Novae
Dwarf Novae
Intermediate Polars
Polars
| Cataclysmic Variables | |||||
|
|
|||||
|
|
Novae |
Dwarf Novae |
Intermediate Polars |
Polars |
|
|
|
| Cataclysmic Variables (CVs) are a diverse class of short-period semi-detached binaries consisting of an accreting white dwarf primary and (typically) a low-mass main-sequence secondary star. The orbital periods of CVs typically range from approximately 0.6 day (14 hr) to 0.06 day (90 min). | |
| These binaries are quite small by astronomical standards: the binary separation is 1.1 (Porb/3 hr)2/3 (M1+M2)1/3 times the Sun's radius of 0.7 x 106 km (where Porb is the binary orbital period in hours and M1+M2 is the total mass of the binary in solar masses). | |
| The orbital evolution of these binaries, and hence the mass-transfer rate (Mdot) from the secondary to the white dwarf is driven by magnetic braking of the secondary for long-period systems (Porb > 3 hr) and gravitational radiation for short-period systems (Porb < 2 hr). | |
| The luminosity of CVs (like all compact binaries) is dominated by accretion: L = GMdotM1/R1 ~ 2.2 (Mdot/10-9 Msun/yr) (M1/Msun) (R1/104 km)-1 times the Sun's luminosity of 4 x 1033 erg/s (where Mdot is the mass-accretion rate in solar masses per year, M1 is the white dwarf mass in solar masses, and R1 is the white dwarf radius in km). | |
| CVs radiate primarily in the ultraviolet through X-ray bandpasses, hence are studied extensively with space-based telescopes such as the Hubble Space Telescope (HST), the Hopkins Ultraviolet Telescope (HUT), ORFEUS, the Far-Ultraviolet Explorer (FUSE), the Extreme Ultraviolet Explorer (EUVE), ROSAT, ASCA, the Rossi X-ray Timing Explorer (RXTE), the Chandra X-ray Observatory, and the XMM-Newton X-ray Observatory. | |
| With the nearest systems at distances of ~ 100 parsecs (300 light years) from Earth, the space density of CVs is moderately large (few x 10-5 parsec-3) and the total number in the Galaxy is huge (~ 106). | |
|
|
|
| Many of the images included in this group of webpages are the creation of Mark A. Garlick and are copyrighted by him. Their unauthorized usage is strictly forbidden. Please contact the artist personally if you require usage. | |
|
|
|||||
| Novae | CV Subtypes | Non-Magnetic CVs | Intermediate Polars | Polars | |
|
|
|||||
|
|||||
|
|||||
| Last modified May 30, 2003 | |||||
| UCRL-MI-135159 | |||||