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Questions tagged [radiation]

Questions regarding the emission of high energy particles or waves from astrophysical sources.

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americium 241 gamma source [closed]

the EPA, and Wikipedia state that Americium-241 decays mainly by alpha radiation. But the equation of decay implies that a gamma ray is produced for every alpha particle produced. Is that the case? ...
dkmax's user avatar
  • 21
7 votes
1 answer
2k views

How would radiation pressure inside of the Sun affect an indestructible person?

I went down something of a rabbit hole regarding whether an indestructible person trying to walk on the Sun would fall in, and sink. I want to know how radiation pressure would affect that person. As ...
PhysicsNoob's user avatar
2 votes
1 answer
112 views

The result of my calculation gives too much error, how to solve it?

NOTE: At the end of my post the output is shown as a list of tuples. The first value in each tuple is the result and the second value is the estimated error on that result. Near the end, the estimated ...
Shayu xiao's user avatar
1 vote
0 answers
48 views

Number of neutron stars by radiation band

Since the number of known neutron stars ain't reached yet 4000 at the time of writing, I am wondering about how neutron stars are classified in terms of their radiation spectrum. Clearly, some neutron ...
Jimmy Bionic's user avatar
4 votes
1 answer
104 views

Could the magnetic field of Earth protect life from Jovian radiation if it was a moon of Jupiter?

While the genesis of this question derives from a hypothetical scenario, the question itself (whether Earth's magnetic field is strong enough to withstand Jupiter-strong radiation) isn't, so I hope ...
user177107's user avatar
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4 votes
1 answer
105 views

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
6 votes
1 answer
172 views

On the Radiation Field of large Gas Giants

I am woring on creating a fictional star system, and I need to find an answer to a question to find an accurate way to depict this. I am aware that Gas Giants create a dangerous field of radiation ...
DanceroftheStars's user avatar
3 votes
2 answers
110 views

Could a super Jovian planet have mild radiation belts?

Will a large gas giant always have powerful radiation belts or could a milder radiation environment exist even around super Jovian planets? I know Jupiter’s radiation belts are so strong due to a ...
Elhammo's user avatar
  • 1,107
2 votes
1 answer
178 views

Is life (as we know it) even possible around M-class stars?

My Question is about the fascination in looking for life on M class or Red Dwarf stars. We all know that Most stars (70%) are M Class, so looking at those stars is going to be important. The "...
Thomas Jones's user avatar
0 votes
0 answers
36 views

sun - do gamma rays reach radiative zone

So in the sun's core, gamma rays are produced and right away, in the few milimetters, compton scattering happens. As I understand the compton effect, gamma ray will first collide with free electron, ...
Giorgi Lagidze's user avatar
0 votes
1 answer
103 views

Emitting light from the Sun [closed]

I might be asking too many questions here, but they all seem related to each other and knowing them simultaneously is the only way to understand this subject as I have tried my best googling already. ...
Giorgi Lagidze's user avatar
1 vote
0 answers
26 views

do we observe emission spectrum? [duplicate]

When light generated by the fusion in the sun goes through the layers of the sun and finally reaches outer layers and in the end atmosphere of the sun, we know it goes through hydrogen for example. ...
Matt's user avatar
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5 votes
3 answers
3k views

How can redshifted light be detected?

I've been reading about redshifts and it got me really curious. Basically, I want to figure out how we know light is redshifted and what's the original emitted light. I found the following question ...
Matt's user avatar
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6 votes
1 answer
548 views

What do the symbols signify in Dr. Becky Smethurst's radiation pressure equation for black holes?

In her most recent video, "An ULTRAMASSIVE black hole has been discovered in a BRAND NEW way!", as well as a previous video, "How massive can black holes get?", Dr. Becky Smethurst ...
Kurt Hikes's user avatar
  • 5,097
10 votes
2 answers
1k views

Why does the CMB conform to black-body formula for 2.71 degrees, when it's the stretched emission at a far hotter temp?

Physicist Chad Orzel in "Einstein's Legacy" discusses Planck's Black-Body formula, stating that it fits perfectly to everything we see, from toasters to stars. Fine. Then he says it ...
GulbenkianD's user avatar
6 votes
3 answers
3k views

What is the apparent size of Earth from the Sun?

Heatwaves have been in the news in recent years. I found it amazing to consider that the energy from the Sun is enough to kill you, when only a tiny fraction of its radiation reaches Earth. Then I ...
albertoeda's user avatar
15 votes
7 answers
11k views

How did the Milky Way quasar not disrupt life on Earth?

According to most sources of information I have found (A Quora answer and books), when galaxies become quasars, they destroy all life in their host galaxy, as they output so much radiation that they ...
Alastor's user avatar
  • 2,659
4 votes
0 answers
41 views

M Dwarf radiation and habitability at the terminator of a tidally-locked planet?

