Basics of Cataclysmic Variables iPTF Summer School August 28, 2014 Paula Szkody U of Washington

A Cataclysmic Variable : is a close binary system has a white dwarf primary has a cool low mass secondary actively transfers mass

Types of cataclysmic variables: [Nova] Dwarf nova ( U Gem, Z Cam, SU UMa, WZ Sge, ER UMa ) Novalike ( UX UMa, SW Sex, V Sge, Polar, IP ) AM CVn [Type Ia SN, Symbiotic star]

DISK ACCRETION MAGNETIC High MLow M.. X-rays 10 8 K K ACCRETION BL For slowly rotating WD: L disk = L BL = 1/2GMM wd /R wd. Hard X-rays Soft X-rays Cyclotron

Disk System Polar Intermediate Polar LARP CV Types Steve Howell

common envelope Possible evolution paths phas e Angular momentum losses Pre-CV

Model of CV Population Howell, Nelson, Rappaport 2001, ApJ, 550 Log number of CVs Population models PG, Hamburg SDSS. Magnetic braking g radiation Where are detached magnetic WDs + M stars?

CVs mostly blue but color range too wide to find objects -- need color + variability + spectra to find true populations SDSS showed:

CVs in SDSS Szkody et al. AJ Papers I-VIII Need lots of follow-up spectra for ID and properties! What we learned from SDSS:

Summary of Variability and timescales for Interacting Binaries

Science from DN Outbursts Long term heating of WD Mass accreted Irradiation of secondary Disk heating and cooling

AAVSO outbursts of SS Cygni Dwarf novae Repeated disk instability.

Z Cam system standstills

July 23 Short Porb, Low M outburst ~ 1/20 yrs.

AAVSO data plotted by Matt Templeton Apr12 07 GW Lib 2007outburst: amp ~ 9 mag 27 days Return to quiescence at V=17 > 4 yrs

V1159 Ori ER UMA Type Supercycles

Superhumps at SOB ApJ, 1984, 282, 236

MRO NOFS Tramposch et al. 2005, PASP 117, 262 P= 1.9 hr Positive SH Negative SH

quiescence outburst rise

Novalike systems with periods of 3-4 hrs Honeycutt & Kafka, 2004, AJ, 128, 1279 Low states

Honeycutt, Turner & Adams 2003 Roboscope Totally Unknown: Long term variability

2 like this now known SDSS1238 : Phot P: min Spect P: 80.5 min Long P: hrs

Science from Orbital variations Eclipsing systems enable photometric model Can detect eclipse of disk, hot spot, WD Can parameterize accretion area in magnetic systems P orb ( hrs) allows population, evolution study Requires high time resolution (eclipses <15 min) ~30% of disk systems show orbital variations (spot); 100% of polars (amplitudes of mags)

NOFS P=3.96hr Eclipsing systems- WD goes behind M star P=2.4hr Hot spot

USN O Eclipse of accretion column by M star Polar

SDSS KPNO 2.1m 2011

PTF candidate magnetics (Margon, Levitan,Prince, Hallinan 2013 ASPCS)

Wickramasinghe & Ferrario 2000, PASP B=30 MG Theta= 90 deg higher opt depth

TiO cyclotron harmonics Szkody et al. ApJ, 583, 902, 2003 WD Temp = K 7/9 LARPs found in SDSS B ~ 60 MG T < 1keV M~ M /yr P=4.4 hrs D=100pc. 34 MQ Dra

Typical LARP B=60 MG, Mdot = solar mass/yr ApJ, 683, 967, 2008

Cyclotron harmonics result in strange colors Finding LARPs is not easy -

Low Accretion Rate Polars as a function of magnetic field Schmidt et al. 2005, ApJ, 630, 1037

Science from Pulsations, Spins 16 White Dwarfs in Instability Strip Periods about 2-20 min Amplitudes < 0.1 mag Gives info about WD interior Pulsations Spins Magnetic White Dwarfs Periods min (IP), hrs (polars) Amplitudes mag Gives info on magnetic field

White dwarfs show non-radial g-modes on account of their high gravity Periods of 100s to 1000s These modes are characterized by quantum numbers (k,l,m) similar to atomic orbitals Spherical gravitational potential  Spherical electrostatic potential l determines the number of borders between hot and cool zones on the surface m is the number of borders that pass through the pole of the rotation axis k determines the number of times the pulsation wiggles from the center to the surface

Light curves & DFTs of accreting pulsator SDSS SDSS finds 9/16 accreting pulsators Mukadam et al AJ

SH pulse

FO Aqr Patterson et al PASP P spin = 21 min Spin from Intermediate Polar

Science from Flickering Signature of active accretion (blobs?) Timescales of sec (Polars) Timescales of min (disk) Origin from spot, column or inner disk

Novalike LS Peg Recurrent nova (Dobratka et al. 2010) Flickering Examples

What we learn from CV variability : flickering - info on accreting blobs pulsations - info on interior of WD, instability strip for accretors spin timescale of WD - info on mag field orbital variations - info on WD, spot, evolution outbursts - info on long term heating

Examples from CSS

~1000 potential CVs in CRTS (Drake et al.; Breedt et al MNRAS) Only ~200 confirmed by spectra Most are short P (low M transfer) Most are dwarf novae Most in thick disk

unpredictability of CVs! Observe and enjoy the