Astrophysics Definition and 872 Threads

Astrophysics is a science that employs the methods and principles of physics in the study of astronomical objects and phenomena. Among the subjects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background. Emissions from these objects are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, astrophysicists apply concepts and methods from many disciplines of physics, including classical mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.
In practice, modern astronomical research often involves a substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine the properties of dark matter, dark energy, black holes, and other celestial bodies; and the origin and ultimate fate of the universe. Topics also studied by theoretical astrophysicists include Solar System formation and evolution; stellar dynamics and evolution; galaxy formation and evolution; magnetohydrodynamics; large-scale structure of matter in the universe; origin of cosmic rays; general relativity, special relativity, quantum and physical cosmology, including string cosmology and astroparticle physics.

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  1. Neha98

    Programs Applied or pure physics major is best for an astronomy career?

    I'm willing to make postgraduate studies in astronomy or astrophysics so which major is more suitable for me applied or pure phyics?
  2. X

    Help with a simple exercise in astrophysics.

    <Moderator's note: Moved from a technical forum and thus no template.> So i began studying on my own for my astrophycis class that will start on 2 weeks and i have trouble solving an exercise. So the exercise goes as follows: given that mbol=-2.5log(∫fλdλ)+Cbol and mbol=-26.83 for sun. Show...
  3. StillLearningToronto

    Using a CCD camera to solve physics problems

    (Sorry for Length) 1. Homework Statement You have decided to use a CCD camera to check if a 16th magnitude quasar is variable. You can presume that all of the light of your quasar falls on one pixel. You know that a star with a magnitude of 0 would deliver 1 × 10^9 photons/second to one pixel...
  4. AlphaLibrae

    How Does Subgiant Lifespan Vary with Stellar Mass?

    Homework Statement Can you estimate how the time spend on the subgiant branch varies with mass? Quantify this by writing table displaying the lifespan of subgiants in years for a given initial solar mass (1 solar mass, 3, 5, 10, 25, 60). Homework Equations I was not provided a relevant...
  5. Astroiaco

    I Why Do Astrophysicists Use νLν in Accretion Disk Emission Studies?

    Why in Astrophysics it is used νLν (where ν is the frequency and Lν is the luminosity at that frequency) in the emission spectrum of an accretion disk?
  6. V

    Neural networks - uses in Physics and Astrophysics?

    Hello, I'm not very familiar with neural networks, but it seems very interesting. I would like to ask how may I use it in physics, especially in astrophysics? I guess for some data mining? But could anyone show some concrete example of what it can do with data? Or if there is anything else...
  7. J

    Physics What can I do with a degree(s) in astrophysics?

    Can I get a job as an engineer or as a researcher, other than astrophysicist, with a degree(s) in astrophysics?
  8. astroman707

    What math is used the most in cosmology/astrophysics?

    Considering one is taking all the required math courses for a typical physics degree, what math electives are most crucial to the field of cosmology/theoretical astrophysics? Also, is it true that mathematical modeling courses(discrete and dynamical modeling across physics) are more important to...
  9. Andrew Church

    I Composition of the Sun: How We Know via Spectral Absorption Lines

    The question “how do we know the composition of the sun” falls shorts everywhere I look. 1. There is the spectral absorption lines. Explanations given how that works, indicate how we know the elements, but fails to tell us how we know about the preponderance of Hydrogen and Helium...
  10. I

    Ideas for a Project In Astrophysics

    Hey guys, I just wanted to get a few ideas about an Astronomy or Astrophysics project. I am doing this project for the purpose of an Extended Essay in the IB Diploma Programme. For those of you who don't know what means, it is basically a 4000 word essay on a scientific investigation The thing...
  11. Luke Coughlin

    Other Undergrad searching for advice in an academic career

    I dream of getting a PhD someday and focussing on astrophysics. I would want to work near the west coast so I could take advantage of their clear night sky. I'm only about 45 credits into my undergrad and would appreciate any tips I could implement while moving forward in this career. Also, what...
  12. donielix

