2009: "Hertzsprung-Russell Diagram"

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NotAllThere
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2009: "Hertzsprung-Russell Diagram"

Postby NotAllThere » Wed Jun 20, 2018 4:52 pm UTC

Image

Alt text: The Hertzsprung-Russell diagram is located in its own lower right corner, unless you're viewing it on an unusually big screen.

I couldn't find this in the list. It must be there, musn't it? I mean explainxkcd already has an entry... And I don't get the title text at all.
Last edited by gmalivuk on Wed Jun 20, 2018 4:59 pm UTC, edited 1 time in total.
Reason: fixed the link
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby NotAllThere » Wed Jun 20, 2018 4:54 pm UTC

Did the rapture hit? I'm paranoid I know, but am I paranoid enough?!
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby cellocgw » Wed Jun 20, 2018 4:57 pm UTC

Disappointed that a few things didn't make the chart.

-- nice cold bottle of beer
-- bucket of liquid nitrogen
-- your mama
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby madaco » Wed Jun 20, 2018 4:58 pm UTC

So, the joke is that these diagrams are usually for stars, but here other things are being included?
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby gmalivuk » Wed Jun 20, 2018 5:00 pm UTC

NotAllThere wrote:Image
I don't get the title text at all.

The image itself has a luminosity and effective temperature if you're viewing it on a computer monitor. That monitor itself (or more precisely the portion of that monitor displaying the image) would be at the lower right corner of this diagram.

Unless you had a particularly large monitor, in which case the luminosity would be higher.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby da Doctah » Wed Jun 20, 2018 7:32 pm UTC

Where on this diagram would you place Dr Manhattan?

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby cellocgw » Wed Jun 20, 2018 7:58 pm UTC

da Doctah wrote:Where on this diagram would you place Dr Manhattan?


Just below Dr. Bronx .
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby zjxs » Wed Jun 20, 2018 7:59 pm UTC

gmalivuk wrote:
NotAllThere wrote:Image
I don't get the title text at all.

The image itself has a luminosity and effective temperature if you're viewing it on a computer monitor. That monitor itself (or more precisely the portion of that monitor displaying the image) would be at the lower right corner of this diagram.

Unless you had a particularly large monitor, in which case the luminosity would be higher.


I understand everything on here except for whales and astronomers. How do they emit luminosity?

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby gmalivuk » Wed Jun 20, 2018 8:00 pm UTC

body heat
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Sableagle » Wed Jun 20, 2018 8:17 pm UTC

Also bioluminescent plankton and smartphones.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Cousj001 » Wed Jun 20, 2018 8:32 pm UTC

zjxs wrote:I understand everything on here except for whales and astronomers. How do they emit luminosity?

gmalivuk wrote:body heat

Sableagle wrote:Also bioluminescent plankton and smartphones.


Drat, I see my idea of making a fortune by selling smartphones to whales has already been though of.
Last edited by Cousj001 on Wed Jun 20, 2018 8:42 pm UTC, edited 2 times in total.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Soupspoon » Wed Jun 20, 2018 8:34 pm UTC

Cousj001 wrote:Drat, I though my idea of making a fortune by selling smartphones to whales as already been though of.

[cetacean needed]

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Old Bruce » Wed Jun 20, 2018 9:27 pm UTC

Soupspoon wrote:
Cousj001 wrote:Drat, I though my idea of making a fortune by selling smartphones to whales as already been though of.

[cetacean needed]

Okay, a grudgingly given Internets to Soupspoon, grudgingly given because I should have thought of that first. [grudge-face emoticon]

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Reka » Wed Jun 20, 2018 10:41 pm UTC

Soupspoon wrote:
Cousj001 wrote:Drat, I though my idea of making a fortune by selling smartphones to whales as already been though of.

[cetacean needed]

THWACK! THWACK THWACK THWACK THWACK THWACK!

Also, +1 internets, but THWACK.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby XbHW_TestEngr » Thu Jun 21, 2018 12:29 am UTC

So what he's really saying is "astronomers aren't very bright".
While they are slightly hotter than a blue whale, they just don't shine.

