the sw sextantis stars and the evolution of cataclysmic variables pablo rodríguez gil 5 january...
TRANSCRIPT
![Page 1: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/1.jpg)
The SW Sextantis starsand the
evolution ofcataclysmic variables
Pablo Rodríguez Gil
5 January 2006
![Page 2: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/2.jpg)
Summary
Introduction.
Cataclysmic variable structure and evolution.
The SW Sextantis stars: new insights on their accretion structure.
Towards a global understanding.
The HQS and SDSS and CV evolution.
![Page 3: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/3.jpg)
Astrophysical context
Most of the stars are born in binary or multiple systems.
~50% of the binaries will interact at some point (Iben 1991).
Many exotic astrophysical objects (e.g. binary pulsars, black holes, LMXBs, symbiotics…) are descendent from binary systems.
Type Ia supernovae: accretion on to white dwarfs. Cosmological distance scale.
![Page 4: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/4.jpg)
Compact binaries
They harbour a compact stellar remnant (i.e. WD, NS or BH).
Their evolution critically depends on the angular momentum loss rate (dJ/dt).
t Detached binary
Common envelope
AML; a decreases
Envelope ejection
AML: magnetic braking or gravitational radiation
Contact
![Page 5: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/5.jpg)
Summary
Introduction.
Cataclysmic variable structure and evolution.
The SW Sextantis stars: new insights on their accretion structure.
Towards a global understanding.
The HQS and SDSS and CV evolution.
![Page 6: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/6.jpg)
What is a cataclysmic variable?
Donor star
Bright spot
White dwarf
Gas stream
Accretion disc
~ Main sequence
Secondary star
Late type (K-M)
M2~ 0.05-1 M
White dwarf
Primary component
<M1> ~ 0.7 M
![Page 7: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/7.jpg)
CVs have magnetic fields…
![Page 8: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/8.jpg)
…accretion discs…
![Page 9: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/9.jpg)
…or both!
![Page 10: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/10.jpg)
The intermediate polar CVs
![Page 11: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/11.jpg)
The height of the shock front depends on the cooling mechanisms in the column.
The emission spectrum of the column:
108 K
105 K
Bremsstrahlung: Hard X rays (kTbr ~ 30 keV)
Compton: UV and soft X rays (kTBB ~ 40 eV)
Cyclotron: IR-optical-UV (POLARISED)
Magnetic accretion
![Page 12: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/12.jpg)
Orbital period distribution
Ritter & Kolb (2003): 496 systems
Gives observational input on the AML rate
![Page 13: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/13.jpg)
Flashback – 1983: ‘Disrupted magnetic braking’
Paczynski & Sienkiewicz; Spruit & Ritter; Rappaport et al. (1983)
Two AML mechanisms:
Magnetic braking (stellar wind) & gravitational radiation
MB+GR GR
![Page 14: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/14.jpg)
Standard theory predictions
- Paucity of the number of CVs in the range Porb=2-3 hr
![Page 15: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/15.jpg)
The ‘period gap’
![Page 16: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/16.jpg)
Standard theory predictions
- Minimum Porb of ~ 65 min
- Paucity of the number of CVs in the range Porb=2-3 hr
![Page 17: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/17.jpg)
The minimum orbital period
~80 min!
![Page 18: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/18.jpg)
Standard theory predictions
- Minimum Porb of ~ 65 min X
- Paucity of the number of CVs in the range Porb=2-3 hr
- Pile-up of systems at Pmin
![Page 19: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/19.jpg)
Population syntheses: the minimum period
Kolb & Baraffe (1999)
![Page 20: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/20.jpg)
The minimum orbital period
~80 min!
![Page 21: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/21.jpg)
Standard theory predictions
- Minimum Porb of ~ 65 min X
- Paucity of the number of CVs in the range Porb=2-3 hr
- 99% of all CVs should have Porb < 2 hr
- Pile-up of systems at Pmin X
![Page 22: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/22.jpg)
Orbital period distribution
191=38%250=51%
55=11%
![Page 23: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/23.jpg)
Standard theory predictions
- Minimum Porb of ~ 65 min X
- Paucity of the number of CVs in the range Porb=2-3 hr
- Pile-up of systems at Pmin X
- 99% of all CVs should have Porb < 2 hr X
![Page 24: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/24.jpg)
Standard theory predictions
- Minimum Porb of ~ 65 min X
- Paucity of the number of CVs in the range Porb=2-3 hr
- Pile-up of systems at Pmin X
- 99% of all CVs should have Porb < 2 hr X
- CV density ~
Observed ~ X
We are in deep trouble!
![Page 25: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/25.jpg)
An alternative AML prescription
Verbunt & Zwaan (1981) vs. Sills et al. (2000).
Nevertheless, something is happening above the gap……………
![Page 26: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/26.jpg)
Summary
Introduction.
Cataclysmic variable structure and evolution.
The SW Sextantis stars: new insights on their accretion structure.
Towards a global understanding.
The HQS and SDSS and CV evolution.
![Page 27: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/27.jpg)
The SW Sextantis stars
- Unusual spectral features, inconsistent with a standardoptically thick, geometrically thin accretion disc.
- Extremely high mass accretion rates.
- ~50% of all CVs in the 3-4 hr strip are SW Sextantis stars.
- No place for such maverick systems in the standardevolution theory.
![Page 28: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/28.jpg)
Trailed spectra. Pulsed S-wave (Rodríguez-Gil et al. 2001)
LS Pegasi
Pulse separation
~ 0.1 Porb
A likely magnetic nature
![Page 29: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/29.jpg)
A likely magnetic nature
V533 Her (Rodríguez-Gil & Martínez-Pais 2002)
DW UMa (Smith et al., unpublished)
- Emission-line flaring also characteristic of IPs.
