O_o Rion

Silly question here, but I am not getting a certain part in the solution in a problem. Evaluate the integral of [(sin(ln(39x)))/x]dx. We are supposed to take u=ln(39x), and get du=(1/x)dx, and the then whole thing is simply solved using integration formul...

Hi. In an integration solution, the integral of (1/(sqrt (8-u squared)) is written as arcsin(u/sqrt 8), but I don't see how they got it. When I did it I got (1/8)*(arcsin(u*sqrt8)). What I did was take sqrt8 common in the denominator to get it in the form...

If stars should always be visible, where should you be located on earth? Can I answer this considering the celestial sphere and the ecliptic? I am not sure how...

Integral of x sq/(1+x sq) dx I am not sure how to do this, am i supposed to do partial fractions to break it up? Or is it just some simple substitution?

(a) From the absorption lines, we were able to determine that the star (phi)-Fictus has spectral classification F7V and color index B-V=0/48. What is the mass M(phi) of the star in solar masses? (b) Spectroscopic parallax, when corrected for reddening, yi...

Ohhh yeah! Got it! Thanks!

Thanks!

But how did you get Integral of x sq/(1+x sq) dx = integral (1/2)u^(1/2) du du= 2xdx, from there i got, integral xsq/(1+x) dx = (1/2) integral[ (sqrt (1-u))/u ]du Did i do anything wrong?

Well it's definitely a main sequence star since it's F7V (V--> main sequence, right?) but I'm a bit confused about how to find the luminosity (and thus the absolute magnitude) from the b-v index, all the H-R diagrams in our book are luminosity vs surface...