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PICTURE, a sounding rocket to characterize the debris disk of Epsilon Eridani Ewan. S. Douglas1 ([email protected]), Chris Mendillo2, Brian Hicks2, Jason Martel2, Timothy A. Cook2, Ron Polidan3, Supriya Chakrabarti2. 1 Department of Astronomy, Boston University, Boston, MA. 2Center for Atmospheric Research, Department of Physics, University of Massachusetts Lowell, Lowell, MA. 3Northrop Grumman Corp. ABSTRACT Epsilon Eridani Debris Disk:Reidemeister et al.: ε Eridani et 10 IRAS MIPS MIPS (SED) SHARC II SCUBA 1.5 1 PICTURE FOV 0.5 -1 0 10 100 wavelength [µm] 1000 10 1533 Science and Wavefront 1024x1024 pixel, back-illuminated CCDs from Astro-E2 X-ray mission Sensing CCDs Inner &! Outer Working Angles! 1.5λ/d (0.5”) & 5” Pointing System Tip-Tilt steering mirror, 5 mas pointing (Mendillo et al. 2012a) 0 10 grain size [µm] • Baseline leakage: 1% amplitude (E ) mismatch (limiting central null to 2.5*10 • Measured Flight Deformable Mirror (DM) Surface Figure • Secondary/Spider Obscuration & Lyot Mask shape • Template source spectra (e.g. Pickles et al. 1998, via pysynphot) & surface brightness distribution • Shot Noise and Dark Current 0 planet 'A' -1 Purpose! Rigel 60 Sec Demonstrate nulling, record reference PSF ϵEri, Roll 1 >105 Sec Characterize Exozodi ϵEri, Roll 2 >105 Sec Characterize Exozodi The first PICTURE launch in and track speckles (Courtesy Figure October 13: Left: 2011. PICTURE launch. WSMR.) Right: Telemet (TM 2) failed 1 10 ediate (10-55A The most important result returned from the PIC In flight, the ACS acquired the calibration star, Rigel drive the star into the acquisition mirror pinhole. The the live angle tracker GSE display. An additional ACS the FSM at which point the FPS immediately locked o 200 Hz with a 5 Hz bandwidth. Analysis of the raw ce that the FPS stabilized the 627 mas RMS ACS radia also provides a high-precision measurement of the roc both the ACS body-pointing and the FPS stability A dustless simulation showing four regionsofof The predicted 3AU ring can seen above, scattered light (corners) from the DM at large The operation of the telescope in flight is confirm the circle is cut-off by the (horizontally radii and a residual central leakage from color the telescope PSF wastransmission much larger than anticipated, oriented) nuller minima at mismatch between Epilson Eridani (210 unknown. Unfortunately, the lightweight primary mi 0” and 0.9”. second observation) and Rigel (20 second).The remaining hardware was recovered intact and app not yet been conducted. U) Contrast The 5σ contrast curves at right are derived from the annular, one pixel wide, standard deviation of the expected background (from dustless simulation shown above) versus the star brightness (as in Bailey et al 2013). The star brightness is taken to be the peak pixel intensity of a smoothed, simulated bright output. Subtraction of a noisy reference PSF removes speckles and increases the effective contrast (solid red line) and enables imaging the expected inner debris disk. The Payload all the disk components is 1.1 × 10−4 . Model setup New Primary Mirror 1. Method seconds after launch, the main science data telemetry the TM transmitter power during flight. This TM ch shown in Figure 4, which carries all of the WFS and data, the in-flight performance of the nuller and activ of flight data has been recovered, unfortunately this acquired steering lock and thus the nuller had not be future analysis for determining some basic functionali -5) Backman et al. 2009 ice mixtures, Fig. 2. The βadapted ratio from of two silicate – water compared to a pure silicate composition, as a function of size for ε Eri. The bars show the size bins used in the inner Figure 8. (a) Perpendicular depth τsimulations five model components. two unresolvedline inner shows belts (dashed lines), outer “icy” ring (dotted (Sect. 4). disk The dashedThehorizontal ⊥ vs. position for the Reidemeister et al. 2011opticaldisk line), and ring+halo “silicate” dust populations (dot-dashed line) are shown. (b) Mass surface density vs. radius corresponding to the optical depth profiles in panel the dynamical blowout = 0.5. From the SED, Backman etof al.β (2009) Epsilon Eridani’s Spectral energy distribution (a), assuming grain compositions and material densities described in the limit text. The difference in slopes between the optical depth and mass surface density profiles is due to radial variation in model particle properties. infer a system of rings, shown above, (SED) shows excess at 24um out a significant flux AU) ring within 10AU, r ring (55-a90warm with a thin ring near 3AU, scattering and beyond, eindicating Dustthe grain properties The top panel of Figure 82.3. displays model profile Figure 9 is a two-dimensional representation of the ϵ Eri starlight with anradial expected integrated proposed by Reidemeister et al. (2011) to be of perpendicular optical depth τ⊥ , that is, fractional (unitless) debris disk system with a linear spatial scale, showing the -4 F knee in area the IRS at ∼ 20 µm in Fig. brightness of 2*10 surface density (m2 of grainThe cross-sectional per m2spectrum of *. disk sub-mm ring, (inset halo, and inner 1) warm belts. The position of sustained byview solarofwind-driven Poyntingg. 