Questions tagged [temperature]

Temperature is a measurement of the average kinetic energy of the molecules in an object or system. In simpler words: it's the degree or intensity of heat present in a substance or object that is commonly measured with a thermometer.

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Wien's law gives two different results?

Say I have a star with radius $R$ and luminosity $L$. I want to find the frequency of its peak emission. Taking the star as a perfect blackbody, we can use Stefan-Boltzman to see that $$L = 4\pi R^2\...
Captain Chicky's user avatar
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How did the temperature of the solar system evolve?

As a child, I've read that stars ignite during a so-called "nuclear flash". I understood this as a very violent outburst of energy from the sun, causing all dust between the protoplanets to ...
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Is there a formula for calculating surface temperature of a rocky world based on atmosphere and solar input?

For example, a thicker atmosphere would probably lead to less temperature variation . . . I assume that much is obvious. And, greenhouse gases trap heat. But when posed with a question like "...
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When did Venus get as hot as it is now?

My previous question turned out to not ask the question I thought I was asking. I have read that Venus began its heating-up around 700-750 million years ago. When did the Venusian atmosphere get ...
Michael Bonnet's user avatar
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When did Venus reach approximate radiation equilibrium?

I have read that Venus is roughly at radiation equilibrium - that is, heat out is approximately equal to heat in. I have also read that Venus began its heating-up around 700-750 million years ago. My ...
Michael Bonnet's user avatar
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On a theoretical young tidally locked planet and its relationship with temperature

I have a question regarding tidally locked planets, regarding the length it takes to reach a certain temperature. How would one calculate the estimated temperature after a certain amount of time being ...
DanceroftheStars's user avatar
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Public data for calculating equilibrium temperature of exoplanets

I am a high school student beginning a simple independent project to calculate the equilibrium temperature of exoplanets. I'm curious to see how many exoplanets have a similar equilibrium temperature ...
HSStudent's user avatar
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Is the Sun hotter today, in terms of absolute temperature (i.e., NOT total luminosity), than it was in the distant past?

I am constantly reading that the Sun is at least 20% 'hotter', in terms of total radiation/luminosity, than it was a few million years after its formation (i.e., after the Hayashi stage...) But what ...
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the sun - relationship between gravity and temperature

In the sun's core, we know it's very hot. I was curious to research why it was exactly and I think 99% of answers are not fully correct. They say that it's because of nuclear fusions. I'd not agree as ...
Giorgi Lagidze's user avatar
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How to calculate the day/permanently dark/night temperatures of different surfaces for exoplanets?

I am trying to calculate the different temperatures (day, night, permanent day/night for tidally locked planets) for different surfaces of exoplanets like land, water, gas, ice. I am using an ...
VirtualPaul's user avatar
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Goldilocks Zone Temperature Range for Habitation

Is there a generally accepted Kelvin temperature range for exoplanets habitable zone. So for example, I can look at for example, http://exoplanet.eu/catalog/toi-2134_b/ and say the planet is in the ...
MiscellaneousUser's user avatar
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Temperature of a gas giant 23 AU from Fomalhaut

If a gas giant, weighing about 30 Jupiter masses, orbited the A-type star Fomalhaut at 23 AU, what would its temperature be? Would it be warm enough to have ammonia clouds like Jupiter or Saturn, or ...
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Is the solar system barycenter affecting the Earth weather?

I do not have the numbers but I guess the solar system barycenter should move much more than the Earth radius, and if that is correct then it should not be affecting the Earth's temperature. I mean, ...
Enrique's user avatar
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Which star has a higher effective temperature, a red dwarf or a red giant?

According to the Hertzsprung-Russell diagram, they would roughly have the same temperature, but I've read in bibliography that the surface temperature of the red giant is about 5000K and the one of ...
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How hot would the core of the Red Giant Sun be?

After the Sun becomes a red giant, it will heat up its core to 100 million kelvins, which initiates the Triple-Alpha fusion process, which heats up the star's core even further and cause it to undergo ...
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Cooling timescale for an interstellar dust grain

I would like to estimate the cooling timescale for an interstellar dust grain, starting at 200K, down to 100 K. The equation I have come up with is: $\displaystyle t_{cooling} = \frac{mC\Delta T}{Q_{...
lucas's user avatar
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Reason for different surface temperatures of Tau Ceti and Epsilon Indi at similar properties

While looking at a list of nearby stars, I noticed that the spectral classes were not always consistent compared to the masses (and radii) of the main sequence stars. Especially the comparison between ...
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Explanation for Planck 2018 temperature fluctuations strongest peaks

As it can be seen from Plank 2018 Cosmic Microwave Background temperature fluctuations data- There are 3 sharp peaks at multipole expansions $\ell \approx 250, 550, 800 $. Also as multipole expansion ...
Agnius Vasiliauskas's user avatar
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Extract surface density profile from a temperature profile?

