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Subaru Users Meeting (January 15, 2009)
Light-Echo Spectrum revealed types of
Tycho Brahes’s 1572 & Cas A SNe
Tomonori Usuda (SUBARU)
Oliver Krause, Stephan M. Birkmann, Miwa Goto (MPIA),
Takashi Hattori (Subaru Telescope),
Masaomi Tanaka, Ken’ichi Nomoto (Univ. of Tokyo),
George H. Rieke, Karl A. Misselt (Steward Observatory)
Cas A
Blue：X-ray (CXO)
Green：Optical (HST)
Red：Mid-IR (SST)
Tycho
BGY：X-ray (CXO)
Red：Mid-IR (SST)
White: Near-IR
Subaru Users Meeting (January 15, 2009)
Outline
1. Review Galactic Supernova Remnants (SNRs) &
Historical Supernovae (SNe)
•
Cassiopeia A (Cas A)
•
Tycho Brahe’s SN 1572
2. Special Observation Tool: Light echo
3. Case 1: Cas A – Observation / Results
4. Case 2: Tycho – Observation / Results
5. Future plans & Conclusion
Subaru Users Meeting (January 15, 2009)
Review Galactic Supernova?
RCW86
G11.2
Kepler
Designation
RCW86
G11.2-0.3
Lupus
Crab
3C58
Tycho
Kepler
Cas A
Year
185
393
1006
1054
1181 ?
1572
1604
1680 ?
Type
II / Ia ?
?
Ia
II
II ?
Ia
Ia / Ib ?
Ib / Ic / II ?
G1.9+0.3
1870?
?
Tycho Brahe
Crab
Cassiopeia A
G1.9
Subaru Users Meeting (January 15, 2009)
Cassiopeia A
• Second youngest SNR known in our Galaxy
(cf. G1.9+0.3 discovered by CXO in 05/13/2008)
• Well known & studied SNR
• It might be appeared around 1680, however no
historic records
(e.g., SN1054: Crab by Teika Fujiwara『Meigetsuki』)
Q1: What kind of supernova explosion?
Q2: Why it was not witnessed in 17th century?
Subaru Users Meeting (January 15, 2009)
Tycho Brahes’s 1572 Supernova
• Well known & studied SNR
• Danish astronomer Tycho Brahe found very bright `new
star’ in the constellation of Cassiopeia on the evening of
11th of November in 1572. He had observed its brightness,
color, and proper motion until March in 1574.
• In 20th century, the `new star’ = A supernova
–
–
–
–
Brightness & Color light curve ←→ Theoretical Model of SN
X-ray observations → Spherical symmetry of metal abundance
Radio etc. → No pulser
Optical → Candidate of surviving binary companion of SN 1572
Q: Is SN 1572 really type Ia Supernova?
→ Classified by only optical spectrum
``Astronomie Populaire” by Camille Flammarion (Paris, 1884)
Subaru Users Meeting (January 15, 2009)
How we can solve the
mysteries on the past?!
Light Echo can go back to
the past rewind time
Subaru Users Meeting (January 15, 2009)
Light echoes – Rewinding time
to historic SN explosions
Echo (sound)
Subaru Users Meeting (January 15, 2009)
Light echoes – Rewinding time
to historic SN explosions
Blue : Light of SN explosion arrived at Earth in 1572.
Red : Scattered-light echo by dust arrives now.
Subaru Users Meeting (January 15, 2009)
Light echoes – Rewinding time
to historic SN explosions
"As Professor J.H. Oort has pointed out to us, the illumination of
surrounding clouds might become a spectacular phenomenon in
the case of galactic supernovae. The search for the illumination of
galactic clouds by past suspected supernovae such as Tycho's star
and the stars which gave rise to the Crab Nebula and perhaps
other nebulosities presents an interesting problem”.
SN 1987A
By Zwicky Rev. Mod. Phys. 12, 66 (1940)
Suntzeff
Subaru Users Meeting (January 15, 2009)
Light echoes – Rewinding time
to historic SN explosions
However… Observation of Light echo is very difficult.
• Very Faint (Light echo became fainter and fainter day by day)
→ Even though can detect light echo, difficult to take its spectrum
• When? Where? How bright?
→ Just wait and Searching
Dust cloud
SN 1987A
SN
Echo geometry
Suntzeff
Subaru Users Meeting (January 15, 2009)
Observations
• When? Where? How bright?
→ Monitoring and ToO (Target of Opportunity)
→ International collaborations with MPIA
• Calar Alto 2.2m & 3.5m + Wide Optical Camera
PI: Oliver Krause (MPIA)
→ Monitoring & Looking for optical light echo
• Subaru Telescope 8.3m + FOCAS
PI: Tomonori Usuda (Subaru/NAOJ)
→ Imaging: Re-confirmation of light echo
Spectroscopy: Take its optical spectrum
Subaru Users Meeting (January 15, 2009)
Case 1: Cassiopeia A
Subaru Users Meeting (January 15, 2009)
Associated scattered light echo by
Calar Alto 2.2m & SUBARU 8.2m
October 9, 2007
Spectroscopy
Detect optical light echo!
R = 23.4 mag / arcsec2
SUBARU
+
FOCAS
Subaru Users Meeting (January 15, 2009)
Results: Spectroscopy
He I
He I
Went back in time
toHαdetect
light that
originally arrived at Earth more
than 330 years ago.