1. A schematic the ε Eridani system’s archiof a panel, classical feature.warm Since exsurface area; e.g., Backman is 2004), and inphot/sec the bottom the silicate the innermost belt the is compared in the inset figure with (Freminiscent for PICTURE). * ~3e8 Robertson drag. Example wavefronts from the DM mirror arm of the nuller. cture. The outer ring is the region where the dust mass is procorresponding surfaceact density inferred from the optical one orbit solution for the candidate radial velocity planet composition of those silicates is not known, we have ced by parent planetesimals; the intermediate zone grain is the depth and model properties is displayed. The slopessilicate of the (Laor (Section 5.4). chosen astronomical & Draine 1993) (ρd = two functions across the sub-mm ring−3and halo are not equal e where it is transported inward by drag forces, possibly 3.5 g cm ). On the other hand, by analogy with5.the surDISCUSSION because the model includes smooth variation in the particle size eracting with a presumed outer planet; transport continface composition ofofKuiper the solar system the fiducial radii, so the ratio particle belt objects in 5.1. Some Implications of the Disk Model s through the inner region where dustdistribution interactsbetween with the (e.g., Barucci al. 2008), cross section (and thus optical depth) to massetsurface densitywe may expect many additional own inner planet. Two possible orbits varies of the innerwith planet slightly radius. The optical depths and ices mass densities The derived surface-densityitprofile species such as and organic solids. In particular, is for the small grain come shown. The outer part of the sketch (> 10two AU) is rings not to of the inner in Figure 8 are calculated by assuming ∆r to be ponent (Figureespecially 8) has a nearly natural to expect water ice present, givenconstant value from 35 to ale. Inset: The observed SED. The IRS spectrum (dots) values of 1 AU at 3 AU and 2 AU at 20 AU; they would scale 110 AU, consistent with very dynamics controlled by P–R radiation that the source of dust is a ”Kuiper belt” located far with drag or its corpuscular wind analog (Section 5.3). In contrast, ms from dust in the inner region andinversely exhibits a ∆r. charac- from the star (∼ 55–90 AU), and star itself has has a late Theµm. total The inferred mass in detected grains, that is, with sizes the the large-grain component surface density rising from 35 to istic “plateau” (“shoulder”) at λ ≈ 20–30 main class. Accordingly, tried mixfrom a few microns to a fewspectral hundred microns, carrying most of we also 90 AU. Thehomogeneous larger grains are less subject to drag forces, so their rt of the SED with a maximum at λthe≈radiating 70–80 surface µm, well area, is tures roughlyof 5 ×astrosilicate 10−3 M⊕ ∼ 0.4 with MLuna , 50% radial and distribution 70% volume fraction may reflect that of the underlying parent-body obed by several photometry points (symbols with 90% of which is inerror the large of (“icy”) grainice component of the sub- 1998) population. water (Li & Greenberg (ρd = 1.2 g cm−3 ). The rs), derives from the outer and intermediate mm ring. regions. The total bolometric fractional luminosity (Ldice-silicate /L∗ ) of The void is interior to thegsub-mm bulk density of these mixtures ρ = 2.35 cm−3 ring is inferred to be partly in ter m filled by two additional belts of particles with mean sizes and ρ = 1.89 g cm−3 , respectively. The optical constants of the mixtures were calculated by effective medium theory with the Bruggeman mixing rule. In all three cases (pure astrosilicate, two ice-silicate mixtures) the dust grains were assumed to be compact spheres. New Deformable Mirror new lightweight Carbide primary mirror is pressure Radiation ur modelAincludes gravitationalSilicon forces from the star and 2.4. new MEMS currently being manufactured by Northrop Grumman AOAconstants Xinetics.and adopting MieAtheory, inner planet, radiation and stellar wind pressure, drag Using the optical deformable ces induced by both stellar photons and stellar wind par- the radiation pressure efficiency Q , averaged over the rp les (Burns et al. 1979), as well as collisions. Dust produc- stellar spectrum, was calculated as a function of mirror size sfrom Boston n in the outer region and dust transport