And the battle between the sciences continues. (Hmmm ... that was in a previous comic ... too lazy to look.)
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby qvxb » Thu Jun 21, 2018 12:33 am UTC

Speaking of Body Heat, Kathleen Turner is about 10000 K.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby miturian » Thu Jun 21, 2018 7:53 am UTC

there's an error on there, right? the arrow in the x-axis should be pointing to the left.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Dave Rogers » Thu Jun 21, 2018 9:20 am UTC

NotAllThere wrote:Alt text: The Hertzsprung-Russell diagram is located in its own lower right corner, unless you're viewing it on an unusually big screen.


This is, of course, known as Hertzsprung-Russell's Paradox.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Sableagle » Thu Jun 21, 2018 9:24 am UTC

... and Nanase? She's a lot smaller than the Moon, but shines very brightly indeed ...
... and is hot.


There's an empty space between the cooler Supergiants and the cooler main sequence stars. Why's there an empty space?
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Sandor » Thu Jun 21, 2018 10:00 am UTC

Surely an LED bulb has a lower effective temperature than a normal (incandescent) light bulb. They have about the same surface area, but an LED bulb emits less total EM radiation. LEDs only look "hot" because their spectrum is so different to that of a black body.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby cellocgw » Thu Jun 21, 2018 11:20 am UTC

Sandor wrote:Surely an LED bulb has a lower effective temperature than a normal (incandescent) light bulb. They have about the same surface area, but an LED bulb emits less total EM radiation. LEDs only look "hot" because their spectrum is so different to that of a black body.


Not clear what you mean by "effective temperature." and don't call me Shirley.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby speising » Thu Jun 21, 2018 11:49 am UTC

cellocgw wrote:
Sandor wrote:Surely an LED bulb has a lower effective temperature than a normal (incandescent) light bulb. They have about the same surface area, but an LED bulb emits less total EM radiation. LEDs only look "hot" because their spectrum is so different to that of a black body.


Not clear what you mean by "effective temperature." and don't call me Shirley.


first google hit wrote:effective temperature
noun
Physics

noun: effective temperature; plural noun: effective temperatures

the temperature of an object calculated from the radiation it emits, assuming black-body behaviour.


yeah, i wondered about the definition of this, too. effective temp is not actual temp, as i (and Sandor it seems) would have assumed, but the effect measured in blackbody temp it has based on its radiation.

so a 6000K LED has a high effective temp although it probably isn't actually warmer than 300K.

.
.
.
why is a Blue Whale more luminous than an astronomer?

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Soupspoon » Thu Jun 21, 2018 12:05 pm UTC

speising wrote:why is a Blue Whale more luminous than an astronomer?
Because blue whales can't turn a light-switch off when it wants to whale, but an astronomer often does when wanting to astron?

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Raidri » Thu Jun 21, 2018 12:21 pm UTC

Soupspoon wrote:
speising wrote:why is a Blue Whale more luminous than an astronomer?
Because blue whales can't turn a light-switch off when it wants to whale, but an astronomer often does when wanting to astron?

A whale has a greater surface area so he emits more radiation.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Soupspoon » Thu Jun 21, 2018 1:14 pm UTC

Raidri wrote:
Soupspoon wrote:
speising wrote:why is a Blue Whale more luminous than an astronomer?
Because blue whales can't turn a light-switch off when it wants to whale, but an astronomer often does when wanting to astron?

A whale has a greater surface area so he emits more radiation.

And light switches would be far more fiddly. I think that's the most important point. They really couldn't flip a teeny light switch with their flippers. They might be able to swipe it with their tail, but that would still be down to a huge fluke.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby trpmb6 » Thu Jun 21, 2018 1:32 pm UTC

When looking at this you really have to consider surface areas.

Which is why I was at first a little confused as to the positioning of France. But had to remember the scale of the Luminosity axis. That's why France-Europa-Moon-Earth-Venus-Jupiter seems a little odd at first.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby itaibn » Thu Jun 21, 2018 1:51 pm UTC

Soupspoon wrote:
Cousj001 wrote:Drat, I though my idea of making a fortune by selling smartphones to whales as already been though of.

[cetacean needed]

Citation: The entry on Atlantic humpback dolphin in Wikipedia's List of cetacean species.

