HD,139614 is known to be a $sim$14-Myr-old, possibly pre-main-sequence star in the Sco-Cen OB association in the Upper Centaurus-Lupus subgroup, with a slightly warped circumstellar disc containing ring structures hinting at one or more planets. The stars chemical abundance pattern is metal-deficient except for volatile elements, which places it in the $lambda$ Boo class and suggests it has recently accreted gas-rich but dust-poor material. We identify seven dipole and four radial pulsation modes among its $delta$ Sct pulsations using the TESS light curve and an echelle diagram. Precision modelling with the MESA stellar evolution and GYRE stellar oscillation programs confirms it is on the pre-main sequence. Asteroseismic, grid-based modelling suggests an age of $10.75pm0.77$ Myr, a mass of $1.52pm0.02$ M$_{odot}$, and a global metal abundance of $Z=0.0100pm0.0010$. This represents the first asteroseismic determination of the bulk metallicity of a $lambda$ Boo star. The precise age and metallicity offer a benchmark for age estimates in Upper Centaurus--Lupus, and for understanding disc retention and planet formation around intermediate-mass stars.
تحميل البحث