Skip to main content Accessibility help
×
Home

The Three-Dimensional Structure of EUV Accretion Regions of AM Her Stars: Analysis of EUVE Light Curves

  • Martin M. Sirk (a1) and Steve B. Howell (a2)

Abstract

We present EUV light curves for a number of AM Her systems observed either as guest observer targets or with the EUVE Right Angle Program. We have formed light curves for eight AM Her stars and show in our presentation the similarities and differences present. We draw some conclusions by grouping the systems by inclination, magnetic field strength, and accretion region geometry. In order to understand the physical structures responsible for the EUV emissions, we have developed a software model to generate synthetic light curves. We find that the EUV accretion regions in the systems UZ For, VV Pup, and AM Her cannot be fit with a flat spot confined to the white dwarf surface, regardless of its shape or brightness profile. Rather, a small, symmetric, raised spot is the only shape consistent with the data. The light curves for systems EF Eri, RE1149+28, AN UMa, and V834 Cen show evidence for additional structure that precedes the primary accretion region in phase. Our model indicates that a large portion of the light curve in each system is seen in absorption. Finally, in three systems, we detect a very gradual rise and fall in the EUV flux (<5% of the peak flux) at phases when the spot is completely obscured behind the white dwarf (WD) limb. We attribute this detection to emission from the accretion column that decreases exponentially with distance from the WD and detect emission at heights up to 15% of the WD radius.

    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      The Three-Dimensional Structure of EUV Accretion Regions of AM Her Stars: Analysis of EUVE Light Curves
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      The Three-Dimensional Structure of EUV Accretion Regions of AM Her Stars: Analysis of EUVE Light Curves
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      The Three-Dimensional Structure of EUV Accretion Regions of AM Her Stars: Analysis of EUVE Light Curves
      Available formats
      ×

Copyright

References

Hide All
Bailey, J. & Cropper, M.S. 1991, MNRAS, 253, 27
Bowyer, S. & Malina, R.F. 1991, in Extreme Ultraviolet Astronomy, ed. Malina, R.F. & Bowyer, S., New York: Pergamon Press, 397
Cropper, M.S. 1990, Space Sci. Rev., 54, 195
Howell, S.B., Sir, M.M., Malina, R.F., Mittaz, J.P.D., & Mason, K.O. 1995, ApJ, 439, 991
Liebert, J. & Stockman, H.S. 1985, in Cataclysmic Variables and Low-Mass X-ray Binaries, Ed. Lamb, D.Q. & Patterson, J., Dordrecht: Reidel, 151
Malina, R.F., et al. 1994, AJ, 107, 751
McDonald, K., et al. 1995, AJ, 108, 5
Vennes, S., Szkody, P., Sion, E.M., & Long, K.S. 1995, ApJ, 445, 921
Warren, J.K., Sirk, M.M., & Vallerga, J.V. 1995, ApJ, 445, 909

Related content

Powered by UNSILO

The Three-Dimensional Structure of EUV Accretion Regions of AM Her Stars: Analysis of EUVE Light Curves

  • Martin M. Sirk (a1) and Steve B. Howell (a2)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.