Brent Miszalski (SAAO/SALT) Henri Boffin & Dave Jones (ESO),

Romano Corradi & Pablo Rodríguez-Gil (IAC),

Miguel Santander-García (OAN)

Update on Binary central stars

(with an eye on ChanPlaNS)

How to find binaries

• Direct imaging: limited to wide systems. No P

determination, but >102 years.

• Light curves: irradiation, ellipsoidal variations (contact

or semi-detached binaries), eclipses. P≤ a few days

• Radial velocity curves. P≤ few102 days

• Spectroscopic or photometric detection of “cool” (=not

hot enough) companions. No P.

Close binaries (firm)

Single (?) stars Some objects probably just single stars with X-rays generated in

clumpy winds (e.g. NGC6543) - work by Guerrero/De Marco

• NGC4361:

• 3xSALT spectra --> no big shifts

• Flat SAAO lightcurve

Some others could be mergers

• IC4663: [WN3] CSPN, He-rich (95%) atmosphere (Miszalski+ 2012)

• (V)LTP scenarios CANNOT explain He-rich composition

• 3 epochs show no RV variability

• WD+WD merger best scenario (Reindl+ 2013; Miszalski+2013)

Would a WD+WD merger product show a (spun-up?) CSPN with X-ray

signature?

IC4663

Miszalski+2012

Double degenerates

• A41 (Shimanskii et al. 2008)

• PN G135.9+55.9 (TS01, Tovmassian et al. 2010)

• V458Vul (Nova Vul 2007, Rodriguez et al. 2008)

• NGC6026 (Hillwig et al. 2010)

• Fg1 (Boffin et al. 2012)

• Hen 2-428 (Santander et al. 2013)

Double degenerates

• TS01: Hot component Teff = 160–180 kK, a luminosity of about ∼104

L. Probably bloated and heated as a result of intense accretion and

nuclear burning on its surface in the past. Cool component has Teff =

60kK.

• Ellipsoidal variation + flickering accretion.Total mass of the binary

system is close to the Chandrasekhar limit SNIa candidate

Fleming1 Boffin et al. 2012, Science, 338, 773

Fleming1

VLT FORS

radial velocity

curve

Flat lightcurve

Boffin et al. 2012, Science, 338, 773

Need RV

monitoring to

find DDs!

long assumed binary

now proven!

Envelope from shocked jets as

first predicted by Cliffe et al.

Raga+

2009

Cliffe+ 1995, 1996 Raga+ 2009 Boffin+ 2012

Fleming1: binary shaped jets

Hen 2-428

Santander-García et al. , in preparation

dense circumstellar medium (ne=103.3-

6 cm-3) + zone with ne>1010 cm-3 (from

Ca II triplet in emission) accretion

disc?

P=4 hours, ellipsoidal variations

2 contact-WDs?

V458 Vul: Nova Vul 2007

Wesson et al. 2008, ApJ 688, L21

Rodriguez-Gil et al. 2010, MNRAS 407, L21

P=98 min

V458 Vul

A nova with such a short period MUST be an old system, MUCH

older than the 14000 yr old PN

the PN is the SECOND one of the system (after a 2nd common-

envelope stage)

2 WDs, M = 0.58M (photoionisation model) and M > 1M (nova

theory) Mtotal > 1.6 M > MChandrasekhar V458 Vul is another

SN Ia candidate

(GK Per (Nova Per 1901) might be another case of a nova inside a PN)

Accretion in CSPN?

• Except for TS01, V458 Vul and possibly Hen 2-428, in

general we see no evidence for active accretion on the hot

central star in PNe. Almost all post-CE systems are

detached

• Therefore, it is possible some post-CE nuclei may emerge

from CE phase semi-detached/interacting at lower end of

period distribution

Wind Accretion (on secondaries)

• Formation scenario: Polluted material accreted via wind

accretion (e.g. Wind RLOF) from WD progenitor during

its AGB phase

• Barium CSPN: S-process and carbon enriched

(sub)giants with evolved WD companions

• Carbon dwarfs: enriched by PN progenitors in their

carbon star AGB phase

• PNe provide the best evidence: as they catch the

systems right after the “main act”.

Wind Accretion on secondaries

• Bona-fide barium CSPN: LoTr5, A70, WeBo1

• Accretion spins up red giant => Fast rotation velocity (near

break up) and...

• sometimes X-rays - LoTr 5 (Montez et al. 2010)

• Some ChanPlaNS detections suspected:

• NGC7008 and NGC6445 (need follow-up)

• Also happens in post-CE systems

• The Necklace (Miszalski, Boffin & Corradi 2013)

• Might explain „bloated‟ secondaries in post-CE systems

White Dwarf

V~20.4 mag

GALEX

G8IV-V

V~17.8 mag

GMOS

SED Abell 70 Miszalski+ 2012

WeBo 1 Bond+2003

WeBo1 WD

detected by

SWIFT/UVOT

Siegel+ 2012

(Not detected

in Swift X-ray

observations)

WeBo1 analogue found in South by SALT

(Miszalski+2013 to be submitted soon)

The Necklace Corradi+ 2011

Miszalski, Boffin & Corradi 2013

Carbon dwarf + preWD

•Accretion BEFORE

CE phase C/O>1

•Consistent with jet

dynamic age (pre-PN)

Jet formation in PNe

• In past, jets have mostly been studied in pre-PNe, but binary

status of pre-PNe poorly understood

• Several post-CE PNe are known to have jets

• Not highly collimated => precession influenced

• Most post-CE PNe have jets ejected before main nebula (CE)

• Thought to launch from accretion disk around companion PRIOR

to (very short) CE phase (e.g. Huarte-Espinosa+2013)

• Observational evidence only now available to demonstrate this is

the case for most systems. Necklace best example.

ETHOS1

Mis

zals

ki+

20

11

(Romano‟s) summary Increasing evidence for post-CE binaries in CSPNe. Total fraction still

undetermined, but ≥20%

Clear relation between (CE) binarity and some morphological features,

mainly rings and jets. Mild (broad-waist) bipolars also frequently found.

But a variety of other morphologies also found.

Still no direct evidence for binarity in the most classical (narrow-waist)

bipolars like NGC6302, NGC6537, MyCn18, M2-9, Mz 3, etc. Long period

binaries? RV programme ongoing, results at APN6.

A lot of new evidence of pre-CE accretion onto secondaries barium stars,

carbon dwarfs. This is now assumed to be the cause of pre-CE jets.

Some systems (6 out of 40) double degenerates. Some are good SNIa

progenitors.

Binary CSPN with X-ray detection need dedicated study. For several of them,

little is known about the basic binary parameters.

Thanks for listening!

SALT HRS

Durham Centre for

Advanced

Instrumentation

• High Resolution Spectrograph to arrive mid-2013 at SALT -

ideal for relatively bright CSPN at δ<11.25°

• Fibre fed, temperature stabilized vacuum tank design

• Three modes: R=16 000, 37 000 and 65 000

• Wavelength range: 380-890 nm over two CCDs

• CHANPLANS sample: RV monitoring and high quality spectra

for model atmosphere fitting