AAVSO: American Association of Variable Star Observers

Data Analysis of Bright Main-Sequence A- and B-type Stars Observed Using the TESS and BRITE Spacecraft (Abstract)

Volume 48 number 2 (2020)

Joyce A. Guzik
Los Alamos National Laboratory, MS T082, Los Alamos, NM 87547; joy@lanl.gov
Jason Jackiewicz
Department of Astronomy, New Mexico State University, Las Cruces, NM
Andrzej Pigulski
Instytut Astronomiczny, Uniwersytet Wrocławski, Wrocław, Poland
Giovanni Catanzaro
INAF—Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy
Michael S. Soukup
Los Alamos National Laboratory (retired), Albuquerque, NM 87111
Patrick Gaulme
Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Web 3, 37077, Göttingen, Germany
Gerald Handler
Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland
The BRITE Team


(Abstract only) During the last two years we have received long time-series photometric observations of bright (V mag < 8) main-sequence A- and B-type stars observed by the NASA TESS spacecraft and the Austria-Poland-Canada BRITE satellites. Using TESS observations of metallic-line A (Am) stars having peculiar element abundances, our goal is to determine whether and why these stars pulsate in multiple radial and nonradial modes, as do the δ Scuti stars in the same region of the H-R diagram. The BRITE data were requested to investigate pulsations in bright (V around 6 mag) A- and B-type stars in the Cygnus-Lyra field of view that had been proposed for observations during the now-retired NASA Kepler mission. Of the 21 (out of 62 proposed) Am stars observed by TESS so far, we find one δ Sct star and two δ Sct / γ Dor hybrid candidates. Of the remaining stars, we find three γ Dor candidates, six stars showing photometric variations that may or may not be associated with pulsations, and eight stars without apparent significant photometric variability. For the A- and B-type stars observed by BRITE, one star (HR 7403) shows low amplitude low frequency modes that likely are associated with its B (emission) star properties; one star (HR 7179) shows SPB variability that is also found in prior Kepler data, and two stars (HR 7284 and HR 7591) show no variability in BRITE data, although very low amplitude variability was found in TESS or Kepler data. For the TESS and BRITE targets discussed here, follow-up ground- and space-based photometric and spectroscopic observations combined with stellar modeling will be needed to constrain stellar parameters and to understand the nature of the variability.