astrophysics. (1 Viewer)

[BadMeetsEvil]

What did you write for parsecs?
-for relative brightness?
-for ceiphids: intrinsic and extrinsic?
And the last question?

Oh and do you think I can get a mark for the distance question cos I converted parsecs to lightyears..

 

[DavidWen]

parsecs: distance to a celestial body that subtends 1'' of parallax at the Earth.
Relative brightness: I1/I2=100^(M2-M1)/5
Cepheid: intrinsic
Last question:chemical composition,rotational velocity,translational velocity, density, luminosity class, surface temperature.......

 

[jniranjan]

Ah shit, for the last question i just bullshitted something, but i included 'velocity' (not translational or rotational), denisty, and chemical compostition. Hopefully I'll get around 3 or 4 for that. And the rest(of astrophysics) I got right i think! yay.

 

[khorne]

Ah shit, for the last question i just bullshitted something, but i included 'velocity' (not translational or rotational), denisty, and chemical compostition. Hopefully I'll get around 3 or 4 for that. And the rest(of astrophysics) I got right i think! yay.

You could talk about:

Spec techniques:

Temp, chemical comp, transistional/rotational velocty, density.

Photometric:

Spectral class and colour index, which can quickly estimate temp, colour, chemical composition. Photometric techniques can quickly scan the sky, and can be made sensitive for particular wavelengths. So you can find particular stars which radiate particular wavelenghts of energy. Spec data was used to construct photometric data, but now photometric data can be used to quickly scan for stars, while spec data gives us more accurate readings and predictions

 

[fxjkhr]

parsec - the distance from the sun to an object which subtends a trigonometric parallax angle of 1 arc second.
- Cepheid is an intrinsic variable - brightness periodically fluctuates due to varying equilibrium between radiation and gravitational pressures. Eclipsing binaries are extrinsic variables, as the brightness of the system varies due to stars eclipsing each other during orbit, and this process is external to the star.
- Last question: Just mentioning what each one does in terms of discoveries will only get a 3 or 4 - you have to explain that both can be used together to compliment each other and give an enhanced understanding of the universe Vs each one individually

 

[BadMeetsEvil]

So how do both techniques compliment each other?
I talked about finding apparent and absolute magnitude using them. Then find the distance of star using distance modulus formula. And I drew a hr diagram on how to find the absolute magnitude.

 

[DavidWen]

So how do both techniques compliment each other?
I talked about finding apparent and absolute magnitude using them. Then find the distance of star using distance modulus formula. And I drew a hr diagram on how to find the absolute magnitude.

Why are you still so keen to know, mate... doesn't matter anymore...
Anyway, using photometry you can work out the surface temperature. Now, you should have talked about determining the luminosity class(e.g. dwarf star, giant star, white dwarf, T-Tauri,....) when discussing pressure broadening. As you said, you can then locate it on the HR diagram. From the location on the HR diagram you can basically know anything you want to know about the star: distance, mass, evolution path, ...... applying Stefan-Boltzmann's Law the size of the star can also be calculated.

 

[SnowTau]

...So glad we did Medical Physics.