The 67-min X-ray period of EX Hydrae observed with the EINSTEIN Observatory.
Abstract
The cataclysmic variable EX Hydrae has been observed in X-rays with the high resolution imager (HRI), IPC, and monitor proportional counter (MPC) of the Einstein observatory on two occasions. The X-ray spectra indicate multiple spectral components. A constant hard X-ray flux is found in the high-energy channels of the MPC. In the lower energy channels of the MPC and in the IPC a variable softer component is observed with a period of 67 min. The modulation is approximately in phase with the stable 67-min modulation in the optical brightness. The IPC X-ray spectrum changes slightly with the 67 min phase. The X-ray observations of EX Hya, recently interpreted as an intermediate polar, exhibit many features characteristic of AM Her-type stars. The constant hard X-ray source, e.g., is expected from an AM Her-type star with suitable orientation of the magnetic axis with respect to the inclination angle. The AM Her-type X-ray properties of EX Hya and the possible absence of a standard accretion disk in the system are discussed.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 1987
- Bibcode:
- 1987A&A...183...73H
- Keywords:
-
- Accretion Disks;
- Cataclysmic Variables;
- Heao 2;
- Light Curve;
- Stellar Mass Accretion;
- X Ray Astronomy;
- Astronomical Photometry;
- Eclipsing Binary Stars;
- Novae;
- Visible Spectrum;
- White Dwarf Stars;
- Astrophysics