I know that M Dwarf stars emit intense solar flares, which is thought to pose a potential problem for the emergence of life on planets that orbit them. But I was wondering if the life that might exist ...
Elhammo's user avatar
  • 1,107
6 votes
0 answers
98 views

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
  • 1,386
2 votes
0 answers
77 views

If Ganymede had a thick, Earth-like atmosphere, would the surface be protected from Jupiter's intense radiation?

Obviously, this is a totally hypothetical, alternate version of Ganymede, since it would also need to have more mass and a stronger intrinsic magnetic field to hold onto a substantial atmosphere. But ...
Elhammo's user avatar
  • 1,107
7 votes
1 answer
227 views

Why does sychrotron radiation only involve relativistic electrons?

I'm reading this chapter of Essential Radio Astronomy. It says that we can divide bremsstrahlung into electric or magnetic breaking radiation, depending on which field is the source of the ...
Loika's user avatar
  • 177
4 votes
2 answers
197 views

Are there areas within Jupiter's magnetosphere without powerful radiation?

I know Jupiter has powerful radiation belts, but I'm wondering if there are places within the magnetosphere that are relatively calm. I'm asking about Jupiter (a gas giant we know) because I'm curious ...
Elhammo's user avatar
  • 1,107
3 votes
0 answers
71 views

What is the density of photon energy in intergalactic space? [duplicate]

What is the average density of photon energy (over all wavelengths) in intergalactic space? In other words, if you took a typical cubic meter of intergalactic space, how much electromagnetic radiation ...
MarkVonTexas's user avatar
5 votes
0 answers
36 views

How to model the kinematics of gases expelled from comets and planetary atmospheres?

Once the ices of comets sublimate, where do they move to, and with which equations do you describe their motion in the interplanetary medium? Similarly, where do the gases that are stripped from the ...
Astrolien's user avatar
  • 151
1 vote
1 answer
310 views

Conservation of specific intensity

I am trying to understand the proof of the conservation of specific intensity. Here we are trying to prove that specific intensity at dσ1 and dσ2 along the ray emitted by a source is the same. I don't ...
radastro's user avatar
  • 115
0 votes
0 answers
116 views

How luminous does a brown dwarf have to be to illuminate an Earth-sized planet with 0.5 lux at 2,000,000 kilometers away?

A brown dwarf is a deuterium-fusing substellar object, and, in the cases of the larger ones, a lithium-fusing one. They often emit electromagnetic radiation in frequencies that humans cannot see. ...
KEY_ABRADE's user avatar
2 votes
1 answer
243 views

Why is synchrotron radiation from relativistic electrons low in energy?

Why do populations of relativistic (high energy) electrons emitting synchrotron radiation emit at mostly radio wavelengths? The fact that they are high energy makes me think they would emit high ...
theta's user avatar
  • 258
1 vote
0 answers
35 views

which fraction of the solar radiation corresponds the blocked part by Venus at its transit upon he sun?

Well, asumming that Venus orbits the Sun at 0.7233 AU and its diameter is 12,104 km, I can conclude that its angular diameter seen from the earth is ~1', then its represents ~1/31 part of the angular ...
Esteban Vera's user avatar
-1 votes
1 answer
557 views

How far away from the sun would I have to be for radiation not to kill me?

If I were freely floating in space within our solar system, and nothing could kill me but radiation from the Sun, what would be the safe distance? I know that Earth´s distance from the Sun would be ...
Jorge Al Najjar's user avatar
1 vote
0 answers
31 views

Evaluating Intensity ratio $I(0,\mu)/I(0,1)$ in non-isotropic region

We are given a problem: Consider a grey atmosphere in radiative equilibrium. If the total pressure ($P$) and energy density ($u$) are related by $$P=\frac{u}{\tau^2}$$ in a non-isotropic region, ...
Young Kindaichi's user avatar
3 votes
1 answer
195 views

Do gamma rays escape from stars when turning into white dwarfs

I'm very curious about this : if the Sun were to become a white dwarf, would Earth get blasted with high-energy electromagnetic radiation? I know that current predictions say that Earth will be ...
Dave's user avatar
  • 31
5 votes
1 answer
97 views

Are there any spectral lines with smaller frequencies than the hydrogen line?

The 21 centimeter hydrogen line originates from the hyperfine transition of neutral hydrogen. Are there any bigger wavelengths that originate from this method? Radio emissions from rotating stellar ...
Evamentality's user avatar
0 votes
1 answer
53 views

Are plasma nuclei detectable? By the occasional emission of gamma rays, perhaps?

As stated above.... How often do nuclei stripped bare emit radiation? Can nuclei be identified by the wavelengths or amplitudes of gamma rays they emit? How about isotopes?
Kurt Hikes's user avatar
  • 5,097
2 votes
1 answer
89 views

How do the stars in the near-infrared (NIR) radiate?

