Universe Sandbox 2.1.4 Now Available - December 17

[atomic7732]

I vote for Kelvin, as default. For science!

How about all three?

I didn't exclude the others. I just said as default.

Although I am personally offended by other units.

Rankine all the way! *shot*

[Dan Dixon]

Also luminosity has no affect at this time, although star temp and luminosity would generally go hand in hand so to speak.

I remember why I hadn't gotten this to work before. It's a hard problem to make all these variables accurately relate to each other.

I hope to release another update this week that addresses this issue (so that when you change the temperature (with the diameter locked) it correctly updates the luminosity and mass.

[FiahOwl]

Also luminosity has no affect at this time, although star temp and luminosity would generally go hand in hand so to speak.

I remember why I hadn't gotten this to work before. It's a hard problem to make all these variables accurately relate to each other.

I hope to release another update this week that addresses this issue (so that when you change the temperature (with the diameter locked) it correctly updates the luminosity and mass.

But what about non-main sequence stars?

[Dan Dixon]

That's a

But what about non-main sequence stars?

Good question.

I'm toying around with allowing the user to set the Mass-Luminosity power value (where 3.5 works for the main sequence stars which are 90% of all stars). But this does feel about bit clunky.

Any thoughts on this or a better way to calculate mass from temperature, luminosity, and/or radius?

What is the Mass-Luminosity law?
http://csep10.phys.utk.edu/astr162/lect/binaries/masslum.html

The attached image shows my progress (although the Mass-Luminosity power value isn't visible). Any thoughts on how to better represent these options?

[vh]

Maybe a seperate box with a ratio and several presets. You would be able to fill in a number or use a drop-down box to select either white dwarf, main sequence, giant, supergiant, and whatever else.

I don't know. It sounds a bit like what you're doing with the "clunky" power value. Would having preset values make it simpler?

[FiahOwl]

use a drop-down box to select either white dwarf, main sequence, giant, supergiant, and whatever else.

I vote this.

[FiahOwl]

    0 hypergiants
    I supergiants
        Ia-0 (hypergiants or extremely luminous supergiants (later addition)), Example: Eta Carinae (spectrum-peculiar)
        Ia (luminous supergiants), Example: Deneb (spectrum is A2Ia)
        Iab (intermediate luminous supergiants) Example: Betelgeuse (spectrum is M2Iab)
        Ib (less luminous supergiants)
    II bright giants
        IIa, Example: β Scuti (HD 173764) (spectrum is G4 IIa)
        IIab Example: HR 8752 (spectrum is G0Iab:)
        IIb, Example: HR 6902 (spectrum is G9 IIb)
    III normal giants
        IIIa, Example: ρ Persei (spectrum is M4 IIIa)
        IIIab Example: δ Reticuli (spectrum is M2 IIIab)
        IIIb, Example: Pollux (spectrum is K2 IIIb)
    IV subgiants
        IVa, Example: ε Reticuli (spectrum is K1-2 IVa-III)
        IVb, Example: HR 672 A (spectrum is G0.5 IVb)
    V main sequence stars (dwarfs)
        Va, Example: AD Leonis (spectrum M4Vae)
        Vab[27]
        Vb, Example: 85 Pegasi A (spectrum G5 Vb)
        "Vz", Example: LH10 : 3102 (spectrum O7 Vz), located in the Large Magellanic Cloud.[28]
    VI subdwarfs. Subdwarfs are generally represented with a prescript of sd or esd (extreme subdwarf) in front of the spectra.
        sd, Example: SSSPM J1930-4311 (spectrum sdM7)
        esd, Example: APMPM J0559-2903 (spectrum esdM7)
    VII (uncommon) white dwarfs. White dwarfs are represented with a prescript wD or WD.

[smjjames]

Wouldn't having the diameter twice in there make it confusing?

Also, what about including neutron stars/pulsars? Sure they're on the extreme end of the scale (they aren't even on the HR diagram I don't think), but we should include those sometime.

[Dan Dixon]

There's the new results from today's efforts (see the screenshot below).

I loaded our Solar System, switched to Chart mode, then set the Sun to have a temperature of 10000 K. Since the mass & luminosity were both locked, this shrunk the visible size of our sun.

The checkbox next to luminosity links mass and luminosity (so uncheck it to change the luminosity without changing the mass).

Also, could there be an option to use Fahrenheit?

I've added the converted Fahrenheit value (from Celsius) for planet surface temperature in the hover tip.

These features will be in the next update 2.1.5.

[FiahOwl]

There's the new results from today's efforts (see the screenshot below).

I loaded our Solar System, switched to Chart mode, then set the Sun to have a temperature of 10000 K. Since the mass & luminosity were both locked, this shrunk the size star.

The checkbox next to luminosity links mass and luminosity (so uncheck it to change the luminosity without changing the mass).

Also, could there be an option to use Fahrenheit?

I've added the converted Fahrenheit value (from Celsius) for planet surface temperature in the hover tip.

