# 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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### What does it specifically mean that internal energy is a function of temperature and volume U(T,V)? [closed]

We know that internal energy is a function of temperature and volume U(T,V ) . I wanna know specifically that what type of function is it , or more clearly , type of inverse or direct relation ? In ...
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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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### Blackbody curve in RGB for objects less than 1500 K?

We know the colors of stars that have a temperature greater than 1000-1500 K, shown here. However, I am wondering about those stars/brown dwarfs with surface temperatures of less than 1500 K. Is there ...
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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 ...
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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 ...
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### How massive can a cold solid object be?

I understand that a neutron star is dense enough that adding more matter will increase the amount of degenerate matter directly, and the limit to its size is about 1.4 solar masses. But if an object ...
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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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### Why is our Sun hotter than UY Scuti?

As Wikipedia says the surface temperature of UY Scuti is 3,365 K and the sun is 5,778 K Why is the Sun hotter than a supergiant star like UY Scuti?
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### Why doesn't the equipartition theorem disallow spinning dust?

This excellent answer to the question What is the physics of the “spinning dust” contribution to Cosmic Microwave Background measurements? Is well sourced. The abstract of one of the papers there, ...
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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 ...
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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 ...
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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 ...
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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). ...
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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 ...
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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 ...
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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 ...
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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 ...
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### Why is VX Sagittarii classified as spectral type M4-M10?

The largest and most luminous asymptotic-giant branch (AGB) star is VX Sagittarii. Wikipedia states that its spectral type is M4eIa-M10eIa (citing https://arxiv.org/pdf/astro-ph/0608438.pdf which in ...
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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 ...
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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, ...
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### Estimating a star's radius, temperature, and luminosity based on its mass

(See updated figure and description below.) I've been trying to generate ballpark estimates for the radius, temperature and luminosity of stars in the main sequence based solely on their masses (...
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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 ...
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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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### 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 ...
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### Why is the Boomerang Nebula colder than the CMB?

An earlier answer on temperature mentioned that the temp of the Cosmic Microwave Background (CMB) is $2.4\,{\rm K}$ and the temp of the Boomerang nebula as ${\rm 1\,K}$. How did the nebula cool faster ...
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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 ...
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### Why would the Chang'e-4 lander find lunar far side temp. "colder than scientists expected", when the LRO has already been taking thermal readings?

In January, the Chinese probe lander Chang'e-4 was was announced to have found temperatures dipping lower on the far side than expected ("Chinese rover finds lunar nights 'colder than expected'" by R. ...
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### How does Io's atmosphere behave locally near volcanic plumes?

Io's surface air pressure is about $0.3 {\rm mPa}$ but Io's atmosphere is strongly variable, depending on whether it's on the near side or far side of Io (relative to Jupiter) and it collapses at ...
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### 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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### How was the core temperature of the Sun estimated?

It was estimated that the heat inside the core of the Sun inside around 15 000 000 °C - this value is extremely enormous. How did scientists estimate this value?
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### How do stellar temperatures vary?

The temperature of the surface of the Sun (photosphere) is between 4500° - 6000° Kelvin. Inside the core, it's around 15.7 million degrees Kelvin. In other types of stars (neutron stars, white ...
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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 ...
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### 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 ...
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### What spectral type of star has an absolute magnitude of exactly 0?

We know that Vega is the star that serves as the zero point for the UBV color scale, and has an apparent magnitude of nearly zero (+0.02). But its absolute magnitude is +0.58, making it rather far ...
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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 ...
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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?
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### Why can't neutron stars ignite and explode?

Beyond the Chandrasekhar limit, white dwarfs become extremely hot. As a result, previously unfusable carbon can become fusable, causing nuclear reactions. This leads to a thermal runaway and ...
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### What is the coolest white dwarf known?

Okay, so in this ArXiv report from 2014, scientists discovered the coolest white dwarf, with a temperature of below 3000 K. However, as this report was from over 6 years ago, I think this information ...
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### What units are used for the Stefan-Boltzmann law?

I have a star with given temperature in Kelvin and radius in solar radii. I tried to calculate the luminosity of the star using Stefan Boltzmann's law, and got an absurd number (over 1 million). What ...
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### What's the temperature of Pluto's core?

The surface is freezing-nitrogen cold, but it's typical for the temperature to increase towards the core. What's the temperature of the core of Pluto? Is the planet icy and rocky all the way through? ...
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### What is the RGB curve for blackbodies?

I created a program to convert the temperature (in Kelvin) of a blackbody to RGB color. However, it is slightly inaccurate, and the deviations increase for values greater than 10000K and less than ...
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### Can red dwarf stars have a spectral type of L?

We have the "normal" main sequence stars, OBAFGKM. Below K and M are the brown dwarfs, L,T, and Y. Zooming into the area at the edges of M and L, we have spectral types M9, M9.5, L0, and L1. ...
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### Is there an O1 or O0 star?

Okay, we've seen the super hot Wolf-Rayet stars, especially WR 102 and 142, and the "slash stars," many of which are early O (O2-4.5/WN). We know the temperatures of these Wolf Rayet stars. ...