![Page 30: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/30.jpg)
PEW = 33.5 2.2 min
A likely magnetic nature
LS Pegasi
![Page 31: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/31.jpg)
Circularly polarised continuum.
P1 = 29.6 1.8 min
1/ P1 - 1/PEW = 1/Porb
(PEW synodic period)
Cyclotron radiation
B1 ~ 10 MG
A likely magnetic nature
LS Pegasi
(Rodríguez-Gil et al. 2001)
![Page 32: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/32.jpg)
Strong HeII 4686 emission, typical of mCVs.
A likely magnetic nature
RX J1643.7+3402
(Martínez-Pais, de la Cruz & Rodríguez-Gil, submitted)
![Page 33: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/33.jpg)
Discovery of circular polarisation.
P1 = 19.4 min
RX J1643.7+3402
(Martínez-Pais, de la Cruz & Rodríguez-Gil, submitted)
A likely magnetic nature
![Page 34: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/34.jpg)
Variable HeII 4686 EW.
P =25.5 min (coherent for at least 15 cycles).
V1315 Aql
A likely magnetic nature
![Page 35: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/35.jpg)
Light curve oscillations (QPOs).HS 0728+6738
A likely magnetic nature
![Page 36: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/36.jpg)
Summary
Introduction.
Cataclysmic variable structure and evolution.
The SW Sextantis stars: new insights on their accretion structure.
Towards a global understanding.
The HQS and SDSS and CV evolution.
![Page 37: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/37.jpg)
Magnetism and CV evolution
- Magnetic fields can play a crucial role in CV evolution.
- At least half the CVs in the 3-4 h range can be magnetic(only 3% of isolated WDs are!).
A comprehensive study of the SW Sextantis stars is therefore mandatory.
1) Masses involved.
2) Search for more systems.
3) Circular polarimetry.
![Page 38: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/38.jpg)
Weighing the components
- SW Sextantis stars ocassionally fade. ’LOW STATES’.
- The absence of DN-type outbursts during the low statessupports a magnetic scenario (Hameury & Lasota 2002).
(Honeycutt & Kafka 2004)
![Page 39: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/39.jpg)
Weighing the components
- Photometric monitoring campaigns in the North and South.
- ToO programmes at the VLT, and the WHT and NOT.
HS 0220+0603
Sp(2)=dM3-4 V
T1 > 25000 K
d ~ 0.7-1.0 kpc
VLT
![Page 40: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/40.jpg)
Weighing the components
- First donor star radial velocity curve at the WHT (R = 19.4).
HS 0220+0603
K2 = 330 km/s
i = 83º
M2 = 0.3 M
M1 = 1.0 M
![Page 41: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/41.jpg)
Weighing the components
- WD exceeds the average mass of 0.65 M.
- T1 is unusually high. DW UMa has ~ 50000 K.
- Secular heating of the WD. Why such a high transfer rate?
Fundamental to measure the physical parameters of a large sample of
systems!
![Page 42: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/42.jpg)
A growing family
- Search programmes in both hemispheres.Linda Schmidtobreick (ESO), Boris Gänsicke (Warwick, UK).
- Targets: CVs in the 3-4 h orbital period range. Asymmetric line profiles with enhanced wings. Short-time scale photometric variability (QPOs). Presence of the HeII 4686 line and Bowen. Low states. ...
- Preliminary results in the south show great success.
![Page 43: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/43.jpg)
A growing family
V380 Ophiuchi
NTT + WHT
P = 3.72 hr
![Page 44: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/44.jpg)
A growing family
AH Mensae
NTT
P = 2.97 hr
![Page 45: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/45.jpg)
Summary
Introduction.
Cataclysmic variable structure and evolution.
The SW Sextantis stars: new insights on their accretion structure.
Towards a global understanding.
The HQS and SDSS and CV evolution.
![Page 46: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/46.jpg)
The HQS and the SDSS
- The current CV population is a mixed bag (novae, DNoutbursts, rapid variablility, blue colour, X rays).
- Need for an UNBIASED CV sample.
- The HQS and the SDSS CVs are spectroscopically selected.
![Page 47: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/47.jpg)
The HQS: 53 new CVs, 35 Porb
SW Sextantis excess @ 215 min (20%)
![Page 48: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/48.jpg)
The HQS and the SDSS
- The current CV population is a mixed bag (novae, DNoutbursts, rapid variablility, blue colour, X-rays).
- Need for an UNBIASED CV sample.
- The HQS and the SDSS CVs are spectroscopically selected.
- The SDSS (g < 21) have provided ~120 new CVs.
![Page 49: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/49.jpg)
The SDSS: 120 new CVs, 45 Porb
![Page 50: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/50.jpg)
The HQS and the SDSS
- The current CV population is a mixed bag (novae, DNoutbursts, rapid variablility, blue colour, X-rays).
- Need for an UNBIASED CV sample.
- The HQS and the SDSS CVs are spectroscopically selected.
- The SDSS (g < 21) have provided ~120 new CVs.
The period distribution of the SDSS CVs will serve as afundamental test to the standard theory.
Major revision is expected…
![Page 51: The SW Sextantis stars and the evolution of cataclysmic variables Pablo Rodríguez Gil 5 January 2006](https://reader036.vdocuments.net/reader036/viewer/2022062409/56649ea95503460f94bae041/html5/thumbnails/51.jpg)
The SW Sextantis starsand the
evolution ofcataclysmic variables
Pablo Rodríguez Gil
5 January 2006