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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