Questions tagged [astrophysics]

Questions involving the physics of the universe, especially the nature of astronomical objects, energy fields, and/or regions, rather than their positions or motions in space.

Filter by
Sorted by
Tagged with
3
votes
1answer
34 views

Non-thermal Sunyaev-Zel'dovich effect

Exactly what is the non-thermal Sunyaev-Zel'dovich effect? From what I understand from reading several papers by Mark Birkinshaw and Sergio Colafrancesco, I get the rough idea that the non-thermal SZ ...
3
votes
3answers
42 views

Does coronal mass ejection include radiation at optical wavelengths?

It is known that during Solar/Stellar Flare, plasma from the corona of the star is released into the space, and travels comparatively slowly. In an hypothetical situation, does the coronal mass also ...
2
votes
2answers
101 views

Why does the Sun show different colour at midday and at morning?

As we see every day in the morning the sun shows a red-orange colour but at midday has a blue-white like colour why? Is it concerned with the distance from the earth or about intensity? How do you ...
1
vote
1answer
93 views

Did universe have finite hydrogen

According to this video stars at end of time and many others on fate of universe they all agree on one thing that stars will eventually convert all the hydrogen into heavier elements and eventually ...
1
vote
3answers
136 views

What orbit is the smallest or takes the least time to complete?

What orbit in our solar system would take the least time to perform 1 orbit? What is the fastest possible orbit to complete in the universe?
5
votes
3answers
130 views

Can't pulsars and stars be used for gravitational wave measurement?

Suppose that we collected photons from a distant star, and they arrive regularly at 15 photons every microsecond onto a CCD, when a gravity wave bends space time, wouldn't the regular 15 photons graph ...
1
vote
0answers
27 views

What could be observed with LOFAR in 230 MHz - 10.0 MHz wavelength?

Nuclear astrophysics greatly interests me and i was wondering if there is something that could be observed with the LOFAR project in this wavelength that would benefit the field? Also some general ...
-2
votes
1answer
97 views

Can the Sun pull an iron asteriods in it's orbit into it? [closed]

Can our Sun's magnetic field strengthen in any way in a short period? Can the Sun pull anything trapped in close orbit around it? What would happen if an object in orbit passes over a sunspot for ...
1
vote
1answer
25 views

Vertical speed vector at which the sun travels to and from the galactic equator

What is the speed of progression of the sun toward and away from the galactic equator during its orbit?
1
vote
1answer
62 views

Is there any positive N on which it's agreed among astronomers that 10^-N is accepted as 0 (zero)? [closed]

Is there any positive N on which it's agreed among astronomers that 10^-N is accepted as, or treated as 0 (zero)? I think one of the sciences that most precision is required is astrophysics. I'm ...
1
vote
2answers
193 views

What is the solar system orientation to its direction of travel? [closed]

I saw the picture and seem incorrectly drawn. Its shows the the edge of the solar system leading facing the Heliosheath. It would not be like NASA to post something as incorrect as this. The solar ...
1
vote
0answers
21 views

Modeling Malmquist Bias [closed]

I am studying astrophysics on the side and came across this problem in the textbook: I am not quite sure how to approach it but I do know I need to account for the Malmquist bias to account for the ...
1
vote
1answer
97 views

When a rogue brown dwarf star hits a white dwarf star, will the collision at most cause a nova? [closed]

When a rogue brown dwarf star hits a white dwarf star, will the collision at most cause a nova? Or can the explosion be heavier?
2
votes
3answers
174 views

Is space a thing? [closed]

Based on my extent of knowledge relating to astrophysics, I once thought space is a thing, which can be twisted a long side with Time regarding masses of objects(According to relativity theory). But ...
2
votes
3answers
171 views

Do interstellar asteroids decelerate and eventually stop?

I do wonder, do interstellar asteroids eventually stop at one point in space after they gradually decelerate (or) even do they decelerate? Though there is no air like on earth and thus asteroids ...
0
votes
1answer
91 views

Are galaxies moving in each direction with same speed?

