Metallic line doubling in the spectra of the variable RR Lyrae star

Frontiers in Theoretical and Applied Physics/UAE 2017

Sefyani, F.L.^1 ; Benhida, A.^1 ; Benkhaldoun, Z.^2 ; De France, T.^3 ; Gillet, D.^4 ; Mathias, P.^5 ; Lazrek, M.^2 ; Eljariri, Y.^2 ; Chafouai, K.^2 ; Daassou, A.^2

Oukaimeden Observatory, LPHEA FSTG, Cadi Ayyad University, BP 549, Marrakech, Morocco^1

Oukaimeden Observatory, LPHEA FSSM, Cadi Ayyad University, BP 2390, Marrakech, Morocco^2

AAVSO (American Association of Variable Star Observers), 49 Bay State Rd, Cambridge

MA, United States^3

Observatoire de Haute-Provence, CNRS/PYTHEAS/Université d'Aix-Marseille, Saint Michel l'Observatoire

04870, France^4

CNRS UMR5277 Institut de Recherche en Astrophysique et Planétologie, 14 Avenue Edouard Belin, Toulouse

31400, France^5

关键词: Absorption lines;    Expansion phase;    High intensity;    Hydrogen lines;    RR Lyrae stars;    Spectral components;    Two-layer atmospheres;    Variable stars;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/869/1/012088/pdf
DOI  :  10.1088/1742-6596/869/1/012088

来源: IOP

【 摘 要 】

We present the observation of line doubling absorption in the spectra of the RR Lyrae variable star on the metal lines of FeII (λ = 4923.921Å) as well as of D1 and D2 lines of sodium. For the emission, we observed the lines of hydrogen Hαand Hβwith a very high intensity and the two lines of HeI (λ = 5875.66 Å and λ = 6678.15Å). This transmission/helium I remission [1, 2] is directly related to the intensity of the shock wave through the atmosphere of the star during the phase of maximum Blazhko cycle [3]. During the expansion phase of the photosphere of the star and during the passage of the shock wave we witnessed a disappearance of the absorption lines of neutral FeI (λ = 4934.006Å and λ = 4920.503Å) and their reappearance in phase 1.00. These observations were made with a spectrograph resolution scale of about 12,000 installed on the C14 telescope at the Oukaimeden observatory (J43) during the different star pulsation cycle. We noticed that some of them almost coincide with the maximum Blazhko cycle. The doubling line were interpreted by Schwarzschild [4] on the basis of a two-layer atmosphere. This interpretation could measure the speed of the shock wave derived from the difference between the two red and blue spectral components on Hαhydrogen lines, D3 helium, D1 and D2 lines of sodium and FeII during the observed doubling of lines. At phase 1.00, the shock wave reached the maximum speed of 160 km.s-1confirming the hypersonic regime occur during this maximum Blazhko cycle.