Is the Sun's luminosity in specific filters greater than its overall luminosity?

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SUMMARY

The discussion centers on the luminosity of the Sun in specific infrared filters (J, H, K) compared to its overall bolometric luminosity. The absolute magnitudes for these filters are J: 3.64, H: 3.32, and K: 3.28, while the bolometric absolute magnitude is approximately 4.72. The confusion arises from the interpretation of the equation M2-M1 = -2.5 log (L2/L1), which suggests that the Sun's luminosity in these filters could be greater than its bolometric luminosity. The comparison with Vega highlights that differences in spectral energy distribution can lead to variations in perceived brightness across different filters.

PREREQUISITES
  • Understanding of absolute magnitude and luminosity concepts
  • Familiarity with photometric filters, specifically J, H, and K
  • Knowledge of blackbody radiation and spectral energy distribution
  • Proficiency in using logarithmic equations in astrophysics
NEXT STEPS
  • Research the relationship between absolute magnitude and luminosity in astrophysics
  • Study the spectral energy distribution of stars, focusing on blackbody radiation
  • Explore the differences in photometric systems, particularly JHK versus UBV
  • Examine the properties of Vega and its comparison to the Sun in various filters
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Astronomers, astrophysics students, and anyone interested in stellar luminosity and photometric analysis will benefit from this discussion.

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I'm trying to calculate the luminosity of the sun in the infrared (J, H and K filters). According to http://mips.as.arizona.edu/~cnaw/sun.html, the absolute magnitudes of the Sun in each of these filters are

J: 3.64
H: 3.32
K: 3.28.

The absolute bolometric magnitude of the Sun is about 4.72. What I can't quite wrap my head around is this: how is it possible that the absolute magnitude in specific filters is smaller (as in brighter) than the bolometric absolute magnitude? Does this not mean that the luminosity of the Sun in each of these filters is greater than the bolometric luminosity? That is what the equation M2-M1 = -2.5 log (L2/L1) would seem to imply (though I'm not entirely sure if it's legal to have M1 as M_bol and M2 as M_J for instance; I'm fairly certain the filters have to be the same).

I'm sure it's just an interpretation error on my part. I understand that as a blackbody, to find the total luminosity the emission must be integrated over all wavelengths, but it doesn't make sense to me that the Sun would be brighter in one filter than in ALL filters. (Looking at the V magnitude as well this implies that the Sun is brighter in the IR than the visible but the peak of the blackbody distribution of the Sun is clearly in the visible.)

Any help is appreciated!
 
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I believe they are comparing the brightness of the Sun to Vega. I'm not sure, but I think that Vega, being a higher temperature than the Sun, puts out more of it's energy in the higher energy wavelengths, like the UBV bands, than the lower energy bands, like the JHK. So when you compare the two perhaps the lower difference in the JHK bands is due to the different shape of the spectrums.
 

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