Doppler Tomography of Algols and RS CVns

Mercedes Richards

The tomograms of the Algol-type binaries display a diverse range of circumstellar structures that include a gas stream, accretion annulus, transient accretion disk, and/or chromospheric emission source in a short-period Algol, or a classical accretion disk in a long-period system. Some systems, like U CrB and U Sge, alternate between stream-like and disk-like states. So far, H-alpha tomograms have been made for 12 Algols, including the non-eclipsing system of CX Dra. Other tomograms of CX Dra were made from the observed and difference H-alpha, H-beta, He I (6678 Angs.), and Si II (6371 Angs.) profiles. An ultraviolet tomogram of U Sge has also been made from Si IV (1394 Angs.) difference profiles. Tomograms produced at multiple epochs demonstrate stability in systems like beta Per and TX UMa but variability in others like U Sge, U CrB, and CX Dra. Most of the tomograms of the short-period Algols were produced from difference spectra rather than the observed spectra because the nonphotospheric gas can best be studied if the contribution from the stars, the photospheric light, is subtracted from the observed spectrum.

An Algol-type binary:  

Highlights:

• 2009: 3D Tomograms of U CrB and RS Vul in 3D velocity cube format (Richards, Sharova & Agafonov, submitted to ApJ)
  
• 2009: 3D Tomography of Disk-like and Stream-like States of U CrB (Agafonov, Sharova & Richards 2009)
  
• 2006: First 3D Tomography of an Algol Binary: U CrB (Agafonov, Richards & Sharova 2006)
  
• 2006: Use of synthetic spectra to model the accretion structures in TT Hya (Miller, Budaj, Richards, Koubsky & Peters 2006)
  
• 2005: Application of the SHELLSPEC code to TT Hya (Budaj, Richards & Miller 2005)
• 2004: Development of the SHELLSPEC code (Budaj & Richards 2004)
• 2004: IAU General Assembly: JD9: Astrotomography - Summary of Algols (Richards 2004)
• 2001: Summary of tomography of the Algols (Richards 2001)
• 2000: 23-year multiwavelength study of CX Dra (Richards, Koubsky, Simon, Peters, Hirata, Skoda, & Masuda 2000)
  
  accretion disk, gas stream and hot spot imaged
• 1999: First ultraviolet tomogram of an Algol (U Sge) (Kempner & Richards 1999)
• 1998: Hydrodynamic simulations used to interpret Doppler tomograms (Richards & Ratliff 1998)
• 1996: Images of accretion disks (Albright & Richards 1996)
• 1996: Images of chromospheres (Richards & Albright 1996)
• 1995: The first images of gas streams (Richards, Albright & Bowles 1995)
• Some images are shown here:
  
  H-alpha tomograms of eclipsing Algols
  Multiwavelength tomograms of CX Dra, a non-eclipsing Algol
  H-alpha and Si IV tomograms of U Sge
  



• Movie showing changes in U CrB (1994) difference spectra around the orbit.




• List of published tomograms of Algols
  
• Understanding the Algols: Light curves, spectra, tomograms, and hydrodynamic simulations