Dynamic Andromeda:Novae and Variable Stars in M31
Yi Cao2nd year graduate at Caltech
On Behalf of the Palomar Transient Factory collaboration
Yi Cao / Tsinghua Transient Workshop 2
Outline
• Novae• R Coronae
Borealis stars
(Credit: P. Nugent)
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 3
Summary of PTF M31 Surveys
Filter: R or gExp. Time: 60 secField of View: 7.2 deg2
Limiting mag: 20Cadence: 10min-1dEpochs: 1400
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 4
Phase Space of Cosmic Explosions
(Kasliwal, 2011, PhD Thesis)Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 5
Nova Explosion Mechanism
Periodic explosions in some white dwarf binary systems
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 6
Nova light curves: diversity
(Cao et al. 2012)
Vega mag:Red: R (PTF)Blue: BGreen: g
AB mag:Purple: NUV
Time (days)
mag
nitu
de
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 7(Cao et al. 2012)
Vega mag:Red: R (PTF)Blue: BGreen: g
AB mag:Purple: NUV
Time (days)
mag
nitu
de
Nova light curves: diversity
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 8
Nova light curves: diversity
(Cao et al. 2012)
Vega mag:Red: R (PTF)Blue: BGreen: g
AB mag:Purple: NUV
Time (days)
mag
nitu
de
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 9
Nova light curves: “MMRD” Relation
(Cao et al. 2012)(Kasliwal et al. 2011)
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 10
R Coronae Borealis stars
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 11
R Cor Bor Stars outside the Milky Way and Magellanic Clouds
Nov 6, 2012
(Tang, Cao et al. in prep.)
Yi Cao / Tsinghua Transient Workshop 12
Summary
• Novae show diverse photometry evolution, which implies rich explosion mechanisms.
• There is a subclass of novae that do not obey empirical “MMRD” relation.
• Systematical search for M31 RCB stars will help determine their rate and improve our understanding of white dwarf binaries.
Nov 6, 2012
Beyond Palomar Transient Factory
Yi CaoOn Behalf of collaboration of iPTF
and ZTF
14
PTF Cadence:5 day to 3 day to 2 day
Oct 31, 2012
• July 2009: Commissioned• Rest of 2009: Station Fire
• Year 2010Cadence of 5 day + 1 day(twice a night)Early 2011: 1000+ SN mark
• Year 2011: Cadence of 3 day + 1 day(twice a night)
• Year 2012: Cadence of 2 day only(twice a night)
1 day5 day to 3 day
Yi Cao / Tsinghua Transient Workshop 15Nov 6, 2012
Palomar Transient Factory
Yi Cao / Tsinghua Transient Workshop 16
Fast cadence
• Orphan GRB• Shock breakout of core-collapse supernovae• Infant Type Ia supernova• The unanticipated
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 17
“Orphan” Afterglow of GRB?
Cenko et al. 2012, submitted
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 18
Robo-AO (PI: Barenec)(S. Tendulkar’s Thesis Project)
Electronics Rack
Cassegrain Instrument
Laser Projector
1.5-m telescope
Robo-AO
• Fully-automated AO system
• UV laser beacon
• Visible + NIR observations
• Rapid response: < 60 s overhead
Performance
• 44” FoV
• 0.11” FWHM in r’ band
• 16 mag tip-tilt star
• ~20% z’ band Strehl
Caltech, USA & IUCAA, India
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 19
Robo-AO
2 “
One Robo-AO night!
• Transient response
– TDF vs central SN
– Progenitor location
– Resolved photometry
• Large Surveys (Area + Time)
– Stellar + asteroid multiplicity
– Kepler Planet CandidatesNov 6, 2012
Yi Cao / Tsinghua Transient Workshop 20
SED Machine (PI: Konidaris)(Grad. student: S. Ben Ami)
Nov 6, 2012
21
SED Machine Robotic Spectroscopy
Yi Cao / Tsinghua Transient Workshop 22
Software: Automatic Classifier
Nov 6, 2012
Yi Cao / Tsinghua Transient Workshop 23
iPTF
• P48 survey telescope + P60 SED machine + P60 Robo-AO + P200 follow-up
• Start from 2013• Big focus on supernovae:
– Early discovery of SN Ia (Yi Cao’s thesis project)– Shock breakout of Core-collapse SNe
Nov 6, 2012
24
The new Zwicky Transient Facility (ZTF) will find rare fast transients beginning in 2015.
PTF ZTF
Active Area 7.26 deg2 35 deg2
Readout time 36 sec 10 sec
Relative Survey Rate 1x 6x
Filters Mould R, g’
r’, g’
New ZTF camera: 12 6k x 6k e2v CCDs
Existing PTF camera MOSAIC 12k
The Zwicky Transient Facility
P48Discovery: 35 sq deg!
PI: S. Kulkarni
P60:Follow-Up
The SED MachinePI: N. Konidaris
P200:Spectroscopy