Magnitudes—how astronomers express brightnesses of stars—are confusing to those unfamiliar with them, to say the least. They use a modified version of base-10 logarithms. The smaller—or more negative—the magnitude, the brighter the object. An object with a magnitude of zero is not an object with no brightness but instead is rather bright.
References
1.
C.
Sirola
, “I love my baffling, backward,
counterintuitive, overly complicated magnitudes
,” Phys.
Teach.
55
, 124
–115
(2017
).2.
A.
Pringle-Pattison
, “Weber's
law,” in Encyclopædia Britannica
,
edited by Hugh
Chisholm
(Cambridge
University Press
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), 11th ed., Vol.
28
, pp. 458
–459
.3.
“
Astronomical Magnitude
Systems
,” https://lweb.cfa.harvard.edu/∼dfabricant/huchra/ay145/mags.html, accessed
Jul. 4, 2022
.4.
“Flux” as used in astronomy is defined as power per
unit area, more commonly referred to as “intensity” in physics and not related to the
physics usage of the term flux.
5.
Vega—one of the brightest stars in the night
sky—was once used as the reference for zero magnitude. Vega is now known to rotate
extremely rapidly for a star, meaning its surface temperature changes significantly across
its surface, making it a poor choice of standard. Astronomers no longer depend on one
individual star to set magnitude standards.
6.
Readers can access the
supplemental material at TPT Online at https://doi.org/10.1119/5.0146515, under the
Supplemental tab.
© 2023 Author(s). Published under an exclusive license by American Association of Physics Teachers.
2023
Author(s)
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