Download ex-lup-v3

Dev Ashish Khaitan
UR IR Lab, B&L 427
Hayashi track for pre main
sequence objects
•The Hayashi track is a path taken
by protostars in the HertzsprungRussell diagram after the
protostellar cloud has reached
approximate hydrostatic
equilibrium
•T Tauri stars are pre-main
sequence stars – the youngest
visible F, G, K, M spectral type
stars (<2 Solar mass).
•Between 1-3 Myr is where our
interests lies.
Caroll and Ostlie. An Introduction to Modern Astrophysics. 2007 Pearson-Addison Wesly
(I should say BoB)
Model of T – Tauri stars
•The Accretion
disk consists of
micron sized dust
particles that
detectable in
infrared
wavelengths
•That what we
are going to look
at.
Caroll and Ostlie. An Introduction to Modern Astrophysics. 2007 Pearson-Addison Wesly
(I should say BoB)
Ex Lup (i)
•Model being used to describe the star
•0.2 AU ring of emptiness around the star from the best models
created using RADMC & RAYTRACE (Sipos et al. 2009)
•Undergone a big outburst in 2008.
Sipos et al. 2009. EX Lupi in quiescence. Astronomy & Astrophysics manuscrip no. exlup-quiescence. arXiv:0906.3168v1
1955-56 Outburst
• Variability of 5 magnitudes
•There hasn’t been such a large outburst again till 2008.
pg.671. Steven Stahler & Francesco Palla. The Formation of Stars. 2004 WILEY-VCH Verlag GmnH & Co. KGaA,
Weinheim
AAVSO Data
1993-94 Outburst
•Recorded over a period of
~600 days
•Several “mini-outbursts”
changing the magnitude by
an order of 1.5.
G.H. Herbig, C. Aspin, Alan C. Gilmore, Catherine L. Imhoff and Albert F. Jones. The 1993-1994 Activity of EX Lupi, The Publications of the Astronomical
Society of the Pacific, Volume 113, Issue 790, pp. 1547-1553
Variability in the 90s
•10 years of data shows
that variability in the visual
magnitude are common
•“Artifical floor” in the data
•A magnitude change of ~2
is approx change in
luminosity of ~2.5
•Believe it to be an
accretion related event.
AAVSO data
Accretion Rate
Excess emission over photosphere ~ Lacc = G M (dM/dt) / R
•For a star like this we
should expect accretion
rate to be around
~10-9M ⊙ /yr
•The increased luminosity
should increase the rate by
one “bar”
•The calculated value from
Hα and Paβ gives us 4 x
10-10M☉/yr (i).
Nauria Calvet Presentation on Issues in modelling SEDs of Low Mass YSO. Spitzer Conference 2008.
Compiled at UR IR Lab, B&L 427.
(i) Sipos et al. 2009. EX Lupi in quiescence. Astronomy & Astrophysics manuscrip no. exlup-quiescence. arXiv:0906.3168v1
Abraham et al. 2009 –
crystallinity + light curve
•Light Curve for the 2009 outbreak, 5 magnitude shift
• Graph b) shows 9.7µm amorphous silicate feature
•The paper states there are forsterite features at 10 &
11.2µm. From their plots this is not evident. At best all
that can be seen is a shoulder at those wavelengths.
a)
b)
c)
d)
Spectrum of Interstellar grains
measured towards the Galactic Center
EX Lup in Quiescence taken on March
18th 2005
EX Lup in mid-ourburst taken on April
21st 2008
Red line, ground-based spectrum of
Comet 1P/Halley, dash–dot line,
Spitzer spectrum of the ejecta from
Comet 9P/Tempel 1 during the Deep
Impact experiment
Ábrahám, P.; Juhász, A.; Dullemond, C. P.; Kóspál, Á.; van Boekel, R.; Bouwman, J.; Henning, Th.;
Moór, A.; Mosoni, L.; Sicilia-Aguilar, A.; Sipos, N. Episodic formation of cometary material in the outburst of
a young Sun-like star, Nature, Volume 459, Issue 7244, pp. 224-226 (2009).
2000-2010 Light Curve
Pre Outburst
Mid
outburst
Post
outburst
AAVSO data
ν Fν vs. Wavelength
•SED Parameters:
•3840 K (i)
•1.95R⊙ (ii)
•Normalized at h band
•Before and after
outburst Spectra from
Spitzer
•IRAS data agrees with
the quiescent phase
because of the 5µm
band pass.
Above graph created at the UR IR Lab, B&L 427
(i)
Taken from Scott J. Kenyon & Lee Hartman, Pre-Main Sequence Evolution in the Taurus-Auriga Molecular Cloud,
Astrophysical Journal Supplement Series, 101:117-171, 1995, November
(ii)
Calculated by normalizing the SED at H band data from 2MASS, JP11 & DSS
4 epochs of data
•The 10µm flux is
higher by a factor of 5
before and after the
outburst
Mid OB
Photosphere
•There is a shoulder at
around 11µm visible
after the outburst.
•Pre OB T = 3840K
•Mid OB T = 6800K
Pre OB
Photosphere
Graph produced at UR IR Lab, B&L 427
The spectrum data has been collected by the Spitzer Space Telescope, retrieved using Leopard, and reduced using
ECO by Patrick Sheehan
Spectrum AORs (5645056, 11570688, 27039232, 28476672)
