Spectroscopic frequency and mode identification of γ Doradus stars HD 109799 and HD 103257. Issue 1 (16th June 2021)

• Record Type: Journal Article
• Authors: Shutt, T R; Brunsden, E; Pollard, K R
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 507:Issue 1(2021)
• Page Start: 1149
• Page End: 1156
• Publication Date: 2021-06-16
• Subjects: line: profiles -- techniques: photometric -- techniques: spectroscopic -- stars: individual -- stars: oscillations -- stars: variables: general; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab1972
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Following frequency and mode identification of two candidate γ Doradus stars, HD 103257 and HD 109799, both can be categorized as bona-fide members of the class. Over 250 high-resolution spectra of the two stars were collected at University of Canterbury Mount John Observatory (UCMJO) using the High Efficiency and Resolution Canterbury University Large Echelle Spectrograph ( HERCULES ) spectrograph. The spectra were cross-correlated with a synthetic δ-function template to produce line-profiles and further augmented with high-quality photometry from the Transiting Exoplanet Survey Satellite ( TESS ) mission, the Wide Angle Search for Planets ( WASP ) archive, and HIPPARCOS catalogue for frequency and mode analysis. Frequency analysis was carried out using FAMIAS and SigSpec. Two pulsation frequencies were identified in the spectra for HD 103257: 1.22496 ± 0.00001 and 1.14569 ± 0.00002 d −1, explaining 58.9 ${{\ \rm per\ cent}}$ of the variation across the line profiles. Both frequencies were characterized with best-fitting modes of (ℓ, m ) = (1, 1). Two pulsation frequencies were identified in the spectra for HD 109799: 1.48679 ± 0.00002 and 1.25213 ± 0.00002 d −1, explaining 32.6 ${{\ \rm per\ cent}}$ of the variation across the line profiles. Both frequencies also yielded individual mode fits of modes (ℓ, m ) = (1, 1). The excellent quality photometry from TESS observations has proven complementary to the work herein, and will provide a meaningful opportunity for deeper analysis of additional stars in the HERCULES catalogue. This will be a key component in the continued development of models relating to the processes within γ Doradus stars.