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Circumstellar Environments

Circumstellar Environments. The Team. Historical Group (from IRA-Noto): G.Umana, C.S. Buemi INAF-OACt C. Trigilio INAF-OACt and Università di Catania P. Leto INAF-IRA, Noto. PhD students: L. Cerrigone, CfA-Università di Catania

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Circumstellar Environments

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  1. Circumstellar Environments

  2. The Team Historical Group (from IRA-Noto): G.Umana, C.S. Buemi INAF-OACt C. Trigilio INAF-OACt and Università di Catania P. Leto INAF-IRA, Noto PhD students: L. Cerrigone, CfA-Università di Catania S. Dolei, P. Manzitto, C. Siringo Università di Catania Collaborators: F. Leone, Università di Catania J. Hora, G. Fazio, M. Marengo SAO-CfA C. Burigana INAF-IASF H. Olofsson OSO, G. Giardino (ESA), R. Paladini (JPL)

  3. The project The study of circumstellar environments by means of radio observations • Radio techniques very useful in multi-frequency approaches • Unique for some classes of Galactic objects • Circumstellar environments: • Coronae around active stellar systems • Stellar Magnetosphere • Stellar ejecta, late stage of stellar evolution

  4. The project Funds (since 2004): Besides normal (small) INAF science funding….

  5. Radio Emission from CP stars • Anomalous abundances • Strong (>3000 G) dipolar magnetic field • Variability (continuum, lines, B) • - Oblique Rotator Model radio Explained in terms of oblique rotator model Radio emission (also variable ) consistent with Gyrosynchrotron plus a coherent component

  6. Radio Emission from CP stars Goal Understanding the origin of variable radio emission from CP Method By modeling the radio flux density light-curve VLA and ATCA project (multi-frequency, multi-configuration) Principal Results: • Full coverage of radio curve at different frequency for • 3 stars • Development of a 3D code to reconstruct the • magnetosphere of CP and modeling of radio light curve • Discovery of a new component in the radio emission • Use of coherent emission as a period marker

  7. The 3D code for radio emission -Gyrosynchrotron from the magnetosphere 18 cm, 4 cm, 1 cm Good agreement with observations Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F., 2004 Leto P., Trigilio, C., Buemi, C. Umana, G., Leone, F. ,2006

  8. CU Vir: the coherent radio component Discovery of a new component of radio emission: • occurring only at particular rotational phases • 100% circularly polarized • highly directive • persistent over years Consistent with Cyclotron Maser Emission

  9. CU Vir: the coherent radio component Consistent with Cyclotron Maser Emission • occurring only at particular rotational • phases • persistent over years Marker of the rotational period CU Virginis is slowing down dP/dt ~ 10-9 s yr-1 Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F., 2008

  10. Stellar Ejecta Observed around stellar objects in late evolutionary phases: -AGB PNe Mass-loss  CSE -LBV • Open questions: • Shaping: mass-loss (asymmetric) or evolution in an asymmetric • environment? • Mass and T (gas & dust content) • Multiple components (different mass-loss episodes?) • Chemistry and its evolution with time (photodissociation, shocks) • Chemical evolution of Galaxy (processed material return to ISM) • Ideal laboratory to study wind/shocks interaction with ISM

  11. O B A F G K M MMS 1 -8 Mo Stellar Ejecta: AGB PNe 104 L 102 L 1 L 10-2 L 10-4 L yrs ~800 ~1000 UV * Visible IR IR-farIR IR-radio

  12. Hunting for Young PNe Goal Understanding the shaping of PNe, through observation of YPNe where the shaping mechanism is still active Method Select a sample of TO (AGBPNe) objects; Detect radio to find YPNe • far-IR characteristics (excess) • Optical characteristics • B spectral type • spectral and photometric variability -The onset of ionization can be marked by the presence of free-free emission… VLA and ATCA project (multi-frequency, multi-configuration) 42 objects Principal Results: • Detected 17 sources; Established their evolutionary status (YPNe) • Other 25 objects are genuine hot post-AGB stars. • Radio spectra consistent with a PN in the early stage of its • evolution • High-resolution mapping Bi-polar morphology