Let's say we are studying the integrated near-infrared (NIR) light of a distant spiral galaxy. We would expect most of this light to be dominated by red giants stars and dwarfs. I assumed these stars ...
Astroturf's user avatar
  • 1,111
5 votes
2 answers
189 views

Directionality of solar flares

I have read a number of articles about Coronal Mass Ejections (CME) and solar flares and I’m trying to establish how directional the radiation from them is. I am aware that radiation from these solar ...
Slarty's user avatar
  • 359
8 votes
1 answer
272 views

The physical processes of emission lines in cosmic nebula

I think I understand how absorption lines in cosmic bodies occur. But after reading about the emission lines in quasars I am wondering more and more about the physical processes causing the emission ...
NeStack's user avatar
  • 313
2 votes
1 answer
547 views

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
  • 71
0 votes
1 answer
415 views

Does Hawking Radiation really exist and Why "negative energy" in virtual particles? [duplicate]

I'm doing some research on black holes for a science video contest - more specifically, on Hawking Radiation. As far as I know, there are these constant quantum fluctuations of "virtual" ...
AdiBak's user avatar
  • 655
11 votes
1 answer
460 views

Can the energy transport by radiation occur in the convection region of a star?

I am new to stellar astrophysics and trying to understand the energy transports in the interior of stars. Can the energy transport by radiation occur in the convection region of a star? Here are my ...
Linda's user avatar
  • 111
6 votes
1 answer
341 views

Why do M dwarfs emit more X-ray radiation than larger, more luminous stars?

I have read that "The relative amount of harmful radiation (to life as we know it) that stars emit can be 80 to 500 times more intense for M dwarfs relative to our Sun". Source This seems ...
Astroturf's user avatar
  • 1,111
3 votes
1 answer
99 views

Why wasn't CHEOPS data taken during passage through the South Atlantic Anomaly downlinked in this case, resulting in gaps in photometry?

Section 4.1.2. CHEOPS in Six transiting planets and a chain of Laplace resonances in TOI-178 says Due to the low-Earth orbit of CHEOPS, the spacecraft-target line of sight was interrupted by Earth ...
uhoh's user avatar
  • 30.5k
1 vote
0 answers
597 views

Background radation on Venus?

Venus is often refered to as Earth-twin, simply because of its similar size. In the very hypothetical case of a human mission to Venus, and leaving the all other challenges of Venus toxic atmosphere ...
B--rian's user avatar
  • 5,616
4 votes
0 answers
80 views

In terms of power delivered to Earth, what is the brightest object in the sky?

I was reading about TXS 0506+056, a distant blazar. The Wikipedia article mentions it is one of the brightest objects in the sky at both gamma and radio frequencies. This got me wondering — if we ...
Riley Scott Jacob's user avatar
2 votes
0 answers
143 views

How is solar radiation pressure included in the SGP4 orbital propagator?

TLE sets serve as input elements for the SGP4 orbital propagator. Several orbital perturbation effects are considered in the SGP4. However, it is not obvious to me how (or if) the solar radiation ...
fl0ta'''s user avatar
  • 43
19 votes
2 answers
1k views

Problem regarding the absorption lines of the Sun

Some of the wavelengths of light that are emitted from the Sun will be absorbed by atoms in the outer layer of the Sun and also the atmosphere of the Sun, and we see this as absorption lines in the ...
User3141's user avatar
  • 319
3 votes
2 answers
76 views

Distinction between signal from terrestrial and signals from celestial sources

How is it confirmed that a radiation source (not in visible light) is either terrestrial or celestial? If in-depth explanation and/or references are possible, I would be grateful.
user30981's user avatar
  • 199
4 votes
1 answer
528 views

How much solar UV radiation would someone get who were on the surface of Titan?

The Saturn system is about 10 times as far from the Sun as the Earth. This question is concerning Titan for two reasons: Titan has an Earthlike atmosphere so you don't have to account for a higher ...
Ioannes's user avatar
  • 1,090
4 votes
2 answers
441 views

Is there a connection between the solar wind and the cosmic radiation?

Cosmic radiation consists of high-energetic particles, mostly protons, that come amongst others from supernovae and our sun, right? The solar wind also consists of charged particles, like protons and ...
Mike's user avatar
  • 43
0 votes
0 answers
45 views

Transition of Domination in the Universe

While deriving the epoch of matter-radiation equality, we assume the transition from radiation dominated universe to matter dominated universe as instantaneous. But how instantaneous is this ...
Arnab Chowdhury's user avatar
3 votes
2 answers
1k views

Why does radiation not need a medium to travel?

I wanted to know how radiation moves in vacuum of space and why it doesn't need any medium ? ( Like sunlight reaching a planet )
Deoxzy's user avatar
  • 49