I have a protoplanetary disk model which outputs a temperature vs. radius profile, based on radiative transfer. Looks something like this... One of the inputs to the model is the surface density ...
lucas's user avatar
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Is there a simple way to get $T_{\mathit{eff}}$ estimates for Gaia EDR3?

For just hobbyist purposes (3D starmap) - I'm trying to infer temperature from EDR3 data to make a rough assessment of stellar type. I tried applying figure 2 from this doc: https://arxiv.org/pdf/1008....
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Pressure and chemical potential of quantum Schwarzschild black hole

Just as Stephen Hawking showed that even Schwarzschild black holes have a temperature, shouldn't it also have a pressure and chemical potential? Are there any analytical formulae of those as well as $$...
riemannium's user avatar
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Why does the factor of $\frac{1}{4}$ appear in this equation?

This is an equation my professor wrote to calculate the equilibrium surface temperature of a planet:$\frac{S}{4}(1-A) = \sigma T^4$. (A is the albedo of the planet and S is the intensity of starlight ...
Ambica Govind's user avatar
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How to estimate the temperature of an interplanetary dust grain?

I'm trying to solve this task: Estimate the equilibrium temperature of an interplanetary spherical dust grain if it is located at a distance of 3 AU. from the Sun, and the substance of the dust ...
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color of stars and temperature

I recently got questioned on why stars are the color they are. I know the color of a star depends on its surface temperature where hotter stars produce more light towards the blue side of the spectrum ...
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Star and Planet temperature relationship

Let's assume there is this planet with no atmosphere, no geothermal activity and an average temperature $\ T_p$. Now, if the distance between the planet and the star is $\ d$ and the radius of the ...
Lorenzo Boole's user avatar
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Is it possible for a planet to heat up its moon to habitable temperatures solely through infrared radiation?

Stars are powered by nuclear fusion and the energy released radiates through their surface as heat. But all objects radiate away some form of electromagnetic radiation depending on their temperature. ...
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How can a 1-pixel image of a rotating asteroid be used to measure its thermal inertia?

Phys.org's Observatory in Chile takes highest-resolution measurements of asteroid surface temperatures ever obtained from earth discusses imaging of millimeter wave imaging of the surface of asteroid ...
uhoh's user avatar
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If the sun would be two times as big and with the same power output would temperature on Earth change? [duplicate]

Suppose the suns radius is increased by two. And suppose its emitted power doesn't change. Will we notice this on Earth? It will seem twice as big but apart from that what will we notice(if anything). ...
Deschele Schilder's user avatar
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When thermal infrared space telescopes spot asteroids, are they seeing the body's own thermal emission, or reflected TIR from the Sun?

From the Space SE question Why has the Earth-Sun libration point L1 been chosen over L2 for NEOCam to detect new NEOs?: above: Profoundly not-to-scale illustration of NEOCam in an orbit around the ...
uhoh's user avatar
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At high temperatures, do planets glow like blackbodies?

I've been messing around in Universe Sandbox for a while and noticed that as a planet heats up, it glows like a blackbody starting at ~4000 K. Is the simulation here accurate, or do very hot planets ...
WarpPrime's user avatar
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How can there only be "11 phonons" in the mirrors of LIGO interferometers?

LIGO is an incredibly sensitive detector of small changes in space due to the passing of gravitational waves and uses some very high-level mathematics and physics and experimental techniques to drive ...
uhoh's user avatar
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Why red giants have cooler surface than MS stars?

I know that with increasing age and depletion of hydrogen in the core the radiation inside a main sequence (MS) star increases pushing the envelope/surface of the star outwards. What I don't ...
NeStack's user avatar
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Could a heavy exoplanet squeeze water into being liquid and 4° warm?

Let's say there is an exoplanet orbiting its host star well outside its habitable zone. Suppose further that it has a lot of water, being perhaps comparable to earth when it comes to the volume ratio ...
AlgebraicsAnonymous's user avatar
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2 answers
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How close to a host star can a tidally locked planet be and its dark side still maintain a moderate temperature?

So, imagine an atmosphere-less planet, tidally locked to a sun-like star. How close to the star can the planet be before its dark side becomes too hot? I imagine that at some point the rocks on its ...
Anixx's user avatar
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Given that a color index ($B-V$) of star A is lower than that of Star B, What can we say about the stars?

