Abstract
view Abstract Citations (28) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Pulsational mode typing in line-profile variables. VI. Nonradial modes in the remarkable B star epsilon Persei. Smith, M. A. Abstract Epsilon Persei is a B0.7 III star with no radial velocity or photometric variations at optical wavelengths, but it shows such pronounced variations in line shape that it has been mistakenly classified as a double-lined spectroscopic binary. We have obtained nearly 200 high-quality charge-coupled device (CCD) observations of the Si III λ 4567 triplet on two pairs of nights separated by a month. It is possible to fit a representative sample of 40 of them with three prograde sectorial nonradial pulsation modes with degrees l = 6, 4, and 1 or 2. The observed frequencies appear to be in the ratio of 6:4:1 with σ6 ≍ 10.9 cycles day-1 The nonradial velocity amplitudes are greatest for the higher degree modes; the l = 6 mode velocity amplitude already rivals the atmospheric sound speed. On our two best-observed nights, the traveling waves do not appear to be uniformly spaced but rather show the greatest separation in arrival time when the modes constructively interfere. The effect is to "modulate the periods," and we tentatively ascribe this behavior to the nonlinearity caused by the high amplitudes. The periods in ∈ Per demonstrate that both p- and g-type modes can coexist in a B star. The apparent period commensurabilities in this star suggest that the exotic high-l modes observed are resonating "stray" modes with frequencies that are harmonics of a basic low-frequency g mode. The star ∈ Per appears to be a highly prominent example of a new sub-class of rapidly rotating variables discovered by Walker, Yang, and Fahlman and identified as nonradial pulsators by Vogt and Penrod and by Baade. Similarities and possible physical links between them and the 53 Persei and β Cephei variables are suggested. Publication: The Astrophysical Journal Pub Date: January 1985 DOI: 10.1086/162788 Bibcode: 1985ApJ...288..266S Keywords: B Stars; Line Shape; Stellar Oscillations; Stellar Spectrophotometry; Variable Stars; Vibration Mode; Algorithms; Charge Coupled Devices; Spectrum Analysis; Stellar Models; Stellar Rotation; Transient Response; Visible Spectrum; Astrophysics full text sources ADS | data products SIMBAD (3) Related Materials (6) Part 1: 1980ApJ...238..250C Part 2: 1980ApJ...238..667C Part 3: 1980ApJ...240..149S Part 4: 1982ApJ...254..242S Part 5: 1983ApJ...265..338S Part 7: 1986ApJ...304..728S
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