EX Hydrae

EX Hydrae

EX Hydrae is a southern variable star classified as an eclipsing intermediate polar-type cataclysmic variable(CV). EX Hya is a binary system with an orbital period of 98 minutes and belongs to a small group of polars with ultrashort periods. This variable also has a 67-minute oscillation believed to be the spin period of the white dwarf component.  Outbursts of EX Hya are generally recurring every two years or so with a magnitude range of 13.5 to 9.2. EX Hya is also a source of hard and soft X-rays.

There are over 32,000 observations of EX Hya in the AAVSO International Database dating back to 1954. Outbursts are relatively quick rising about 2-3 magnitudes and lasting only a few days. At least 15 outbursts have been detected in the past 50 years.

The long-term light curve of EX Hya from the AAVSO database also highlighting my observations (SRX) from when I first started to observe EX Hya.

In August 1998 I detected an outburst of EX Hya at 9.5. This lead to the first-ever satellite observations in X-rays, by the Rossi X-ray Timing Explorer.  A light curve of my observations of EX Hya showing outburst detections up to  September 2012.

Co-Authored paper on EX Hya.

Outbursts of EX Hydrae: mass-transfer events or disc instabilities? 2000MNRAS.313..70H

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