    I White dwarf collapses into a neutron star and Energy is released

    Hello everyone. I am trying to solve a problem whose statement reads as follows: Neutron stars have radii of ##\sim 10## km. If we assume that before the collapse the nucleus of the white dwarf precursor has a mass equal to that of Chandrasekhar, estimate the energy generated in the collapse...
  13. A

    Best Astrophysics Masters Programs in Canada: Recommendations and Opinions

    Hi to whoever reads this, Some back ground info: I am a current undergrad student halfway through their degree, and I'm starting to think about what I'd like to do after I receive my diploma. I know I want to continue studying, and possibly move to a different country to do that. I know I can...
  14. F

    Books on Celestial bodies for a beginner

    Hi, I am an Alevel science student and looking forward to study Astrophysics in university. Can someone recommend books that are more like fact books with descriptions of celestial bodies, their composition, formations and etc. Like more like an encyclopedia than a book .
  15. kuolemaloki

    Engineering Astrophysics going on to Aerospace Engineering

    Hi all! I am currently doing my undergrad in Astronomy and Astrophysics and minoring in Computational Mathematics. I am starting to think about grad school and facing a dilemma: I would like to eventually receive a PhD in Astrophysics, but in the future I would possibly like to apply my...
  16. B

    How hard is it to get a job in astrophysics?

    im trying to become an award winning physicist (I know, I am ready for the grind, I am 15 and ready to start) how hard is it to first get a job in this area right out of college after a phd? any way to make 70-80k and go up to make 6-figure salaries in research for the government or in a lab...
  17. J

    Schools What is a good college for Astrophysics?

    Hi everyone! Recently I've been looking for a college that has a program that would be good for astrophysics or interplanetary physics. Any ideas for something slightly affordable in either Texas, or around Southern Michigan or the surrounding area (ideas from anywhere would be fine though)?
  18. Kiwimaster76

    Calculations for a theoretical planet + a little biology

    So I'm attempting to write a scientifically accurate story and i need some help with the planets characteristics. I have a few things set up already and need some educated guesses and ideas for how the rest will work. So to start with what i have: Planet name: Remvale Radius:~8370 miles Gravity...
  19. E

    Programs Maximizing Grad School Opportunities for Astrophysics After Military Service

    Hello all, I am going to college this fall and I will be studying physics with a concentration on astrophysics, I am a pretty good student and afterwards I will serve 5 years in the Navy as an officer. My question is, will the 5 years I spend in the Navy hinder my chances of getting into top...
  20. P

    I How many degrees / radians is one full orbit of the Earth?

    One day consists of slightly more than 360° of rotation (360.9856°) on it's axis (due to Earth's orbit around the Sun). I imagine that one orbit is also either > or < 360° around the sun, relative to the motion of the sun around some object. Is this true, or is the orbit of the Earth...
  21. I

    I What does L star mean in the Schechter function?

    I'm trying to understand the Schechter function, I read on Wikipedia that the L star term in the function is the 'characteristic galaxy luminosity where the power-law form of the function cuts off'. What does this mean exactly?
  22. I

    I Why Is the Velocity of an Oort Cloud Object Approximately Zero?

    I read that the the energy of an Oort cloud object is approximately zero, as in the potential energy plus the kinetic energy is equal to zero. I was also told that the radius was approximately infinite and the velocity is approximately zero. I understand why the radius is said to be infinite...
  23. D

    B Unraveling the Mystery of Universe Expansion: Exploring External Energy Sources

    So I was doing some studying and got a question on why the rate of expansion of the universe was increasing, and it got me thinking. Newton's first law states that an object in motion will remain in motion with a constant speed unless an external force acts upon it. If the expansion of the...
  24. M

    Programs UC London Astrophysics MSc vs Leiden Astronomy MSc (+ PhD)

    I need some advice with a tough choice between two great programs. On the one hand, I have University College London, a 1 year program in Astrophysics which covers 6 courses and an original research project. On the other hand, I have Leiden University, a 2 year program in Astronomy with ~12...
  25. A

