# Photometric and spectroscopic variability of the B5IIIe star HD 171219

## TL;DR

This study provides a detailed analysis of the pulsation and circumstellar activity of the Be star HD 171219, revealing nonradial g-modes, pulsation frequencies, and their potential link to mass-loss outbursts, using combined photometric and spectroscopic data.

## Contribution

It offers the first detailed detection and analysis of nonradial pulsation modes in HD 171219, correlating pulsation behavior with circumstellar outbursts.

## Key findings

- Detected multiple nonradial g-modes in HD 171219.
- Identified a pulsation quintuplet at ~1.113 c/d.
- Observed correlation between pulsation amplitude and outbursts.

## Abstract

We analyzed the star HD 171219, one of the relatively bright Be stars observed in the seismo field of the CoRoT satellite, in order to determine its physical and pulsation characteristics. Classical Be stars are main-sequence objects of mainly B-type, whose spectra show, or had shown at some epoch, Balmer lines in emission and an infrared excess. Both characteristics are attributed to an equatorially concentrated circumstellar disk fed by non-periodic mass-loss episodes (outbursts). Be stars often show nonradial pulsation gravity modes and, as more recently discovered, stochastically excited oscillations. Applying the CLEANEST algorithm to the high-cadence and highly photometrically precise measurements of the HD 171219 light curve led us to perform an unprecedented detailed analysis of its nonradial pulsations. Tens of frequencies have been detected in the object compatible with nonradial g-modes. Additional high-resolution ground-based spectroscopic observations were obtained at La Silla (HARPS) and Haute Provence (SOPHIE) observatories during the month preceding CoRoT observations. Additional information was obtained from low-resolution spectra from the BeSS database. From spectral line fitting we determined physical parameters of the star, which is seen equator-on. We also found in the ground data the same frequencies as in CoRoT data. Additionally, we analyzed the circumstellar activity through the traditional method of V/R emission H{\alpha} line variation. A quintuplet was identified at approximately 1.113 c/d (12.88 {\mu}Hz) with a separation of 0.017 c/d that can be attributed to a pulsation degree l~2. The light curve shows six small- to medium-scale outbursts during the CoRoT observations. The intensity of the main frequencies varies after each outburst, suggesting a possible correlation between the nonradial pulsations regime and the feeding of the envelope.