a new review of old novae

7/27/2019 A New Review of Old Novae

http://slidepdf.com/reader/full/a-new-review-of-old-novae 1/59

A New Review of Old Novae

Ashley Pagnotta



Not necessarily quite this old…

Fontanille 2007

…but some are!

Judean coin depicting Nova 134 BC, also observed by Hipparchus.




What actually happensafter a nova eruption?




• Teruption + 0 years

• Teruption + 10 years• Teruption + 100 years






• Teruption + 10 years• Teruption + 100 years




First, the mass loss leads to an increase in theorbital separation of the two stars.

Shara et al. (1986)



Second, sustained nuclear burning on the surface of the white dwarf irradiates & puff s up the companion.

Garlick/space-art.co.uk



Is it a coincidence that these two eff ects cancel eachother out most of the time?

Collazzi et al. (2009)

Eruption

mpostmpre

Δm = mpre - mpost



Is it a coincidence that these two eff ects cancel eachother out most of the time?

For CNe Exclusively:

• 25 systems

• 25 eruptions

• Δmavg = +0.16 mag

• Δmmed = +0.13 mag

• σ = 0.42 mag

Including RNe:

• 31 systems

• 44 eruptions

• Δmavg = +0.03 mag

• Δmmed = +0.03 mag

• σ = 0.43 mag

Collazzi et al. (2009)

Both consistent with Δm ≈ 0!



But of course, there are a few weird systems thatrefuse to follow the rules.

Schaefer & Collazzi (2010)

Δm ≈ 4 mag



But of course, there are a few weird systems thatrefuse to follow the rules.

Schaefer & Collazzi (2010)

Δm ≥ 5 mag



The high Δm in the V1500 Cyg stars is thought tobe due to high magnetic fields in the systems.



• The hibernation theory was proposed to explain theabnormally low observed space density of novae.

• As the nuclear burning on the white dwarf turns off , theincrease in orbital separation dominates the system.

• The accretion rate slows and eventually turns off .

• There are (at least) two observable consequences of the

change in the accretion rate.

Shara et al. (1986)








Shara et al. (1986)



As the accretion rate declines, the magnitude of thesystem must fade, eventually drastically.

Time

M a g n i t u d e



As the accretion rate declines, the system will passthrough other CV classifications.

Nova

Nova-Like

DwarfNova

Hiberna2ng

DwarfNova

Nova-Like

N e t A c c r e t i onR

a t e D e c r e a s e s

N e t A c c r e t i o n R a t e I n c r e a s e s



As the accretion rate declines, the magnitude of thesystem must fade, eventually drastically.

Time

M a g n i t u d e



We can construct long term light curves of oldnovae to search for secular fading trends.

Neeley et al. (in prep)

For seven sources,average decline of 1.4 mag/century.

Decline = 1 mag/century

1933 2010



Sometimes we also catch weird things, that don’tyet have a good theoretical explanation.

Schaefer (in prep)

14#

15#

16#

1870# 1890# 1910# 1930# 1950# 1970# 1990# 2010#

M a g n i t u d e

YEAR%

Q%CYG%(with%yearly%average%by%source%in%quiescence)%

Sonneberg#

AAVSO#Blue#

Shugarov#B#

Literature#Blue#

Asiago#

Harvard#

AAVSO#V#

Czech#

AFOEV#

Shugarov#V#

Steavenson#

Peek#

Barnard#

Literature#V#

Schmidt+#

Copeland#

Roboscope#

Eruption



I am looking at a much larger sample to determinethe average behavior of post-nova systems.

321 Systems



The Harvard College Observatory plate archive holdsmore than 500,000 plates dating to the 1890s.



The DASCH Project, led by Josh Grindlay, isworking to scan all of the plates at CfA.

DASCH




DASCH




DR2 (b down to 60°) Coming October 1! DASCH



One of the biggest challenges is actually locating thequiescent counterpart of the nova.

Downes & Shara Catalog



Tappert, Ederoclite, Schmidtobreick, and Vogt areworking to identify old nova counterparts.

Tappert et al. (2012)



We can monitor systems and watch as they transition fromone CV type to another, e.g. GK Per.

Shara et al. (2012)



We can monitor systems and watch as they transition fromone CV type to another, e.g. GK Per.

Payne-Gaposchkin (1957)

JD - 2400000

M a g n i t u d

e



V1017 Sgr has had many dwarf nova eruptions andone classical nova eruption since 1901.

1901 – Dwarf Nova

1919 – Classical Nova

1973 – Dwarf Nova

Webbink et al. (1987)



Z Cam was the first dwarf nova around which anancient classical nova shell was detected.

Shara et al. (2012)



Z Cam is quite possibly associated with a guest starrecorded by Chinese astronomers in 77 BC.

Shara et al. (2012); Johansson (2007)



AT Cancri is the second known dwarf nova with aconfirmed nova shell around it.

Shara et al. (2012)

1’

FUV NUV[NII]



The AT Cancri shell looks very similar to that of GK Per & T Pyx, with Rayleigh-Taylor knots.

Toraskar et al. (2013)



The spectrum of the AT Cancri shellconfirms that it is very bright in NII.

Shara et al. (2012)



BK Lyn recently transitioned from nova-like to adwarf nova, and was likely a nova in 101 A.D.

Patterson et al. (2013)



So it took BK Lyn 2000 years for DNe to begin, asopposed to ~50 years for GK Per—a Porb eff ect?

Patterson et al. (2013)



CK Vul remains the most controversial old nova /eruptive stellar merger event.

Hajduk et al. (2013)



Looking at a handful of systems gives mulitipleresults; a large-scale survey is crucial.

Time

M a g n i t u d e

Time

M a g n i t u d e

Time

M a g n i t u d e

e.g. V603 Aql

e.g. V1500 Cyg

e.g. Q Cyg




Post-nova systems:

• Fade

• Brighten

• Stay the Same

• Change States

• Quickly

• Slowly

• Are Exciting!

a new review of old novae

Documents