  13. YPNe: sub-arc observations Radio morphology: bi-polar shaping is already active! VLA-A, 3.6cm 1 Cerrigone,L., Umana, G., trigilio, C., Buemi, C., Leto, P. ., 2008

  14. IRAS 22568+6141 Umana, G., Trigilio, C., Cerrigone, L., Buemi, C., Leto, P., 2008 VLA-A, 3.6cm VLA-C, 3.6cm 1 Total flux= 32mJy Central component 1.65 0.05 mJy Consistent with stellar wind? (Mass-loss) new VLA, high resolution, multi-frequency data already available (AU119), waiting for reduction! H-alpha

  15. CSE: the dust component Goal Understanding the dust contribution to the shaping Method Inspecting the dust properties of envelope in TO (AGBPNe) objects: -systematic differences between radio detected (YPNe) and post-AGB? SST project on YPNe, part of the SST-GTO on Stellar ejecta (PI G. Fazio) IRAC + IRS observations of 42 TO (with radio infos) Principal Results: • CSE around TO generally very compact (not resolved by IRAC) • IRS spectra dominated by thermal dust emission plus spectral • structures due to dust (crystalline silicates) • besides recombination lines, no evident differences between radio (YPNe) • and not radio detected (hot post-AGB) objects. • about 50% of the sample shows mixed chemistry • necessity to introduce big grains to fit SEDs

  16. Silicates [NeII] [ArII] PAH PAH Silicates The dust component: Results When SED (up to mm) are modeled: - necessity to consider multi-component CSE - big grains (0.05-100 m) - IRS spectra dominated by thermal dust emission plus spectral structures due to crystalline silicates - part of the sample shows mixed chemistry: not consistent with evolution theory -Consistent with a reservoir of O-rich material, probably an equatorial disk (PPNe Red Rectangle)  strong clue for stellar ejecta being collimated by such structures! Cerrigone, L., Hora, J., Umana, G., Trigilio, C., 2007 Cerrigone, L., PhD Thesis, 2008

  17. MMS > 25 Mo Stellar Ejecta: LBV • log L/L ~ 5.0-6.3 • strong mass-loss ~ 10-6÷10-4 Myr-1 • Variability • Outbursts ΔV ~ 1-2 mag

  18. LBVs: the ionized gas Understanding the LBV phenomenon through the study of their ejecta (morphology and physics of the nebula) Goal Determine the properties of the radio emission, tracing the ionized gas component of the ejecta -Symmetric versus Asymmetric morphology - Mass-loss of the central objects (current-day mass-loss) Method VLA Multi-frequency, multi-configuration project Principal Results: • Radio morphologies in general asymmetric and structured • High-resolution allows to resolve the core component • High-resolution, multi-frequency allows to determine mass-loss • Radio observations more efficient than usual H (no extinction) • essential to probe the ionized component in strongly reddened object

  19. IRAS 18576+0341 LBVs in Radio Probing the ionized component in a very dusty environment Strongly reddened object: no optical counterpart VLA-A, C-band -Multi-frequency, high resolution VLA observations: -a core component (LBV’s wind) -an extended, asymmetric nebula Current day mass-loss 3.7 10-5Myr-1 B0-B0.5 I, Teff ~ 2.6 104 K Umana, G., Buemi, C.S., Trigilio, C. , Leto, P. et al., 2005

  20. LBVs: the dust component Understanding the LBV phenomenon through the study of their ejecta (morphology and physics of the nebula) Goal Determine the properties of the mid-IR emission, tracing the dust component of the ejecta -Symmetric versus Asymmetric morphology - Comparison with ionized gas component to derive clues for shaping Method VISIR@VLT project multi-frequency sub-arcsec imaging Principal Results: • Ejecta morphologies: highly structured • Thermal dust morphologies DIFFERENT from radio.

  21. 11.26 m 12.27 m 17.65 m IRAS 18576+0341 Mapping with VISIR@VLTpixel scale 0.075 IRS@SST

  22. IRAS 18576+0341 Comparison between ionized gas and dust: sub-arcsec mapping 4 VLA-A, 5 GHz (6cm) VISIR 12.25 m -4 Clues on mass-loss and shaping: A) Mass-loss can occur asymmetrically; outflows may be shaped by dusty structures B) dust distribution not homogeneous dust competes with gas in absorbing UV radiation: holes in dust allow gas to glow!

