The TAJY476K016RNJ: This is a KYOCERA AVX TAJ series molded tantalum capacitor — 47 µF, 16 V rated, ±10% tolerance, with a 700 mOhm ESR at 100 kHz. The 2917 (7343 Metric) case is the standard large-footprint tantalum size, 7.30 mm x 4.30 mm, seated height 2.00 mm max. It's a surface-mount part, so it reflows alongside the rest of the board — no hand-soldering required unless you're doing a repair. That means it's at home on an avionics power supply, a satellite's secondary rail, or a downhole tool that sees 125°C at the bottom of a well.
What the ESR tells you about the circuit
700 mOhm ESR is typical for a 47 µF tantalum in this case size. At 100 kHz, the impedance is dominated by the ESR, so the ripple current rating is set by the self-heating limit. For a 16 V rail switching at a few hundred kHz, this cap handles the output ripple without cooking itself — but the ESR does add a few milliohms to the total output impedance, so if you're after ultra-low noise, a polymer cap might be a better fit.