    Calculating the Feeding Rate of Supermassive Black Holes to Power Quasars

    Homework Statement Quasars arise when supermassive black holes swallow nearby gas, or even entire stars. Their masses are typically 10&7 solar masses, and their luminosities are typically around 10&39 W. Hide the children! Roughly how many stars must one of these monsters eat per year, in order...
  26. mjda

    I Stellar Thermal Energy with no Nuclear source

    Can anyone enlighten me as to why the total thermal energy of a star will increase with time if the star has no nuclear energy source?
  27. mjda

    Resolving bodies at large distances

    Homework Statement If a 6.5m diameter telescope operates at wavelengths between 600nm to 2800nm, and for stellar densities similar to the Solar neighbourhood, what is the range of distances this telescope can resolve individual stars? Homework EquationsThe Attempt at a Solution My attempts so...
  28. ScienceGuy42

    Engineering Does an astrophysicist (PhD or post-doc) need computer engineering?

    Does an astrophysicist in research areas such as cosmic structure and evolution, galactic archaeology, and/or black hole phenomena require extensive skills (i.e. undergraduate degree) in computer systems engineering/computer engineering? The idea is to do a combined degree with computer...
  29. J

    Tension of Rope: Cosmonaut & Spaceship Orbit in Planetary Gravity

    Homework Statement What is the tension of this rope? Cosmonaut m=100kg is outside of spaceship M=5 tons on rope with length 64m. Cosmonaut along with his spaceship moves in orbit at a neglible distance. m=100kg M=5000kg L=64m Planet's mass 6*10^24 Planet's radius 6400km Homework Equations...
  30. R

    Textbook Recommendations for Solar Astrophysics

    I am seeking an undergraduate and graduate text for solar astronomy and astrophysics. By solar, I mean the Sun. Quantatative, too. Recommendations and testimonials appreicated. Thank you,.
  31. A

    Binary Stellar System: 15M⊙ & 10M⊙ Revisited

    Homework Statement A binary stellar system is made of one star with ##M_1=15{M}_\odot## and a second star with ##M_2=10{M}_\odot## revolving around circular orbits at a relative distance of ##d=0.001pc##. At some point ##M_1## explodes in a supernovae leaving a neutron star of mass...
  32. A

    What is the Magnetic Flux of a White Dwarf Derived from the Sun?

    Homework Statement The sun has a rotational period of 25 days. Finding the rotational period if it can shrink to form a white dwarf (##R_{WD}=10^3Km##). Knowing that the density of magnetic flux of the Sun on the surface is ##1 Gauss##, finding the magnetic flux of the white dwarf. Homework...
  33. A

    Binary system of stars (##\alpha## - centauri)

    Homework Statement ##\alpha##-Centuary is in a binary visual system with another star. Their separation, from their CM, is 8.0'' and 9.7''. The distance from the Earth is 1.31pc. Their revolution period around the CM is 80.1 years. I have to find masses and luminosities for each star. Homework...
  34. A

    I Exploring the Eddington Limit: Deriving the Formulation of Accretion Processes

    I am studyng accretion process on "Astrophysics in a nutshell" by Dan Maoz and I have some doubts about the derivation of the formula for the eddington limit. I understand what the edding limit is. The accretion rate cannot be arbitrarly large. The starting point is to consider an electron at a...
  35. ISamson

    B Massive Space Objects Have Connections to QM Math

    Massive Space Structures Have Surprising Connection to Quantum Mechanics Math Reading my daily science news I came across an interesting article that talks about how massive space objects have unexpected relationships to quantum mechanical mathematics. I was quite surprised to hear this, as I...
  36. W

    I Was the Universe Really Dark and Quiet After the Big Bang?

    It is postulated that there was a "Dark Age" subsequent to the so called Big Bang. The "matter" subsequent to the Big Bang would be composed of Quarks,if there was no light postulated for that time. This would indicate that the forces present would be only the Strong Force. The Strong Force of...
  37. binbagsss

    A What is the importance of EM measurements in astrophysics?

    I was asked this in a PhD interview and hit a blank, it seemed to open...
  38. Prof Sabi

    Programs What Shall I study -- astrophysics or aerospace engineering?