SED Index
•It is an indication of the
flatness of the disk
•A flat black disk will have an
SED index of -4/3
•Calculating indices for gas to
dust ratio (depletion) in the
upper layers
•More negative values are
called bluer. They signify a
lower ratio.
•Redder (+ve indices) are
where a substantial amount of
dust can still be found in the
upper layers.
•Approx. ~.2 except for Apr.
2008 where it is extremely
blue.
Graph Produced at UR IR Lab, B&L 427.
Reference for index and interpretation:
Dan M. Watson et al. 2009, Crystalline Silicates and Dust Processing in the Proto Planetary Disks of the Taurus
Young Cluster, Astrophysical Journal Supplement Series, 180:84-101, 2009 January
Quick Comparison of Index
•Calculated values:
•L: 2.89x 1033 ergs/s
= .75L☉
•Mbol : 5.1
•mbol : 11.0
•From the graphs it looks
like it is approx. 2 Myr &
0.5M ⊙
Ex Lup – Pre OB
•Seems like a typical TTauri star in quiescence.
EX Lup Data point Produced at UR IR Lab, B&L 427.
Graph from:
Dan M. Watson et al. 2009, Crystalline Silicates and Dust Processing in the Proto Planetary Disks of the Taurus
Young Cluster, Astrophysical Journal Supplement Series, 180:84-101, 2009 January
Stellar Parameters
Parameter
Value
Distance (I)
155 pc
Stellar Temperature (ii)
3840 K
Radius (iii)
1.95R⊙
mbol
11.0
Mbol
5.1
Luminosity
.75L☉
Mass
.6M☉
Parameter
Distance
Inclination
Temperature (Star)
Mass (Star)
Radius (Star)
Visual Extinction
Inner radius of Dusty disk
Outer radius of Dusty disk
Scale height
Flaring index
Exponent of radial density
profile
Total Mass of disk
Luminosity
Fitted Value
155 pc
20°
3840 K
.6 M⊙
1.6R⊙
0
0.2 AU
150 AU
0.12
0.09
-1.0
0.025 M⊙
0.7 L⊙
Table on right from: Sipos et al. 2009. EX Lupi in quiescence. Astronomy & Astrophysics manuscrip no. exlup-quiescence.
arXiv:0906.3168v1
Table on the right created at UR IR Lab, B & L 427,
(i) Ábrahám, P.; Juhász, A.; Dullemond, C. P.; Kóspál, Á.; van Boekel, R.; Bouwman, J.; Henning, Th.; Moór, A.; Mosoni, L.;
Sicilia-Aguilar, A.; Sipos, N. Episodic formation of cometary material in the outburst of a young Sun-like star, Nature, Volume
459, Issue 7244, pp. 224-226 (2009).
(ii) Taken from Scott J. Kenyon & Lee Hartman, Pre-Main Sequence Evolution in the Taurus-Auriga Molecular Cloud,
Astrophysical Journal Supplement Series, 101:117-171, 1995, November
(iii) Calculated at the UR IR Lab, B&L 427 by fitting the blackbody to the h band
Stellar Parameters through
outburst
Parameter
Value
Parameter
Value
Distance
155 pc (i)
Distance
155 pc(i)
Stellar Temperature
3840 K(ii)
Stellar Temperature
6800 K (i)
Radius
1.95R⊙
Radius
1.95R⊙
Luminosity
.75L☉
Luminosity
7.5L☉(i)
Mass
.6M☉
Mass
.6M☉
Accretion Rate
4 x 10-10M☉/yr(iiI)
Accretion Rate
5x 10-7M☉/yr
Pre Outburst Accretion Rate probably too low.
(Lee Hartmann Private Communication)
Tables right created at UR IR Lab, B & L 427,
(i) Ábrahám, P.; Juhász, A.; Dullemond, C. P.; Kóspál, Á.; van Boekel, R.; Bouwman, J.; Henning, Th.; Moór, A.; Mosoni, L.;
Sicilia-Aguilar, A.; Sipos, N. Episodic formation of cometary material in the outburst of a young Sun-like star, Nature, Volume
459, Issue 7244, pp. 224-226 (2009).
(ii) Taken from Scott J. Kenyon & Lee Hartman, Pre-Main Sequence Evolution in the Taurus-Auriga Molecular Cloud,
Astrophysical Journal Supplement Series, 101:117-171, 1995, November
(iii) Sipos et al. 2009. EX Lupi in quiescence. Astronomy & Astrophysics manuscrip no. exlup-quiescence. arXiv:0906.3168v1
Accretion Rate
Excess emission over photosphere ~ Lacc = G M (dM/dt) / R
Mid
Outburst
Pre
Outburst
Nauria Calvet Presentation on Issues in modelling SEDs of Low Mass YSO. Spitzer Conference 2008.
Compiled at UR IR Lab, B&L 427.
Where does the Flux come from?
Nauria Calvet Presentation on Issues in modelling SEDs of Low Mass YSO. Spitzer Conference 2008.
Dust grain OpacitiesShorter Wavelengths
Dust grain OpacitiesLonger Wavelengths
Two temperature (warm & cold)
model
•k(cm2/gm) are small grain opacities, a’s are the mass/d2 of that component.
•Solid angles represent optically thick disk + carbon + very large silicates.
•Model tested against full self-consistent radiative transfer model on IS Tau(Sargent
et al. 2006).
•The model is designed to run from 7.7 -37 microns.
•We are running the model from 5.5-15 microns.
William Forrest Presentation on High Temperature Silicates in Protoplanetary Disks.
Pre-Outburst
[AOR:5645056]
•Strong 10µm
amorphous silicate
feature