The color index $B-V$ of the star is defined as $$B-V\equiv M_B-M_V$$ Let us suppose it's given $$(B-V)^{(A)}<(B-V)^{(B)}\Rightarrow M_B^A-M_V^A>M^B_B-M^B_V$$ The notations are a bit confusing, ...
Young Kindaichi's user avatar
2 votes
1 answer
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What is the Milne-Eddington Approximation?

In this paper: Planet temperatures with surface cooling parameterized it states in the "radiation model" the following: The Eddington–Milne approximation relates $T_0$ and $T_e$ through the ...
Astavie's user avatar
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Stellar temperature ~ frequency relationship?

According to Wikipedia, 76% of all stars are of spectral type M, 12% are of K, 7.5% are of G, etc. (see this section on Stellar Classification). This is very helpful, but is too vague, as the ...
WarpPrime's user avatar
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8 votes
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What is the history of the average pressure, density, and temperature of the matter in the universe over time?

This question is inspired by this more specific question where Cerelic wanted to know if conditions were suitable for liquid water to exist during an epoch when the characteristic temperature of the ...
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30 votes
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Could liquid water have existed in open space 15 million years after the Big Bang?

Around 15 million years after the Big Bang, the ambient temperatures was about $24^\circ {\rm C}$, which is in a range where water could be liquid. Could liquid blobs of water be existent then? PS: I ...
Cerelic's user avatar
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2 votes
2 answers
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Why temperature of dark side of moon is not 3 Kelvin

The temperature of the space between Earth and the Moon is around 3 Kelvin ($\approx -270^\circ {\rm C}$). The moon has no atmosphere, therefore the heat convection is not possible from the bright ...
Ganesh Kulkarni's user avatar
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2 answers
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How would the temperature on earth be if the sun was slightly more or less powerful?

The temperature on earth is around 14C celsius. It is around 1370 W/m^2 from our sun. The earth has an albedo of around 0.3 On Tatooine (from Star Wars) i have been able to calculate it goes from 1066 ...
Bob the Turtle's user avatar
2 votes
2 answers
179 views

How to accurately measure the temperature of red supergiants?

I just (February 28th, 2021) heard the news on progress how to measure the temperature of super giants: Red supergiants are a class of star that end their lives in supernova explosions. Their ...
B--rian's user avatar
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Why do degenerate objects get hotter as more mass is added?

After reading this question, I decided to post a question about degeneracy. I've seen simulations on large, $15\text{+ }M_J$ objects that are accreting mass. They do not grow in radius, instead they ...
slowerthanstopped's user avatar
1 vote
1 answer
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How do you refer to comparative temperature?

Earth's average surface temperature is about 288 K. If we had a hypothetical exoplanet with a surface temperature of 300 K, this would be about 4% higher than Earth's. Because we say Earth radii and ...
Xi-K's user avatar
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What factors influence a star's temperature and density?

Assuming a relatively even proportion of mass and radius, a 0.25 solar mass and radius star would have a density of 22.5003 g/cm³, or about 16 times our Sun's density. However, there is obviously a ...
Xi-K's user avatar
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3 votes
1 answer
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How can I estimate how long will a main sequence star stay on the main sequence given its temperature?

I have a generic zero-age main sequence star. The only thing I know about it is its temperature. How can I estimate time time it spends on the main sequence (in millions of years)? I've seen equations ...
slowerthanstopped's user avatar
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Equilibrium Temperature for Extremely Cold Planets: Incorporating the CMB and Intrinsic Radiation

I want to check if I'm doing this right. I'm computing the equilibrium temperature for planets where the CMB and/or the planet's intrinsic radiation (as in weakly radiating jovians) matters. I start ...
MackTuesday's user avatar
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1 answer
166 views

Exactly how long does it take for the exposed core of a star to cool from its starting temperature (several billion K) to ~50,000 K?

OK, I didn't know how I should word this question. But the basic point is that most white dwarfs that we have classified fall in temperature ranges from ~50,000 K to 6000 K. However, at the end of a ...
WarpPrime's user avatar
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3 votes
1 answer
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What would the Earth's peri- and aphelion have to be in order to have the same seasons due to its orbit?

Imagine the Earth had no axial tilt but had seasons due to a very elliptical orbit. How elliptical would the Earth's orbit have to be in order to have about the same seasons as it has now (just with ...
Greenhorn's user avatar
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Is every single large solid body orbiting entirely outside of the frost line covered in ice?

Not sure where I heard that but I want to make sure if it's true. Forget about the asteroid belt for a minute: Are all the moons of the outer planets and kuiper belt objects covered in water ice?
standbsck's user avatar