What timescale does $ ext{UV}$ Luminosity ($L_{ ext{UV}}$) typically probe for star formation?
Answer
$ ext{10}^7$ years
Ultraviolet (UV) luminosity is directly linked to the birth of very massive, hot O and B type stars, which have masses greater than about eight times that of the Sun ($M > 8 M_{ ext{odot}}$). Because these massive stars burn through their nuclear fuel extremely quickly due to their high luminosity and mass, their main-sequence lifetimes are very short, estimated to be around $10^7$ years. Consequently, observing the UV emission provides a near-instantaneous snapshot of star formation activity occurring at the present moment or within the very recent past, making it a measurement sensitive to the most current birth events.
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