These features will be in the next update 2.1.5.

Wow, you are pumping updates fast.

[vh]

Making it hotter also turned it blue
intended? or did you have the sun blue previously; anyway, pretty cool. Maybe a slider for "Mass-Luminosity power value"

[Dan Dixon]

Making it hotter also turned it blue
intended? or did you have the sun blue previously; anyway, pretty cool. Maybe a slider for "Mass-Luminosity power value"

Yes. Hot stars are blue. Cool stars are red.
http://www.universetoday.com/24640/color-of-stars/

And the Mass-Luminosity power value will be locked at 3.5 (uncheck to set mass and luminosity on your own). Perhaps in a future version we'll expand this. I don't want to make it too complicated.

[smjjames]

Yea, its getting complex already, but its complex in a good way since we're doing it steps at a time and the whole thing is interlinked anyways.

@mudkipz: Same thing for fire, a cool (relatively) flame is reddish and a hot flame is blue. Stars and fire are both the same state of matter though, which is plasma.

Also, what about temperature, I thought luminosity and temperature were interlinked?

[Dan Dixon]

Also, what about temperature, I thought luminosity and temperature were interlinked?

Luminosity, Temperature, and size (or radius/diameter) are all linked.

A big cool object can have the same luminosity as a small hot object. Make sense?

[smjjames]

I get what you're saying, but I'm not really sure how the whole thing works. I'll just have to play around with the new interlinked values I guess.

[Dan Dixon]

The luminosity of an object is determined by how hot (the temperature) an object is and how big it is.

Two stars of the same temperature, but different sizes will have different luminosities.

Two stars of the same size, but different temperatures, will also have different luminosities.

Perhaps this will help:
http://ceres.hsc.edu/homepages/classes/astronomy/spring99/Mathematics/sec20.html

[smjjames]

The luminosity of an object is determined by how hot (the temperature) an object is and how big it is.

Two stars of the same temperature, but different sizes will have different luminosities.

Two stars of the same size, but different temperatures, will also have different luminosities.

Perhaps this will help:
http://ceres.hsc.edu/homepages/classes/astronomy/spring99/Mathematics/sec20.html

And what determines the temperature of the star? I get the whole concept here though.

[Dan Dixon]

The mass. Very generally... the more massive a star, the higher the temperature.

[smjjames]

Yea I'll just have to play around with the new interlinked values.

[dhm794]

Am I the only one who can't change the Earth's temperature?

[smjjames]

Try moving the Earth further or closer to the sun................

[Dan Dixon]

I should change that so it's clear it's a non-editable value... the textbox for temperature looks editable, but it's not. It's calculated based on the stars temperature, distance, and the planet's albedo and atmosphere emissivity.

[smjjames]

I should change that... the textbox for temperature looks editable, but it's not. It's calculated based on the stars temperature, distance, and the planet's albedo and atmosphere emissivity.

Hrm, if you edit the temperature like you would for anything else, it changes other values connected to it, in this case, distance. So you could set it up that way. Could get complicated by the slider settings though, but I guess you can do it like you did with Luminosity, have a checkbox to lock it so that if you change temp, it doesn't change distance and vice versa.

[Dan Dixon]

Hrm, if you edit the temperature like you would for anything else, it changes other values connected to it, in this case, distance...

This becomes very complicated if you have more than one star (as the 2.1.5 update will also calculate the temperature considering all stars in the simulation).

I don't see much value or reason that this value needs to be editable. You can edit the albedo of the planet and the properties of its atmosphere, isn't that enough?

[smjjames]

Hrm, if you edit the temperature like you would for anything else, it changes other values connected to it, in this case, distance...

This becomes very complicated if you have more than one star (as the 2.1.5 update will also calculate the temperature considering all stars in the simulation).

I don't see much value or reason that this value needs to be editable. You can edit the albedo of the planet and the properties of its atmosphere, isn't that enough?

Yea, it would get much too complicated and I was just musing about it.

[Dan Dixon]

It's a good question: why isn't the value editable? And if it can be made editable, then it should be.

In this case... I think it makes sense that it's the result of other editable parameters.

[FiahOwl]

How about the further the object is away from the sun, it receives less light? (Visually) (and the closer the object is away from the sun, it receives more light?)

[smjjames]

How about the further the object is away from the sun, it receives less light? (Visually) (and the closer the object is away from the sun, it receives more light?)

The atmosphere feature more or less reflects that, temperature wise. However, I've noticed that the light from the star doesn't fade and there is a sudden cutoff at 100 AU (further out than Pluto), so indead of it just being lit lit lit and bam dark dark dark, it would be a gradual fading. In fact, way out where Pluto is, the sun would be barely distinguisable from other stars.

[Dan Dixon]

How about the further the object is away from the sun, it receives less light? (Visually) (and the closer the object is away from the sun, it receives more light?)

Yes... better visually representing what the numbers say (like luminosity) is on the list for the next major update due out in 2012.

[Kevin1994]

still no update for other users