast has 600 trillion so should be ~600 times brighter that's about ~ 7 magnitudes giving ~ -2.6.

Still a stunner.....

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chas53 (01-11-2019)

9. ## Re: Hubble discovers record-breaking quasar

Here's a different take on the same object.

https://phys.org/news/2019-01-cosmic-telescope.html

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chas53 (01-11-2019)

11. ## Re: Hubble discovers record-breaking quasar

Here's one way to calculate it: M31 has absolute magnitude - 21.5, versus 4.8 for the sun, a difference of 26.3 magnitudes, or about 3 x 10^10.
The quasar is therefore 20000 times brighter, or nearly 11 magnitudes. 3.4- 11 = -7.6.

The average star in M31 seems to be much dimmer than the Sun, which would explain your different result.

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chas53 (01-11-2019)

13. ## Re: Hubble discovers record-breaking quasar

The math thing is interesting but even more interesting is the sheer magnitude of the quasar and that it is a trillion times brighter than our star and that it generates 10,000 new stars a year and the black hole is so massive it is mind boggling. I am totally in awe. And that it is so old. This whole thing is stupefying. Thanks for sharing the link.

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chas53 (01-11-2019)

15. ## Re: Hubble discovers record-breaking quasar

Originally Posted by pikaia
Here's one way to calculate it: M31 has absolute magnitude - 21.5, versus 4.8 for the sun, a difference of 26.3 magnitudes, or about 3 x 10^10.
The quasar is therefore 20000 times brighter, or nearly 11 magnitudes. 3.4- 11 = -7.6.

The average star in M31 seems to be much dimmer than the Sun, which would explain your different result.
There are many uncertainties with this kind of projection. I think that my estimate illustrates some of the uncertainties.

Your estimate takes the absolute magnitude of M31 to be -21.5 which is visual, not bolometric (all wavelength) for instance. Then there is a redshift factor that shifts the spectrum to the red that has to be accounted for.

It's an excellent point you raise is the nature of the "average star". What that means isn't clear from the articles. But we do know that early in the universe stars had less metals so the upper limit on mass was much higher more like 200-300 Msun. So the "average star" in this object could be much brighter than the sun.

600 trillion Lsun is brighter than 4.8 by 37 magnitudes for -32 absolute magnitude which keying off M31 again gets ~ -7.1 neglecting differences in visual and bolometric magnitudes.

Given all the uncertainties ( visual versus bolometric, red shift reddening corrections, average star and metallicity issues) I think the uncertainty in the estimate could be as much as several magnitudes. That's all. Perhaps -7 +/- 2 is fair.
Last edited by not_Fritz_Argelander; 01-10-2019 at 06:03 PM.

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chas53 (01-11-2019)

17. ## Re: Hubble discovers record-breaking quasar

Here's another link on the complications of making the estimate of what it would look like close up. It's a mess.

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chas53 (01-11-2019)

19. ## Re: Hubble discovers record-breaking quasar

You know, it occurred to me late in the day that the 10,000 stars made a year has amusing implications. The articles aren't clear but galaxy star formation rates are usually quote in solar masses of gas and dust converted to stars per year. Whether or not the authors followed this common practice this star formation rate implies that the supernova rate has to be a few per year.

That would be interesting fireworks to be sure......

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chas53 (01-11-2019)

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