•Shoulder visible at
around 11-11.5µm
•Reduced chi squared
of 1.42.
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest
Pre Outburst Residuals
[AOR:5645056]
•Silicates &
blackbodies have
been subtracted from
the flux
•Warm Forsterite
feature
•Very small mass by
fraction
•Our model does not
capture the apparent
features at ~8.2 &
9.5µm.
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Pre-Outburst
[AOR:11570688]
•Strong 10µm
amorphous silicate
feature
•Shoulder visible at
around 11-11.5µm
•Reduced chi squared
of 1.22
•General analysis
agrees with Abraham
et al.2009.
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest
Pre Outburst Residuals
[AOR:11570688]
•Silicates &
blackbodies have
been subtracted from
the flux
•Only warm Forsterite
feature
•Very small mass by
fraction
•Our model does not
capture the apparent
features at ~8.2 &
9.5µm.
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Dust Composition
Sipos et al. 2009 and our data
80
70
60
•SmAmO & LgAmP mass
fractions agree
•Sipos et al. have found
trace quantities of Enstatite
and less Forsterite.
Sipos et al. 2009
Mass Fraction %
50
40
Mass Fraction %
Pre-Outburst 3/2005
30
20
10
•Remarkable agreement.
0
SmAmP SmAmO
LgAmP
LgAmO
Enst
Forst
Slica
Sipos et al. 2009. EX Lupi in quiescence. Astronomy & Astrophysics manuscrip no. exlup-quiescence. arXiv:0906.3168v1
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Mid Outburst
[AOR: 27039232]
•Strong 10µm
amorphous silicate
feature but most of
the spectrum has
changed
•Plateau visible at
around 9.5-11.5µm,
the composition has
changed
•Flux of star a lot
higher at these
wavelength
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest
•Reduced chi squared
of 0.592.
Mid Outburst Residuals
[AOR:27039232]
•Silicates &
blackbodies have
been subtracted from
the flux
•The model fits the
data pretty nicely
•There are visible
lines of forsterite,
enstatite and silica.
•No strong feature at
~8.2 & 9.5µm.
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Post Outburst
[AOR: 28476672]
•Strong 10µm
amorphous silicate
feature
•Temperature back to
pre OB levels
•Shoulder visible at
around 11-11.5µm
•Presence of warm
forsterite, a little
enstatite and cool
silica.
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest
•Reduced chi squared
of 1.31
Post Outburst
[AOR: 28476672]
•Modeling the data
from 15-37
•We happen to have
the cool temperature
from the previous
model as the warm
temperature for this
model.
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest
Post Outburst Residuals
[AOR:28676672]
•Silicates & blackbodies
have been subtracted
from the flux
•The fit of the model to
the data is not very
good. Probably the
worst of the set
•There are visible lines
of forsterite & enstatite.
•Apparent un-modeled
feature at ~8.2µm
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Post Outburst Residuals
[AOR:28676672]
•Silicates & blackbodies
have been subtracted
from the flux
•The fit of the model to
the data is not very
good. Probably the
worst of the set
•There are visible lines
of forsterite & enstatite.
•Apparent un-modeled
feature at ~8.2µm
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Composition Mid & Post Outburst
•Presence of
crystalline silicates
•A lot more large
amorphous silicates
present after the
outburst
Dust Composition
60
Mass Fraction %
Mid-Outburst04/2008
50
40
30
•Abraham et al.
2009 states
presence of just
Forst. but we have
substantial
quantities of Enst.
and silica.
Mass Fraction %
Post-Outburst 10/2008 (5.515)
20
10
0
SmAmP
SmAmO
LgAmP
LgAmO
Enst
Forst
Slica
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Composition of Inner Disk vs.
Outer Disk.
60
50
Mass Fraction % PostOutburst -10/2008 (5.515)
40
30
Mass Fraction % PostOutburst -10/2008 (1537)
20
10
0
SmAmP
SmAmO
LgAmP
LgAmO
Enst
Forst
Slica
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Disk Composition Through
outburst
Dust Compositon
80
70
Mass Fraction % PreOutburst - 8/2004
60
Mass Fraction % PreOutburst -3/2005
50
40
Mass Fraction % MidOutburst- 04/2008
30
20
Mass Fraction % PostOutburst -10/2008 (5.5-15)
10
0
SmAmP
SmAmO
LgAmP
LgAmO
Enst
Forst
Slica
Data collected using Spitzer Space Telescope, retrieved using Leopard, reduced using ECO by Patrick Sheehan
Analysis done by using the Two Temperature Model created by B. Sargent,, C. Tayrien,, W. Forrest and graphed at
UR IR Lab, B&L 427
Where does the Flux come from?
F    B    T
A
 
