Update on Binary central stars (with an eye on...
Transcript of Update on Binary central stars (with an eye on...
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