• dl=2.4nm (ll=476~989 nm) / Av=3.1 mag
• Spectral features of Supernovae
• Exp time=5.5 hours
• Broad line width (17,000 km/s) / P-Cygni profile
• Strong H & He emission lines
Subaru Users Meeting (January 15, 2009)
Type
I
sub-type
Results
Spectral Feature
Ia
• No Hydrogen lines
• Strong Si lines
• Remarkable Fe lines in later phases
Ib
• No Hydrogen lines
• Remarkable He lines in max period
• Weak Si lines / No Fe lines
Ic
• No H & He lines
• Weak Si lines / No Fe lines
II
• Strong H lines
• Light curve → II-P-type (plateau),
II-L-type (linear), II-n-type (narrow)
IIb
• Visible H lines
• Remarkable He lines
II
Subaru Users Meeting (January 15, 2009)
Comparison with the proto-typical
type IIb SN 1993J
Subaru Users Meeting (January 15, 2009)
Type
I
sub-type
Results
Spectral Feature
Ia
• No Hydrogen lines
• Strong Si lines
• Remarkable Fe lines in later phases
Ib
• No Hydrogen lines
• Remarkable He lines in max period
• Weak Si lines / No Fe lines
Ic
• No H & He lines
• Weak Si lines / No Fe lines
II
• Strong H lines
• Light curve → II-P-type (plateau),
II-L-type (linear), II-n-type (narrow)
IIb
• Visible H lines
• Remarkable He lines
II
Subaru Users Meeting (January 15, 2009)
Comparison with the proto-typical
type IIb SN 1993J
Cas A was a type IIb SN & Red Supergiant
(13-20 Solar Mass) as progenitor star
Subaru Users Meeting (January 15, 2009)
Case 2: Tycho
Subaru Users Meeting (January 15, 2009)
Results: Imaging
N
E
Slit position
30”
Back box: Previous light echo position in 2006 a: Calar Alto 2.2m
b: Subaru＋FOCAS
Red+ mark: Brightest position (R=23.5 mag)
→ Slit position (2.8”x2.0”) for spectroscopy by FOCAS
→ Subtraction of sky & nebulosity lines
Subaru Users Meeting (January 15, 2009)
Results: Spectroscopy
He
Hα
Si
Optical spectrum of the light that
originally arrived at Earth in 1572
• dl=2.4nm (ll=380~920 nm) / Av=2.4 mag
• Exp time=2.5 hours (Red) + 1.5 hours (Blue)
• Remarkable spectral features of Supernovae
• Broad line width (9,000~12,000 km/s)
• No H & He lines
• Strong absorption lines of Si and Fe
Subaru Users Meeting (January 15, 2009)
Type
I
sub-type
Results
Spectral Feature
Ia
• No Hydrogen lines
• Strong Si lines
• Remarkable Fe lines in later phases
Ib
• No Hydrogen lines
• Remarkable He lines in max period
• Weak Si lines / No Fe lines
Ic
• No H & He lines
• Weak Si lines / No Fe lines
II
• Strong H lines
• Light curve → II-P-type (plateau),
II-L-type (linear), II-n-type (narrow)
IIb
• Visible H lines
• Remarkable He lines
II
Subaru Users Meeting (January 15, 2009)
Results: Spectroscopy
He
Hα
Si
• Spectral features of Supernovae
• Broad line width (9,000~12,000 km/s)
• No H & He lines
• Strong absorption lines of Si and Fe
→ Type Ia Supernova
Subaru Users Meeting (January 15, 2009)
Type
I
sub-type
Results
Spectral Feature
Ia
• No Hydrogen lines
• Strong Si lines
• Remarkable Fe lines in later phases
Ib
• No Hydrogen lines
• Remarkable He lines in max period
• Weak Si lines / No Fe lines
Ic
• No H & He lines
• Weak Si lines / No Fe lines
II
• Strong H lines
• Light curve → II-P-type (plateau),
II-L-type (linear), II-n-type (narrow)
IIb
• Visible H lines
• Remarkable He lines
II
Subaru Users Meeting (January 15, 2009)
Various type Ia Supernova
Type Ia SN = Cosmological distance indicator
→ Discovery of the accelerated expansion of Universe
Luminosity is NOT uniform!
Subluminous
Si
Ca
Fe
Si
Ni
Normal
Type Ia SN
Si
Ca
Fe
Ni
Overluminous
Si
Ca
Fe
Ni
Reason why its variety of luminosity?
→ Accurate cosmological distance indicator?
Subaru Users Meeting (January 15, 2009)
Results: Spectroscopy
Overluminous type Ia
Normal type Ia
Subluminous type Ia
Subaru Users Meeting (January 15, 2009)
Unique opportunity to test theories of
SN Explosion mechanism
10 arcmin
Point source
SNe in extra-galaxies
Tycho’s SNR
d=100 Mpc
d = 3.8 kpc
Subaru Users Meeting (January 15, 2009)
Spatial Resolved Investigation
HighVelocity Ca II
Subaru Users Meeting (January 15, 2009)
Conclusions
• For the first time, spectra of historical Galactic supernovae
(Cas A & Tycho) have been secured.
• Cas A: Type IIb SN & Red Supergiant (13~20 Mo)
• Why Cas A was not witnessed in 17th century
Type IIb SN fade away quickly, poor weather of several
days, higher extinction (Av~8), peak brightness (~3 mag)
• Tycho: Normal type Ia SN & d=3.4kpc (cf. 2.3~2.8 kpc)
• Light echoes at different position angles from the source
→3D aspect
→ Spatial structure of SN outburst mechanism
Subaru Users Meeting (January 15, 2009)
Mahalo !