The pre-main-sequence star HD 34282: a very short-period δ Scuti-type pulsator

Abstract

HD 34282 has been found to pulsate during a systematic search for short‐term photometric variability in Herbig Ae/Be stars with the goal of determining the position and size of the pre‐main‐sequence instability strip. Simultaneous Strömgren photometry is used in the frequency analysis, yielding two frequencies with values of ν1= 79.5 and ν2= 71.3 cycle d−1. The light curve with the largest amplitude is that of the u band. This behaviour, which is not common for δ Scuti stars, is explained as pulsation in a high radial order in stars near the blue edge of the instability strip. The main period, with a value of 18.12 min, represents the shortest period observed so far for a δ Scuti‐type pulsator. A seismic modelling, including instability predictions and rotation effects, has been attempted. It is found that both main‐sequence and pre‐main‐sequence models predict modes in the range of 56 to 82 cycle d−1 (between 648 and 949 μHz), corresponding to oscillations of radial order n from 6 to 8. The highest of the observed frequencies only becomes unstable for models of low metallicity, in agreement with results from spectroscopic measurements.

A search for rapid pulsations among nine luminous Ap stars

“…She predicted that more luminous and evolved Ap stars may pulsate with lower frequencies (0.67-0.83 mHz) which makes it harder to detect them in the typically short high-speed observing runs. Note that this frequency range overlaps with the highest δ Sct frequencies, such as for HD 34282 (0.92 mHz, Amado et al 2004). Alternatively, she proposed that this absence of known evolved roAp stars could reflect a real deficiency in the fraction of pulsators in that region of the Hertzsprung-Russell (HR) diagram, resulting from the fact that the magnetic field is less likely to suppress envelope convection in more evolved stars.…”

Pulsating stars in the region of Carina Nebula

“…The first δ Scuti-type pulsations were found in PMS stars among members of the open cluster NGC 2264 [2]. Until now, about 30 PMS pulsating stars are known in open clusters [18,17,24,23,25], as well as in the field population of Herbig Ae stars [1,3,4,11,12,13,14,16,19,20,21].…”

Asteroseismology with SuperWASP

“…For example, HD 34282 (V1366 Ori) has an apparently random noise lightcurve (Fig. 4) but the periodogram recovers the 79.5 d −1 and 71.3 d −1 δ Scuti-type pulsations known to be hiding in the dusty environment of this pre-main sequence star (Amado et al 2004). …”