d
2
Where
.

 
k i mi
i
A
F  
B    T
OR
 
R
d
2
2
:.

 1 e


2


F   d star


R star  F   B   
 B  pi   1  e   
 

1
2


i
Fn  mi
k i mi
d
2
Fn  mi
• Did a continuum
Subtraction using our 2
blackbodies for the 10
micron feature (Furlan et al.
2006)
•This is not a direct measure
of the mass but gives us a
rough idea if the population
has grown or gotten smaller.
AORID
∫Fν
5645056
1.059 x 10-10
11570688
0.988 x 10-10
27039232
6.107 x 10-10
28476672
1.42 x 10-10
Where does the Flux come from?
 F   d star2 


R star  F   B   
 B  pi  1  e   
 

1
2
F   F smAmP  F smAmO  F lgAmP  F lgAmO  F enst  F forst  F slica
B     T 
2 h
c
2
3

1

e
h 
k T

 1
  0.1
dstar  155 pc
Where does the Flux come from?
AORID
Warm Temp (K)
Cool Temp (K)
Warm Radius (AU)
Cool Radius (AU)
5645056
700
247
0.485
--
11570688
700
247
0.476
--
27039232
1400
323
0.333
2.251
28676672
700
247
0.485
--
• There are no cool features for the 10 micron feature, the
black body only contributes to the “reddening”.
•The sublimation point has been pushed out in our model.
•We are looking at approx. the same dust population in all the
spectra
What’s going on?
•PRE-Outburst: The star is a 3840K M0 star with an accretion disk with
visible silicate features and very little crystal and an accretion disk <0.2AU
•MID-Outburst: The star temperature rises to 6800K and the accretion disk
is pushed out >0.2AU. The upper layers of the disk are depleted as are
visible from the SED index and we see crystalline silicates. This is either
because the upper layer sublimates and are we looking further into the disk
where crystals reside or the high temperature crystallize amorphous
silicates to crystalline silicates.
•POST-Outburst: The disk temperature is back to PRE-OB levels but we do
not know how fast the star cools down. We see a lot of large amorphous
grains and clumping is a possibility to explain this. We see the n6-13 index is
back to PRE-OB levels.
Acknowledgements:
Prof. William Forrest
Cyprian Tayrien
Manoj Puravankara
Patrick Sheehan &
Emily May
Thank you
***
“Poets say science takes away from the beauty of the stars - mere globs of gas atoms. I, too,
can see the stars on a desert night, and feel them. But do I see less or more?”.
-Richard Feynman