  23. LBVs: ionized gas and dust comparison VLA-A 3.6cm VISIR 12.25 m Different situation in HD168625 - The ionized gas appears contained by dust: - Outflow channeled by a dusty equatorial torus?? kinematical information necessary!

  24. LBV: more on the dust component Goal Determine the characteristics of dust component: yield to ISM Chemistry; mass-loss history Method Determine mid-IR spectral and morphological properties Modeling the SEDs (CLOUDY)  Mass-loss history -SST project on Galactic LBVs, part of the SST-GTO on Stellar ejecta (PI G. Fazio) IRAC+IRS (low + high res) of nine Galactic LBV -SAGE Collaboration on LBVs in MCs (IRAC+IRS+MIPS) First Results: • Dusty CSE around Galactic LBV can be very extended • Both regular (spherical) and asymmetric morphology observed. • IRS spectra: dominated by emission lines and dust spectral features (PAHs) • [Fe II] mid-IR lines detected: possible diagnostics for shocks

  25. Stellar ejecta Wray17-96 SST-IRAC mosaic IRAC LBV GTO program

  26. Stellar ejecta: the future In the next years new instrumentations will come on-line ALMA: mm interferometer ( 30-900 GHz) spectral and continuum capabilities (sub-mJy) , sub-arcsec imaging 2011 EVLA: cm interferometer (1.4-50 GHz) : spectral and continuum capabilities (sub-mJy) , sub-arcsec imaging 2009

  27. Stellar ejecta:the future Stellar ejecta possible foregrounds for CMB: - from a feasibility study ~400 CSE will be detected by PLANCK (Umana, G. Burigana, C., Trigilio, C.- 2006) - PLANCK will provide flux measurements, between 30 and 900 GHz, for the radio brightest PNe SEDs Umana, Leto, Trigilio, Buemi, Toscano, Manzitto, Dolei, Cerrigone, 2008 (based on 43 GHz single dish INAF-IRA teleacope Obs) PLANCK mission, full sky coverage (30 to 900 GHz)-end 2008

  28. Stellar ejecta:ALMA • ALMA will provide detailed (sub-arcsec, sub-mJy) maps of: • ionized gas continuum (30 GHz…..) morphology • molecular gas CO (100 GHz) morphology (Kinematic) • dust continuum (100 GHz…) morphology Morphological and spectral studies of different components coexisting in the ejecta  CLUES on shaping ionized gas continuum continuum (1.4-50 GHz) RRLs (1.4-50 GHz) molecular gasCO H2 (near-IR) Dust continuum continuum (mid-IR) SYNERGIES ALMA(sub-arc, sub-mJy) VISIR@VLT (sub-arc, mJy) HST (sub-arc) EVLA (sub-arc, sub-mJy)

  29. ALMA-2011+…… putting together the pieces Radio jet that makes its way through the CO cocoon Dusty disk/torus Molecular Cocoon

  30. Stellar ejecta:ALMA mm and submm observations provide strong constraints for SED modeling Post-AGB stars mm obs MAMBO@Iram 30m + SEDs modeling (DUSTY):  = 0.9-1.6 R =1016 10 17 cm dM/dt~ 10-6-10-5 ALMA: Detailed maps of CSE dimension, structure… VERY strong constraints to the SED Modeling! Buemi, C, Umana, G., Leto,P., Trigilio, C 2007

  31. The link to the Catania University Radioastronomy (C. Trigilio) Undergraduate course (Physics) Galactic Radiosources (G. Umana) Lectures for PhD program All the students trained at INAF-IRA 32m Radiotelescope: acquisition techniques, data reductions ….. PhD students: L. Cerrigone, Infrared and Radio properties of YPNe CfA-Università di Catania Thesis defence next February P. Manzitto, SEDs modeling of PNe Università di Catania, III year C. Siringo,SiO maser in CSE Università di Catania, begin III year S. Dolei, Radio modeling of PNe Università di Catania, begin II year Science for ALMA Science for ALMA PLANCK, HERSCHEL Science for ALMA Science for ALMA PLANCK, HERSCHEL

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