1. ### Abour Riccardo Giacconi's opinion about the multiverse?

Riccardo Giacconi (1931-2018) was an italian astrophysicist who was awarded with the Nobel prize in physics back in 2002 for his important contributions to astrophysics. Since he was an astrophysicist he must have heard about the multiverse hypothesis, but I have not found a single paper or...
2. ### Optical depth using Bremsstahlung emission coefficient

Equations I think may be relevant:
3. ### I Asteroid Response Help

(If anyone could provide links to information it would be greatly appreciated.) I'm currently taking a class on threats from outer space and have to write a paper on something that could be done in response to an asteroid/meteor coming towards Earth. One of the quickest responses would be to...
4. ### Numerically simulating stellar pulsation using a "one zone" model

The question is taken from An Introduction to Modern Astrophysics by Carroll and Ostlie. I did manage to do the entire question and plot the relevant graphs but I just wanna to investigate a bit more. For example I wanna look at how the graph would like in the case of the Sun. I don't know what...
5. ### I The solar system and the Coriolis effect

After concluding an investigation about the coriolis effect, I wondered how this phenomenon affected the solar system and in particular the moon. Since the moon is a body that moves within the rotating system formed by the sun and the earth, an apparent deviation in the moon's path would be...
6. ### Physics From Software Engineering to Astrophysics Grad School

Greetings everyone. I am an undergrad currently majoring in Computer Science with a minor in Physics. I entered college as a physics student because I wanted to pursue astrophysics as a career. After my first 1.5 years of courses and a summer research experience, I concluded that a career in...
7. ### B High school Astrophysics Research Project Suggestions Please

Hi, so I'm currently a senior high school student and I'm doing a research project on Astrophysics. I just need help on picking a topic as I know there is a lot out there. I need a project idea that is current but not too challenging as I am limited with resources. Thanks.
8. ### I Radius of Curvature confusion

$$1 - \Omega_{tot} = \Omega_κ = \frac{-κc^2}{R_0^2H_0^2}$$ For ##\Omega_κ=-0.0438## we get a some value for ##R_0##. This ##R_0## is the radius of the observable universe right ? Not the universe ?
9. ### I Help With Simple Orbital Modeling

I have yet to decide on values for the mass of the fixed object, M, the mass of the moving celestial body, m, the initial velocity, v, and the distance between the two objects, r. I will most definitely decide on a larger mass M because I would like the celestial body to spiral in towards the...
10. ### (Astrophysics) Determine the apparent transverse velocity from a radio image

See the attached figure. I understand that we look for the apparent transverse velocity v , for example through v = d/t (d - distance, t - time). The distance to the galactic nucleus is known as D. Though Im not sure how to read off the time from this figure.
11. ### Courses What is it like to work as an Astrophysicist or an Aerospace Engineer?

Hi all. I'm currently an aerospace engineering undergraduate student in my second year, but I'm going through a very confusing process of second guessings and would greatly appreciate advice from older people who work in the Aerospace or in the Physics/Astronomy fields to help me compare the...
12. ### I What are the potential effects on electricity due to Earth's magnetic field reversal?

What is/are the potential or theoretical effect on electricity due to reversal of planetary magnetic field? Would circuitry continue to function or would knowledge and understanding need re-evaluating as a result of a reversal of our magnetic field on planet Earth? Note: this is not a homework...
13. ### B What is the black that we see in the night sky?

Summary: Can black means many thing? The black we see in night sky has to mean many things First of all, from point of views of human eyes then the photons can't reach our eyes so it appears black. Secondly, the objects appear smaller as we go farther from that object. So, at some point object...
14. ### A Derivation of radial momentum equation in Kerr geometry

I am trying to derive the radial momentum equation in the equatorial Kerr geometry obtained from the equation $$(P+\rho)u^\nu u^r_{;\nu}+(g^{r\nu}+u^ru^\nu)P_{,r}=0 \qquad$$. Expressing the first term in the equation as $$(P+\rho)u^\nu u^r_{;\nu}=(P+\rho)u^r u^r_{;r}$$ I obtained the...
15. ### B Intensity of Spherical Shell of Stars

