Quick question

[Hungry4info]

I did a SIMBAD search on a star and under the 'flux' section, it told me:

B 13.158
V 13.524
I 13.894
U 11.894
R 13.689
J 14.332
H 14.490
K 14.548

Now, if I understand correctly, V is visual magnitude. Are B, I, U, R, etc other wavelengths (IR, Ultraviolet, etc)? If so, what do each of them correspond to?

(please, no non-serious answers, this is a serious question and it should be responded to as such).

[hank]

I did a SIMBAD search on a star and under the 'flux' section, it told me:

B 13.158
V 13.524
I 13.894
U 11.894
R 13.689
J 14.332
H 14.490
K 14.548

Now, if I understand correctly, V is visual magnitude. Are B, I, U, R, etc other wavelengths (IR, Ultraviolet, etc)? If so, what do each of them correspond to?

(please, no non-serious answers, this is a serious question and it should be responded to as such).

This might be of help:

http://spiff.rit.edu/classes/phys445/le ... olors.html
http://www.mso.anu.edu.au/~bessell/araapaper.pdf

- Hank

[revent]

I did a SIMBAD search on a star and under the 'flux' section, it told me:

B 13.158
V 13.524
I 13.894
U 11.894
R 13.689
J 14.332
H 14.490
K 14.548

Now, if I understand correctly, V is visual magnitude. Are B, I, U, R, etc other wavelengths (IR, Ultraviolet, etc)? If so, what do each of them correspond to?

These are stellar fluxes (or luminosities, measured in magnitudes) measured through different spectral filters. These are filters that only pass frequencies of light between certain limits, and are standardized. And yes, the V filter is designed to pass the visual band that the human eye sees, so a 'V' magnitude corresponds to a traditional visual magnitude.

In the Johnson system, U is centered around 364 nm, B is 442 nm, and V is 540 nm. The differences between these magnitudes are called 'color indexes', and are used to classify stars by type. Basically, the idea is that the star is dimmed by distance equally in all bandpasses, so the B-V or U-B measures should be the same for a particular type of star, no matter how far away it is.

In the case of the UBV system, it's been around since the days of glass photographic plates, and so the filters used are actually designed to match certain old photographic emulsions.

For more info, look here: http://en.wikipedia.org/wiki/Photometric_system

[Hungry4info]

Thank-you both for your replies.