1. An ancient nova shell around the dwarf nova Z Camelopardalis Michael M. Shara, et al. 2007, Nature, Vol. 446 8 March 鹿豹星座

2. Contents Cataclysmic variables [Classical nova (nova) and Dwarf nova] GALEX observation around the dwarf nova Z Cam (Camelopardalis) Connection classical nova and Dwarf nova

3. Classical Nova (L~10 5 L sun ) The classical nova outburst arises from a nuclear explosion in the surface layers of a white dwarf When about 10 -4 M sun of of hydrogen-rich matter has been accreted from the companion (red- dwarf), temperature and the density is enough large so that a nuclear explosion. Typical time intervals between outbursts are several ten thousand years. Typical time intervals between outbursts are several ten thousand years.

4. Dwarf Nova The matter accumulates in the accretion disk until an instability develops The entire accretion disk crashes down onto the white dwarf and large amounts of gravitational energy are released. Within weeks to months, a new accretion disk forms, becomes unstable, and the outburst is repeated. Within weeks to months, a new accretion disk forms, becomes unstable, and the outburst is repeated.

5. A prediction including all dwarf novae a classical nova. The accretion of a sufficiently massive shell onto a white dwarf in any cataclysmic binary, including all dwarf novae, is predicted to inevitably generate pressures large enough to initiate a thermonuclear runaway and hence a classical nova. (Shara, M.M.A., 1981)

6. Z Camelopardalis (Z Cam) Z Cam is one of the brightest and of the closest (~163 pc) dwarf novae in the sky.

7. NASA UV telescope GALAX observed Z Cam and its surroundings GALAX revealed, for the first time, an arc UV-emitting material with a radius r~15 arcmin (SW), and linear nebulosities (NE and SE) This nebulosities material are interpreted as the ejecta produced by historical classical nova.

8. Spectroscopic observations HαHα [N ‖ ] [O ‖ ]

9. Shocked ionized shell Density of the Shell →, wheres is expected from the conventional theory. Shock thickness → arcmin Total mass of the shell →

10. Classical nova origin? If the classical nova origin, the most contribution on the mass of shell must be the gathered ISM. →Nova model predicts an ejected envelope for 1 solar mass white dwarf. ● The observed range of the velocity of the matter recently appeared novae is which gives an age of the shell, ● If real age is >1000, there would be no historical record. ● This young age also is consistent with the present location of Z cam with the proper motion.

12. Others ? 1.Wind ejected from the Z Cam system during the dwarf nova ? 1.A remnant planetary nebula ejected by AGB star, which is now white dwarf ? Mass loss rate Expected age of the shell Displacement due to its proper motion

13. including all dwarf novae a classical nova. The accretion of a sufficiently massive shell onto a white dwarf in any cataclysmic binary, including all dwarf novae, is predicted to inevitably generate pressures large enough to initiate a thermonuclear runaway and hence a classical nova. (Shara, M.M.A., 1981)