Astro Definition and 68 Threads

I can see the lack of input is frustrating, i too am so frustrated about the lack of testable results, but that is of no concern, so long as there exists a way forward, what is the way we should go?

1. Hydrogen and Helium recombination Hydrogen recombines at a redshift of approximately z=1200, with recombination starting already at z=1600. a. What was the ratio of the number density of hydrogen-ionizing photons (i.e. photons with energies E > 13.6eV) to the number density of hydrogen...

Hi folks, I am trying to choose between two PhD scholarships. They are both at the same university & both research groups have excellent reputations. I'm being pressured by the university to make a decision by Monday. They're British PhDs so I'm assigned to my research topic right from the...

sombodyyyyyyyyy hellllllllllp me Astroblaster: When a large ball is dropped, with a smaller one stacked on top of it, onto a hard surface, the smaller ball will often rise much higher than it would if dropped onto the same surface by itself while the larger ball hardly bounces at all...

H1 means hydrogen with mass 1, H2 means hydrogen with mass 2 (has a neutron), etc 1) H1 + H1 -> H2 + positron + neutrino + 1.18 Mev (+0.26MeV) 2) H1 + H2 -> He3 + photon + 5.49MeV 3) He3 + He3 -> He4 + 2*H1 + 12.86 MeV (The neutrino produced in 1 for all practical purposes do not...

The neutrino flux from supernova 1987A was estimated to be 1.3e14 m^-2 at the Earth. SN 1987A occurred in the Large Magellanic cloud, which is located at a distance of 50 kpc. If the average energy per neutrino was 4.2 MeV, estimate the amount of energy released in the form of neutrinos during...

Just wanted to take a second and say thank you to all of the people - Astronuc, Doc Al, nrged, and company - that helped me (and others) along on hairy questions, with issues of clarification, and so forth. I took my physics I final this afternoon and am under the impression that the latter...

Hello all, for the past few weeks my friend and me have been working on a project involving simulation of orbital objects interaction. For example, one could see how everything looks if he/she entered all the details about the objects (that is: mass, position and velocity vector). The...

hey guys anyone got any ideas on this: f/19 cassegrain focus of a 408mm telescope. ccd is 12.3mm long, each pixel is a square of side 24 x 10E-6 m, grating used has 1200lines/mm 1. = the spectrum is imaged on a ccd with a zoo lens such that the dispersion is 3.3nm/mm. what is the range of...

Hi there, I'm in the process of applying to graduate schools and am having some trouble deciding what schools to pick. At my current school there is no Astronomy/Astrophysics going on (there's primarily condensed matter, optics /photonics, some bio physics and high energy stuff being done). I...

I am a sceptical TV documentary-maker currently involved with a team making a film about 2012, the end of the Mayan Calander and involved in this is a claim that a special alignment of the Earth relative to the centre of our galaxy opens a portal (like stargate) :rolleyes: that the indigenous...

Astro, did you intend to add something here?

Try talking about astro phys to *the man in the street*, and there is no interest whatsoever, how can this be redressed ? i can tell you the black eyed peas are more of interest to the GP.

Historical Meeting: Astro & Clausius in SD! Yeah man! Although it was a very fast meeting, we were talking in my new place at San Diego!. A nice guy!. And yeah, his beard is original (I tried to pull out his beard hair and after some Astro screams I realized is beard is true!). Behind a...

have solved the lane - emden eqn numerically for scaled radius, and the derivative of scaled pressure with respect of scaled radius, are given the eqn of state, n, and mass, how would i go about working out the central density and the radius? thanks

Anybody knows what kind of web searcher have Astro installed in his computer?. It's amazing to see how he show cents of links for everything people ask him. An example: https://www.physicsforums.com/showthread.php?p=706681#post706681 My Google is more modest. Astro, I crown you as the...

A bit of lighter fare then usual but this seemed like the right place to put it. My roomie just sent me this following comic. I thought it was pretty good myself and thought some other astro nerds would agree! :biggrin: http://cheston.com/pbf/PBF039BCSpaceLove.jpg

Sorry for disturbing, i am a college student and feel interested in physics. So i would know some fundamentals Q about ASTROPHYSICS. 1) why do we study in astrophysics and what are our targets and what we want to get? 2) why astrophysics is divided in theoretical and observatable? what is the...