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Title:
A Multiwavelength Study of Spectral Variations in the CX Draconis Binary
Authors:
Richards, Mercedes T.; Koubský, Pavel; Šimon, Vojtěch; Peters, Geraldine J.; Hirata, Ryuko; Škoda, Petr; Masuda, Seiji
Affiliation:
AA(Department of Astronomy, University of Virginia, Charlottesville, VA 22903; .; Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatories. NOAO is operated by AURA, Inc. under contract to the National Science Foundation), AB(Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatories. NOAO is operated by AURA, Inc. under contract to the National Science Foundation.; Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic; ), AC(Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic; ), AD(Visiting Astronomer, Kitt Peak National Observatory, National Optical Astronomy Observatories. NOAO is operated by AURA, Inc. under contract to the National Science Foundation.; Space Sciences Center, University of Southern California, Los Angeles, CA 90089-1341 ), AE(Department of Astronomy, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; ), AF(Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic; ), AG(Department of Astronomy, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; )
Publication:
The Astrophysical Journal, Volume 531, Issue 2, pp. 1003-1027. (ApJ Homepage)
Publication Date:
03/2000
Origin:
UCP
ApJ Keywords:
ACCRETION, ACCRETION DISKS, STARS: BINARIES: CLOSE, STARS: CIRCUMSTELLAR MATTER, STARS: EMISSION-LINE, BE, STARS: INDIVIDUAL (CX DRA)
DOI:
10.1086/308491
Bibliographic Code:
2000ApJ...531.1003R

Abstract

An extensive collection of spectroscopic observations of the interacting binary CX Dra spanning a 23 year interval have been analyzed. This study includes a refinement of the orbital solution of CX Dra; equivalent width measurements that show short-, medium-, and long-term behavior of the difference profiles; a calculation of the Balmer decrement; velocity maps based on the velocity curves of the Hα and He I difference emission peaks; trailed spectrograms of the Hα, Hβ, He I, and Si II lines; and Doppler tomograms at these four wavelengths. The main conclusions are: 1. The circumstellar environment in the system changes in cycles of hundreds of days. The length of the cycles is variable. These cycles may be part of a ``super'' 4000 day cycle. 2. The equivalent widths of the difference Hα and He I λ6678 lines are modulated with the orbital period of 6.696 days. The corresponding phase diagrams indicate a great deal of scatter, but the modulation is quite conspicuous when long data strings are used. The pattern of the phase diagram suggests a permanent presence of the emission in Hα, He I λ6678, and Si II λ6371 lines. 3. The radial velocities of the Hα emission peak follow an S-wave. The resulting velocity map shows that the source of the single-peaked emission lies close to the L1 point, roughly between the primary and L1 point. 4. Doppler tomograms constructed for Hα observed and difference profiles show that the emission comes from a region of low velocity, a gas stream, and an accretion disk. The Hβ emission arises from a region that is cospatial with the Hα source. The Doppler tomograms for He I λ6678 and Si II λ6371 lines suggest that emission in this gas also originates from a locus of a disk around the primary star. 5. The model based on the equivalent widths of the difference profiles, the trailed spectrograms, and Doppler tomograms of the Hα, He I λ6678, Si II λ6371, and Hβ lines suggests that the main source of the Hα emission is about halfway between the stars at a distance of 0.49a from the primary star, and that the He I and Si II emission sources arise from an accretion disk centered on the primary star.
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