Also, I'm getting tired of digs on the intelligence of astronomers.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Soupspoon » Thu Jun 21, 2018 2:11 pm UTC

itaibn wrote:Also, I'm getting tired of digs on the intelligence of astronomers.

The only digs I've seen have been around archaeologists!

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Muswell » Thu Jun 21, 2018 6:05 pm UTC

Why is Great A'Tuin not on here?

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Archgeek » Thu Jun 21, 2018 6:59 pm UTC

Muswell wrote:Why is Great A'Tuin not on here?

Heck, where's Eärendil with his silmaril aboard Vingilótë? 'Not sure where an elven spaceship falls thermally, but the silmarils were widely known for their luminosity.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby Sableagle » Thu Jun 21, 2018 7:40 pm UTC

Archgeek wrote:
Muswell wrote:Why is Great A'Tuin not on here?

Heck, where's Eärendil with his silmaril aboard Vingilótë? 'Not sure where an elven spaceship falls thermally, but the silmarils were widely known for their luminosity.

He's a little busy helping the Free Peoples reclaim mordor at the moment, making his luminosity extremely hard to measure. We know from examining the stats of the gear people are using there that the luminosity of Eärendil is quantum. We just don't have a way of calculating the total number of those quanta.
If two Champions on two different world servers each use a cuirass with 10 Light of Eärendil, are they between them wearing 20, or are they wearing the same 10 in superposition, with those 10 existing on one world or the other, depending to which server you connect to check?
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby SuicideJunkie » Fri Jun 22, 2018 4:45 pm UTC

Sableagle wrote:There's an empty space between the cooler Supergiants and the cooler main sequence stars. Why's there an empty space?
Because a cool star on the main sequence is also a very small star and vice versa (red dwarfs). A supergiant, as the name implies, is quite large.
With both being at the same blackbody temperature, that size difference translates to a huge area difference and a huge luminosity difference.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby orthogon » Sun Jun 24, 2018 11:05 am UTC

Soupspoon wrote:
Raidri wrote:
Soupspoon wrote:
speising wrote:why is a Blue Whale more luminous than an astronomer?
Because blue whales can't turn a light-switch off when it wants to whale, but an astronomer often does when wanting to astron?

A whale has a greater surface area so he emits more radiation.

And light switches would be far more fiddly. I think that's the most important point. They really couldn't flip a teeny light switch with their flippers. They might be able to swipe it with their tail, but that would still be down to a huge fluke.

Two whale-related puns in one week? You've b[al]een told.
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Re: 2009: "Hertzsprung-Russell Diagram"

Postby PM 2Ring » Mon Jun 25, 2018 9:42 pm UTC

Sandor wrote:Surely an LED bulb has a lower effective temperature than a normal (incandescent) light bulb. They have about the same surface area, but an LED bulb emits less total EM radiation. LEDs only look "hot" because their spectrum is so different to that of a black body.

It seems strange to me to see someone calling incandescent bulbs normal. The sale of incandescent bulbs was banned here in Australia almost a decade ago. At least, the traditional incandescent filament bulbs were banned, you can still get some halogen type bulbs. Most domestic light bulbs here are now compact fluorescents, or LEDs. The old incandescent traffic lights were replaced by LEDs shortly before the ban took effect. I guess we'll be getting LED street lights at some stage, currently they're some form of metal halide lamp.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby smprather » Tue Aug 21, 2018 2:04 pm UTC

miturian wrote:there's an error on there, right? the arrow in the x-axis should be pointing to the left.


Hello fellow 1-poster. Yep. I came here to point out the same thing. I was at first confused about why the hydrogen bomb was on the far left at 100e6K.

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Re: 2009: "Hertzsprung-Russell Diagram"

Postby rmsgrey » Tue Aug 21, 2018 5:36 pm UTC

smprather wrote:
miturian wrote:there's an error on there, right? the arrow in the x-axis should be pointing to the left.


Hello fellow 1-poster. Yep. I came here to point out the same thing. I was at first confused about why the hydrogen bomb was on the far left at 100e6K.


The short answer is "tradition".

The H-R diagram was originally absolute magnitude against spectral class, with spectral classes going O,B,A,F,G,K,M,L,T with decreasing temperature, so you get a downwards slope. And when the scale got refined to use temperature rather than spectral classes, it stayed the "wrong" way round.


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