All galaxies are moving away from each other (us) because of the expansion of the universe. Are they moving with same speed in each direction?
1
vote
1answer
117 views

Mass of the universe

How do we calculate the mass of the universe taking into consideration dark matter? Mass of visible matter can be computed by stellar method, but how do we calculate mass of dark matter which we don'...
0
votes
1answer
32 views

Finding the diameter of a molecular cloud using period of intensity variation of hydroxyl maser

So I have this problem (which I translated to English as accurately as could): When studying a compact molecular cloud with radiotelescope, at a wavelength of 18 cm, hydroxyl (OH) maser(ic) ...
4
votes
2answers
113 views

nonagesimal in Kepler's parallax computation

I'm starting to learn Kepler's Astronomia Nova using William Donahue's translation . In the translator's introduction, it is demonstrated how Kepler did his parallax computation. I failed to ...
4
votes
1answer
114 views

Necessary steps to calculate photon's path by using null geodesic equation

Can anyone please give me an explanation on how to calculate photon's path by using the null geodesic equation? N.B. I know all of the non-zero values of Christoffel symbols.
5
votes
1answer
470 views

Is our universe stable or metastable?

I've been reading and thinking about this subject for some time, but I can't seem to find a clear answer. After reading Q14: Aspects of the Higgs boson suggest that our Universe is only “...
6
votes
3answers
173 views

Universe isn't infinite theory

Forgive me if any of my terminology is off I am no physicist but I have wondered about this question for a while. I have read in various books that if the universe was infinite, and uniformly created ...
0
votes
1answer
55 views

Is the structure of crystalized white dwarf related to nuclear pasta?

There is news of an analysis of a large number of nearby white dwarfs revealing a "pile-up" at a certain point in their cooling which has been predicted to happen due to a phase change where nuclear ...
0
votes
1answer
767 views

Why are blue stars the hottest? [duplicate]

I know that blue stars are the hottest and youngest (according to Universe Today). But what makes them blue, instead of other colors like purple?
4
votes
0answers
47 views

Strength of core-envelope coupling in stars

For a star with a given Zero-Age Main Sequence (ZAMS) mass, as a function of metallicity how strongly is the star's core coupled to its envelope? I understand that the core-envelope boundary is only (...
2
votes
0answers
144 views

Any ideas for an astronomy + ML project? [closed]

I wish to do an astronomy related project which incorporates machine learning.Do you have any suggestions?
4
votes
1answer
62 views

Largest non-hot gas giants

Excluding 'fluffy' or 'puffy' gas giants that are 'inflated by heat from their stars, what is the maximum radius of a gas giant planet. I keep reading things like "...Jupiter is 'about' as big as ...
4
votes
1answer
251 views

Warm jupiter vs hot jupiter, fluffyness

If Jupiter was orbiting at 1AU, replacing Earth, but everything else in the solar system remained as it is currently, how much would the increased heat from the sun increase Jupiter's radius? In ...
4
votes
1answer
79 views

What experiment does this “Tracing the History of Starlight” video try to explain?

The YouTube video Tracing the History of Starlight with NASA's Fermi Mission describes observation by the Fermi gamma ray telescope of EBL (extragalactic background light) gamma rays from 2,000 ...
1
vote
0answers
75 views

How to convert Log(g) vs T_eff to y vs (v-y)?

I have a plot in Log(g) vs T_eff coordinates from my stellar evolution model. The parameters of the model are M=0.8 M_solar, [Fe/H]=-1.19, Y=0.245. I want to convert it to the y vs (v-y) coordinates (...
0
votes
2answers
304 views

Calculating the sun’s position in ECI

I’m trying to calculate visible ISS passes and I need to calculate if the ISS is behind the earth by “drawing” a line between the ISS and the sun and seeing if it crosses earth. I have the ECI ...
2
votes
1answer
72 views

Distance to objects

When we read that, for instance, M31 is 2.54 ± 0.11 Mly (778 ± 33 kpc) away from us, does this distance estimate take into account the travel time of the light we observe? In other words, what is the "...
0
votes
1answer
65 views

Has “GHz-spinning dust” ever been demonstrated in the laboratory?

