Bibcode
Gutiérrez-Soto, J.; Fabregat, J.; Diago, P. D.; Briquet, M.; Uytterhoeven, K.; Suárez, J. C.; Mathias, P.; Rainer, M.; Poretti, E.; Neiner, C.; Emilio, M.; Frémat, Y.; Andrade, L.; Janot-Pacheco, E.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 603, id.A41, 7 pp.
Fecha de publicación:
7
2017
Revista
Número de citas
1
Número de citas referidas
0
Descripción
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 have
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 (i = 90°). 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 violet to red emission Hα line variation. A
quintuplet was identified at approximately 1.113 c d-1 (12.88
μHz) with a separation of 0.017 c d-1 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.
The CoRoT space mission was developed and operated by the French space
agency CNES, with participation of ESA's RSSD and Science Programmes,
Austria, Belgium, Brazil, Germany, and Spain. This work is partially
based on observations made with the 3.6-m telescope at La Silla
Observatory under the ESO Large Programme LP185.D-0056.