# 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.

296 questions
Filter by
Sorted by
Tagged with
29 views

### Does nucleosynthesis happen near a black hole or during its formation?

During its lifetime, a star can synthesize elements to iron because of the pressure and temperature. A neutron star is composed of iron nuclei 56 and up to krypton 118. According to that, a black ...
11 views

### Fermi-LAT gamma ray spectrum too high

I am extracting gamma ray spectrum from Fermi-LAT data. My spectrum is a lot higher than the ones on previous studies of the same object. What could cause a spectrum to go too high?
50 views

### Any good books to read for complete beginners? [on hold]

Currently, I am a Ph.D. student(mathematics) but always loved the field of astronomy hence I would like to read something on the "side" in this field along with my work. So is there any good ...
15 views

### How to convert magnitude to spectral luminosity? [duplicate]

In the Gaia catalogue I have the magnitude of several stars in the G band. I also have the distances to these stars (parallax is known). Additionally, I oftentimes have the effective temperature in ...
31 views

### Cosmology : Formula for the bias of galaxies

first I have posted originally on the physics stackexchange but I have not had answers about my question, so I try my luck on this specific forum (if forums leaders want to delete the original post on ...
162 views

### What is the time dilation less a magnetic field?

Does time dilation drop off like a gravity or does resemble a magnetic field model? Could a smaller body with a magnetic field have more time dilation then a larger body without and to what degree?
101 views

### How to deal with data that's billions of years old?

We look at galaxies that are billions of light years distant and draw conclusions based on the red shift of the light. How is the age of the light accounted for. We see the reality of a galaxy perhaps ...
98 views

### Book recommendation

I'm looking for a modern astrophysics text. I've had Barbara Ryden's book Foundations of Astrophysics recommended to me and it sounds okay, but the only review of it I've seen slagged off the problem ...
94 views

### If space is negative energy and matter is positive energy then does that mean the universe is finite?

I was reading a book by Stephen Hawking, it was written that universe is made up of 2 ingredients,i.e., space and energy and space was the negative energy, so they add up to 0. But since space is ...
11k views

### Why can't we feel the Earth's revolution?

I googled it and checked a few Q&A and there's only things about "Earth's rotation". But why can't we feel the revolution? They say we can't feel the rotation because the Earth spins at a ...
69 views

### Three Body Problem

I tried to solve the three body problem numerically. While after 1000 time steps the system looks stable (See Fig.1) it is completely unstable after 10000 time steps (See Fig.2). Is that an intrinsic ...
41 views

### How to write a normalized, dimensionless form of Binet's relativistic equation?

$$\frac{\delta^2 u}{\delta \theta^2} + u = \frac{\mu}{h^2} + 3 \mu u^2$$ This is Binet's relativistic equation. Here $u = 1/r$ where $r$ is the radial distance, and $\mu$ is the reduced mass of the ...
35 views

### To show perihelion precession motion of Mercury in Python with matplotlib

I'm trying to make it more general code so I can trace even a parabola or hyperbola for $e=1, E=0$ and $e>1, E>0$ respectively. And after achieving that general code I want to make the same code ...
104 views

### Can I learn astrophysics and astronomy with my basic math?

I want to learn astrophysics and astronomy, I'm very interested in it because there are many questions that popped up in my head, and really curious about things, but I'm afraid of a little bit on ...
48 views

### Given a star's mass, age, and composition, how do I calculate the rest of its properties?

If I'm given a star's starting mass, starting composition (metallicity), and its current age, How do I calculate the star's luminosity, current mass, and radius? I want to know how to do this for any ...
66 views

### Why are Bok globules so cold?

I have recently read a bit a out Bok globules. One thing, that is repeatedly emphasised is that they are among the coldest objects in space, with a temperature of ~3 K. Why is that so? Naively, I ...
32 views

### Astrophysics of Supernovae - Energy over Distance?

I need this for worldbuilding, but it is a physics question. I want to be able calculate the energy over distance from a hypernova of a variable star like Eta Carinae. Understanding what energy levels ...
22 views

### How is “surface brightness dimming” derived from redshift in the NED extragalactic database

I have several questions regarding “Surface Brightness Dimming” in the “Quantities Derived from Redshift” section of the Nasa/ipac Extragalactic Database. As an example, please use quasar IRAS F08279+...
71 views

### Law of Conservation of Information?

I read about Hawking and Leonard Susskind and their debates about whether information is destroyed or not if it falls into a black hole. It was resolved in favor of information always being conserved,...
12 views

### How to convert the observed magnitude of a Quasar to it's bolometric luminosity?

How can I convert the observed magnitude to Bolometric Luminosity? I know the relation for the star but should it be same for a Quasar? Basically I want to convert the X-axis of this plot to ...
84 views

### What happens if I were to add angular momentum to a maximally spinning black hole? [duplicate]

I am aware that a "naked singularity" is not possible. However, what would happen if I added angular momentum to a black hole near the maximal angular momentum limit? Does it asymptote?
120 views

### What is the farthest we can see into the universe?

Is there a limit in which the mass in space obscure the ability to detect anything farther even as technology progresses? Related: Can the range of the observable universe be extended through an ...
98 views

### Superscript-subscript uncertainty notation

While reading publications in astrophysics I've encountered this kind of notation (fictitious example): $$M = 6.1^{+0.6}_{-0.1} \times 10^{30} \textrm{ kg}.$$ Several examples are here, p. 2. I ...
81 views

### M87. What was the black hole before?

10 seconds before the M87 black hole was a black hole, what was it? A star 10 times the size of our solar system?
30 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 ...
41 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 ...
98 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 ...
86 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 ...
122 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?
123 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 ...
25 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 ...
94 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 ...
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?
60 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 ...
178 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 ...
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 ...
85 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?
157 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 ...
166 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 ...
85 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?
105 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'...
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) ...
99 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 ...
68 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.
356 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 “...
162 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 ...
54 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 ...
567 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?