Given that L is the luminosity of a single star and there are n stars evenly distributed throughout this thin spherical shell of radius r with thickness dr, what is the total intensity from this shell of stars? My calculations were as follows: Intensity is the power per unit area per steradian...
16. ### Setup for Spherical Astronomy Problem

My apologies for not detailing my attempts at a solution; I'm not sure how to to digitally illustrate or describe the various setups I attempted before looking at the solution to this problem. I am also ONLY asking about the setup, though I included the full question for context. The solution to...
17. ### Mass Transfer in a Binary Star System

Homework Statement: A binary star system consists of M1 and M2 separated by a distance D. M1 and M2 are revolving with an angular velocity w in circular orbits about their common center of mass. Mass is continuously being transferred from one star to the other. This transfer of mass causes...
18. ### B What’s more “important": GR or QM?

Let’s say to the average Astronomer conducting research; generalizing the research to “astronomy” ; which would be more useful for the “average” Astronomer on a day to day basis: Quantum Mechanics or General Relativity? Obviously most are, but which so more? Which would be referred to more?
19. ### B How well should Astronomers know General Relativity?

I know that it would vary depending on the type of research a specific astronomer would be doing ( Astrophysics/Cosmology research versus an Astronomer researching exoplanets ) ; but in your opinion, “how much” or “how well” should an Astronomer with a graduate degree in Astronomy know General...
20. ### Schools What are the best Colleges for Astrophysics?

I just finished my Junior year in high school in Houston. I am currently pursuing a degree in Astrophysics. I have been looking at Rice and Cal-tech as my best options, but in case I cant make it into those school I am considering Texas A&M, University of Texas for being in state. As well as...
21. ### B Black holes and the first law of thermodynamics

The first law of thermodynamics states that matter can only be transferred from one state to another, and cannot be truly destroyed. What happens to matter consumed by a black hole? What happens to it and where does it go? Does the first law still hold true?
22. ### How can we determine the distance to the Galactic center?

Problem Statement: We can use "spectroscopic line shift of S2" and "its proper motion", but I don't have any idea what dose this sentences mean. please show me details!! Relevant Equations: spectroscopic line shift
23. ### Courses What undergrad topics do astronomy grad programs expect you to have taken?

I was speaking with my prof about the requirements for the applied physics major track offered at my school, and she said some very surprising things. Just for context, I’m interested in pursuing observational astrophysics/astronomy in grad school later. She said that I can skip diff equations...
24. ### I Gaussian probability distribution of formation PBH

Hello. If we consider PBH formation from collapse of large density perturbation in the early Universe, a mass PBH depends on density contrast as And δ must be larger then . Also we have β — an abundance of black holes, it's the ratio of the PBH energy density to the total energy density, this...
25. ### A Abundance and mass spectrum of PBH

Hello. I'm trying to study primordial black holes for my work, but I still can't understand what are abundance and mass spectrum? Could you explain? Thanks in advance.
26. ### A What does the image of the black hole say about general relativity?

We all heard about the "photo of black hole". My question is: did this image show any hints of physics beyond general relativity? I read once (not sure where) that the apparent size of black hole shadow is very sensitive to corrections to general relativity. Add some minor correction and the...
27. ### How to use the Bremsstrahlung flux to analyse a medium?

I don't know where to even begin?
28. ### I The Confinement Radius of a Cosmic Ray (Galactic vs. Extra-galactic)

If we want to show whether or not a specific Cosmic Ray particle is confined to our galaxy we must use the Larmor radius (relativistic version), r = γmc / qB Considering a 10^14 eV proton and assuming the galactic magnetic field strength is 10^−11 T, show that the particle is confined to the...
29. ### Courses What undergrad electives should be taken when pursuing astrophysics?

Hi, I go to a small liberal arts college and I'm majoring in physics. The college I attend has a VERY unique academic curriculum, with few required core courses, and one can have an oxford style tutorial in almost any area in physics, no matter how advanced. I want to pursue graduate school in...
30. ### Programs Diploma thesis - Neural Network Application in Physical Problems

Hello everybody. I am currently on my last year of Computational Physics education. More and more I am interested in Machine Learning and Neural Network. Time has come for me to choose diploma work thesis, so I am searching for interesting ideas where I can merge my interest in neural networks...