    I love astrophysics and cosmology, reading books of great men like Einstein, Stephen Hawking, NDGT and many more but I also have craze for rockets, their propulsion and aeronautical engineering like satellites and vehicles (SPACEX, NASA...) I am confused what Shall I do?
  39. binbagsss

    Other PhD interview question to 'why do you want to study astrophysics'

    My dissertation was basically a literature review of sean caroll lecture notes on general relativity. I got a first in this, and got offered phd interviews with the supervisors being aware of this so it must suffice? but I'm unsure how you explain the motives and conclusion of such a piece of...
  40. Mlesnita Daniel

    B What do I need to become an Astrophysicist?

    Hi! I just started high school and have developed a passion for cosmology and astrophysics. I would like to know if I really need to be very good at physics and mathematics (and if there is more that I need to be good at) and where do i find a job (spaces like N.A.S.A., SpaceX etc). Thanks for help!
  41. D

    Astrophysics Looking for an Astrophysics Textbook

    Currently a fourth year undergraduate student and haven’t had the opportunity to take any Astrophysics courses. In September I am starting a master’s degree in Physics but with an Astrophysics research project. I am told it is fairly easy to learn all the Astrophysics stuff in the first few...
  42. J

    What inspired this applied mathematician to join and contribute?

    Education: PhD, theoretical astrophysics, Cornell. MS, applied math, Michigan State Univ. Occupation: Applied mathematician (and a few other things), esp. in convolutive linear acoustics. Reason for joining: To make an occasional contribution to something worthwhile.
  43. starstruck_

    Programs Physics vs Astrophysics: Seeking Guidance for Major Switch

    Hey, so I’m in my first year of physics and astronomy right now (currently majoring in astrophysics) and I wanted time guidance, or insight in whether I should stay in this major or switch into physics. The reason I’m considering this is because I’m not enjoying learning astronomy- it’s a...
  44. U

    Programs BS Math to PhD Astrophysics, need MS Astrophysics or not?

    I'm currently completing a undergraduate BS Mathematics degree and want to go for a PhD in Astrophysics. I haven't decided on the precise area or topic yet, since there are so many fascinating areas of research, but I might have narrowed it down by the time I actually need to apply. A tutor...
  45. S

    Programs PhD programs -- I’m interested in both astrophysics and AMO physics

    Hi everyone, l have a situation and l thought you could help me. Actually, l live in the U.S. and want to apply for several phd programs, but I’m interested in both astrophysics and AMO physics, and l can’t decide which track l should pursue a phd in. I’ve talked to several professors from my...
  46. heavystray

    B Temperature based on colour index using Planck's law

    Hi, I'm trying to find temperature of stars using the stars' B-V magnitude by using the Planck law. However i do not know how to solve for T (assume other quantities are all given and determined first). Any idea how to do so? I already tried to do it but reach a dead end. Here I attached the...
  47. S

    Programs Which subfield of physics should I choose?

    Hi everyone; I have a question, and I hope you could answer it. Well, I have a bachelor degree in physics/computer science and I plan to go to a graduate physics program; however, I don’t know which subfield is good for me. I was looking for computational astrophysics, computational condensed...
  48. D

    Introducing a Florida Tech Student Studying Astrophysics and Computer Science

    Hey Peeps, I am David, I am studying astrophysics and computer science at Florida Institute of Technology. I am going to be taking mainly ALLL physics and math classes from here on out so I plan to make myself know on here! Thanks!
  49. W

    Courses Is astrophysics a prerequisite to study cosmology?

    I find it strange that astrophysics is not a pre-requisite to study cosmology in my university, students are only required to have taken general relativity. Is this a trend? How important would you say is astrophysics to learn cosmology?
  50. S

    B Why does the multiverse theory have only 4 levels?

    Why does max tegmark's and brian greene's levels of multiverses consider as the highest level the mathematical multiverse hypothesis if other authors like David Lewis consider that there could be also universes non described by maths? Why does it stop at level iv (mathematical universes...
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