Asteroseismic properties of young pulsators in the Perseus molecular cloud. Discovery of period-spacing patterns in HD 281229

Very young pulsating stars, including pre-main sequence pulsators, provide a rare opportunity to probe stellar interiors and investigate rotation during the earliest phases of stellar evolution. However, they remain relatively unexplored, particularly in the intermediate-mass regime. We aim to identify and characterise young pulsating stars in the Perseus molecular cloud using photometric data from the Transiting Exoplanet Survey Satellite (TESS). We compiled -based membership catalogues for the Perseus molecular cloud, applied selection criteria to isolate young intermediate-mass stars, and extracted light curves from TESS full-frame images. Variability classification was performed using Lomb--Scargle periodograms and iterative pre-whitening. For confirmed pressure-mode pulsators, we estimated the frequency of maximum pulsation power, ν_ Gaia max . For gravity-mode candidates, we searched for period-spacing patterns and fitted them using the traditional approximation of rotation. From the 148 membership-selected targets, we identified eight pressure-mode pulsators and two objects showing possible gravity-mode pulsations. We also analysed the previously known δ Sct star V705 Per, bringing the total sample to 149 targets. One of the gravity-mode pulsators, HD 281229, is the youngest star known to date with a detected and modelled period-spacing pattern. By simultaneously fitting the dipole and quadrupole period-spacing patterns, we estimate an asymptotic period spacing of (Π_0=4776 ) and a near-core rotation frequency of (f_ =1.317 ^ s rot d -1 ). These results highlight the potential of asteroseismology to probe the internal structure and rotation of very young stars. The detected period-spacing pattern in HD 281229 shows that gravity-mode asteroseismology can provide meaningful constraints on the properties of stars at early evolutionary stages.