Searching for $\delta$ Scuti-type pulsation and characterising northern pre-main-sequence field stars

TL;DR

This study identified new pre-main-sequence and main-sequence δ Scuti and γ Doradus pulsators through four years of photometric monitoring, expanding understanding of stellar variability and pulsation characteristics.

Contribution

It provides the first identification of multiple PMS δ Scuti and β Cephei stars using extensive uvbyβ photometry and variability analysis.

Findings

Detected five PMS δ Scuti stars and three probable β Cephei stars.

Confirmed two additional PMS δ Scuti stars.

Discovered three new δ Scuti and two γ Doradus stars among main-sequence objects.

Abstract

A photometric variability study of a sample of northern field stars, which previously classified as either PMS or Herbig Ae/Be objects, has been undertaken with the purpose of detecting {\delta} Scuti-type pulsations. Determination of physical parameters for these stars has also been carried out to locate them on the HR diagram and check the instability strip for this type of pulsators. Multichannel photomultiplier and CCD time series photometry in the uvby Str\"omgren and BVI Johnson bands were obtained during four consecutive years from 2007 to 2010. The light curves have been analysed, and a variability criterion has been established. Among the objects classified as variable stars, we have selected those which present periodicities above 4 d^(-1), which was established as the lowest limit for {\delta} Scuti-type pulsations in this investigation. Finally, these variable stars have been placed in a colour-magnitude diagram using the physical parameters derived with the collected uvby{\beta} Str\"omgren-Crawford photometry. Five PMS {\delta} Scuti- and three probable {\beta} Cephei-type stars have been detected. Two additional PMS {\delta} Scuti stars are also confirmed in this work. Moreover, three new {\delta} Scuti- and two {\gamma} Doradus-type stars have been detected among the main-sequence objects used as comparison or check stars.