This excellent answer to the question What is the physics of the “spinning dust” contribution to Cosmic Microwave Background measurements? includes the figure below which helps show what it was the ...
3
votes
2answers
171 views

How would humans with appropriate equipment navigate the surface of Saturn's moon Titan on foot? [closed]

Taking into account the physical characteristics of Titan (e.g. surface gravity, atmospheric pressure), what would be the most efficient method of motion for an astronaut to navigate the surface of ...
3
votes
0answers
144 views

Total number density of galaxies and problematic expression in practise

This post comes from physics exchange forum, I have transfered it here, maybe I will be luckier since I have not received answers on the other forum. Here is the issue : I am asked to give the ...
1
vote
2answers
86 views

How to find the radius of a satellite not knowing the mass

If I know the semi-major axis, the density of the planet, and orbital period.. how can I find the radius of the satellite? I can't think of any formula to use.
2
votes
1answer
63 views

What is the apparent magnitude of the weakest stars we can see in one telescope on the ground with a diameter of 2.4m? [duplicate]

All I know is its main mirror diameter; 2.40 m I also know that the eye, which its pupil is 5mm in diameter can see up to an apparent magnitude of 6. How can I calculate the apparent magnitude that ...
5
votes
1answer
677 views

How does gravity affect pressure under water?

How different would being under water in Europa differ from being under water on Earth? Would it be possible to dive deeper on Europa with a submarine than on Earth and by how much?
3
votes
2answers
473 views

What liquids can be found in the void space?

Is there any material natural or otherwise a free floating liquid that can exist in space? https://space.stackexchange.com/questions/32274/what-liquids-last-the-longest-in-space
3
votes
2answers
227 views

What is the minimum size to be a natural satellite?

Would a smaller satellite be more stable around a smaller planet where the same satellite would not be stable or last around a larger planet? I added the picture to show how moon size planets can ...
-1
votes
1answer
103 views

How long will a ball of ice stay in orbit around Earth? [closed]

How big would a ball of frozen water need to be to last one orbit? How would atmospheric drag effect the ball of water? https://space.stackexchange.com/questions/32188/what-is-the-darkest-orbit-...
2
votes
2answers
119 views

How much of the Universe is subatomic? [closed]

How much does subatomic particles such as photons, tachyons, and electron being the biggest particles etc. occupy space? If put in a ball how big of a ball would that be?
8
votes
1answer
159 views

Estimates for “undetectable” planets in extra-solar systems

As far as I've been able to determine, it appears there are some significant limitations on our ability to detect exo-planets that are below certain sizes or beyond certain distances from their stars....
1
vote
1answer
124 views

What is the reason for magnetic braking?

What is the reason of Magnetic Braking in contact binary stars? Just dark spots? I mean hot spots can have this effect on binaries.
1
vote
0answers
50 views

A high-temperature isolated neutron star could be super-Eddington?

If the surface temperature of a young neutron star is hot enough, say, several KeV, its blackbody radiation could be super-Eddington? Did any paper discuss this scenario before?
7
votes
2answers
201 views

What was the length of the solar day 73 million years ago?

How could this be estimated, or how accurately could it be extrapolated from a present-day measurement of the Earth's spin-down rate?
1
vote
2answers
84 views

Is there a limit to how fast spacetime can bend/warp around an accelerating object?

If in the future a spaceship can accelerate to nearly the speed of light, will it encounter any kind of resistance/drag from the spacetime in front of it not being able to bend/warp fast enough around ...
0
votes
3answers
70 views

Hypothetically, if our sun was yellow would we still see “white” colours?

Hypothetically,if our sun was yellow would we still be able to see white colour on objects like snow,cotton etc.? Would we have the phenomenon of rainbow?
1
vote
1answer
83 views

Does time dilation increase within overlapping gravitational fields?

If a spaceship was to travel to the barycenter of a binary star (the stars having identical size and mass) and come to a stop there, would the people on board this spaceship find that time is moving ...
3
votes
1answer
117 views

Why does the adiabatic exponent decrease at the ionization zones?

The context is the ionization zones in stellar atmospheres or interiors, the Sun, for instance. The adiabatic exponent is the heat capacity ratio: $$\gamma = \frac{c_P}{c_V} = \frac{C_P}{C_V}$$ And,...