through the in- (Burns et al. 1979; Gustafson 1994). We then computed the Micromachines is mediate region are modeled with a statistical collisional radiation pressure to gravity ratio, β (Fig. 2). The resulting prepared for de. To study the dust in the inner region, we need to han- β(s) was utilized to compute the direct radiation being pressure e dust interactions with the inner planet. These cannot and Poynting-Robertson forces. integration. treated by the collisional code, so we model the inner The figure at right gion by collisionless numerical integration. shows the 2.5. Stellar wind expected flattened The stellar wind was included by a factor β /β, which is sw 2. Stellar properties surface figure. the ratio of stellar wind pressure to radiation pressure: SiC mirror, ⋆ = 0.83M⊙ e assumed Example a stellar20”mass of M New primary mirror undergoing initial figuring. βsw Fsw Ṁ⋆ vsw c Qsw enedicthttp://www.northropgrumman.com. et al. 2006) and a luminosity of L⋆ = 0.32L⊙ = = , (1) i Folco et al. 2007). For the stellar spectrum we used a β Frp L⋆ Qrp xtGen model (Hauschildt et al. 1999) with an effective mperature of 5200 K, log g = 4.5, solar metallicity, and where Qsw is the efficiency factor for stellar wind pressure 70 seconds after launch. Simulated ϵEri observations 7. FLIGHT, ANOMALY, RE after subtraction ofPICTURE dustless Rigelfrom PSFWhite Sands Missile Ran launched Simulation Inputs: Inner Warm Ring 10 Observing Time Interfering the PICTURE wavefronts: Outer Warm Ring ) e r ( <1 0 A U TARGET Nuller performance is simulated by interfering the complex wavefronts of the sheared nuller arms and generating the resultant point-spread-function (PSF) for a list of discrete points, composed of the central star and the warm inner ring, with POPPY (Physical Optics Propagation with PYthon) 70% ice + 30% astrosil 50% ice + 50% astrosil [Perrin et al 2012, github.com/mperrin/poppy]. We computed the polychromatic PSFs in parallel 100% astrosil using PiCloud.com, which after stacking and addition of noise, produce realistic images. blow-out limit -2 inn Visible Nulling Coronagraph, 600-750 nm, shear of 0.15m Nuller 10 planet 'B' 0.5 m, f/12.3 Gregorian Telescope ! 0 β-ratio ou te r excess flux [Jy] 2 an pl Observing Plan Mission Properties The PICTURE (Planetary Imaging Concept Testbed Using a Rocket Experiment) sounding No.interferometer 2, 2009 EPSILON the ERIDANI DEBRIS DISK rocket will demonstrate a nulling (a “nuller”) to characterize exozodiacal dust disk of Epsilon Eridani (K2V, 3.22 pc) in reflected visible light to an inner radius of 1.5 AU (0.5”) from the surface of the star. The first launch of PICTURE suffered a telemetry failure and the primary mirror was shattered upon landing. A new launch is scheduled and the PICTURE payload is currently undergoing refurbishment, including receiving a new SiC primary mirror. PICTURE visible light observations will constrain scattering properties of the Epsilon Eridani exozodiacal dust and debris environment. Measuring the dust brightness of the system constraints the background which must be overcome for future exoplanet observations. Additionally, PICTURE will demonstrate operation of a MEMS deformable mirror and a visible nulling coronagraph in space. Improved modeling and post-flight measurement of instrument performance allow us to present refined exozodiacal dust sensitivities. Future prospects look towards a PICTURE refligh and technology goals of the first mission. In addition, flight. A number of hardware upgrades have been iden contributors to OPD in the nuller, the telescope pri rigid SiC primary would narrow the void between labo performance in both environments with a similar are available from BMC. A drop-in replacement could be electronics. The nuller calibration system could also that does not obscure the calibration reference beam. avenue for data post-processing. Acknowledgements: (Mendillo et al. 2012b) PICTURE is funded by the National Aeronautics and Space Administration, Proc. of SPIE V Grant NNX13AD50G. Boston Micromachines Corporation provided DM surface Downloaded From: http://proceedings.spiedigitallibrary.org/ on 12/14/2012 Terms o measurement data used for this work. Thanks to D. Hammerle and T. Bruno at AOA Xinetics for their help and assistance in refurbishing the PICTURE telescope. References: Backman, D., M., et al. 2009..ApJ 690,2. Bailey, V., et al. 2013. ApJ 767, 31. Mendillo, C. B et al. 2012a. Applied Optics 51, 29. Mendillo, C. B., et al. 2012b. In Proc. SPIE, 84420E–84420E. Perrin, et al. 2012. In Proc. SPIE, 8442:84423D–84423D–11. Pickles, A. J. 1998. PASP, 110, 749. Reidemeister, et al. 2011. Astronomy & Astrophysics 527, A57. ! Printing Instructions Completing Your Poster Design! ! 1. 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