ED Hertzsprung-Russell diagram

malenfant

M
(this is an offshoot from this thread: https://forums.frontier.co.uk/index.php?threads/red-giant-or-not-red-giant.510896/ )

I tried doing a plot of Stellar Temperature (x axis) vs Log L on the y axis - calculated from Abs Mag by L = 10^((4.83 - M)/2.5)) - for the 5000 or so stars I've catalogued in ED (excluding neutron stars and black holes, which are way off the chart or break it). Since the y axis is Log L that means 0 is 1 LS, 2 is 100 LS, 4 is 10,000 LS etc, and -2 is 0.01 LS, -4 is 0.0001 LS, etc.

It doesn't quite look the same as the classic H-R diagram... but it's kinda similar? The long line is the main sequence. The short thick line below it seems to be White Dwarfs, and the shorter thin line above the middle seems to be M Red Giants. Not sure what the other bits outside the main sequence are yet (e.g. the curve above it at the top left, and the cluster between the MS and WDs) but I can investigate later.

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I also could attempt to colour these according to stellar type etc later, this was just a quick and nasty attempt to plot what I had. It also includes Os and Ws at top left of the main sequence and LTY at bottom right.
 
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malenfant

M
So is your graph saying that Herbigs are found at all stellar masses? They should only be proto-O/B/A stars (with appropriately high masses).
 

Orvidius

Orvidius
Technically the graph is absolute magnitude vs surface temperature only, so if they cheated and had totally inappropriate masses for those values, then we wouldn't be able to draw any conclusions about mass from the graph. :)

However, in the data, the Herbigs range in mass from 3.00391 to 119.98 solar masses. So, sort-of. ;) The mass range is appropriate for O/B, but not really A.

EDIT: I wonder if I made the WR stars a little too similar in color. They're more blue in the color key, rather than purple. Those are ranging from 0.46875 to 119.996 solar masses.
 
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Orvidius

Orvidius
Some additional stats on the Herbigs:

Surface temperature ranges from 3353 to 6034
Abs. Magnitude ranges from 4.69864 to 12.1491

These should be the narrow purple band right in the middle underneath the main sequence.

EDIT: The larger purple band that covers the whole range appears to be the WR stars.
 
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malenfant

M
That's even weirder then, because Wolf-Rayet stars should all be (a) rare and (b) above and to the left of O. They're very bright, very blue and very massive (though I know ED screws that up since there are definitely some cold red ones).
 

Pirin

Pirin
Impressive work!
But i wonder if you should include WRs at all. Their temperatures seem completely random and unrealistic. Some are as cold as 25-30C. I could walk on their surfice without sweating :) I am not an astronomer but that doesnt seem right.
 
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