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Visiting Committee Catania, 17 dicembre 2007 G. Umana Circumstellar Environments.

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Presentation on theme: "Visiting Committee Catania, 17 dicembre 2007 G. Umana Circumstellar Environments."— Presentation transcript:

1 Visiting Committee Catania, 17 dicembre 2007 G. Umana Circumstellar Environments

2 Visiting Committee Catania, 17 dicembre 2007 G. Umana 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 Visiting Committee Catania, 17 dicembre 2007 G. Umana 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 Visiting Committee Catania, 17 dicembre 2007 G. Umana The project Funds (since 2004): Besides normal (small) INAF science funding… ASI-Planck Science 18 k ASI-Planck Science 7.5 k INAF/Alma6.2 k

5 Visiting Committee Catania, 17 dicembre 2007 G. Umana Radio Emission from CP stars Anomalous abundances Strong (>3000 G) dipolar magnetic field Variability (continuum, lines, B) - Oblique Rotator Model Explained in terms of oblique rotator model Radio emission (also variable ) consistent with Gyrosynchrotron plus a coherent component radio

6 Visiting Committee Catania, 17 dicembre 2007 G. Umana 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: o Full coverage of radio curve at different frequency for 3 stars o Development of a 3D code to reconstruct the magnetosphere of CP and modeling of radio light curve o Discovery of a new component in the radio emission o Use of coherent emission as a period marker Radio Emission from CP stars

7 Visiting Committee Catania, 17 dicembre 2007 G. Umana 18 cm, 4 cm, 1 cm -Gyrosynchrotron from the magnetosphere The 3D code for radio emission Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F., 2004 Leto P., Trigilio, C., Buemi, C. Umana, G., Leone, F.,2006 Good agreement with observations

8 Visiting Committee Catania, 17 dicembre 2007 G. Umana Discovery of a new component of radio emission: CU Vir: the coherent radio component occurring only at particular rotational phases 100% circularly polarized highly directive persistent over years Consistent with Cyclotron Maser Emission

9 Visiting Committee Catania, 17 dicembre 2007 G. Umana Marker of the rotational period Consistent with Cyclotron Maser Emission occurring only at particular rotational phases persistent over years CU Virginis is slowing down dP/dt ~ s yr -1 Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F., 2008 CU Vir: the coherent radio component

10 Visiting Committee Catania, 17 dicembre 2007 G. Umana Stellar Ejecta Observed around stellar objects in late evolutionary phases: - AGB PNe Mass-loss CSE -LBV Open questions : o Shaping: mass-loss (asymmetric) or evolution in an asymmetric environment? o Mass and T (gas & dust content) o Multiple components (different mass-loss episodes?) o Chemistry and its evolution with time (photodissociation, shocks) o Chemical evolution of Galaxy (processed material return to ISM) o Ideal laboratory to study wind/shocks interaction with ISM

11 Visiting Committee Catania, 17 dicembre 2007 G. Umana O B A F G K M 10 4 L 10 2 L 1 L L L M MS 1 -8 Mo Stellar Ejecta: AGB PNe ~800 ~1000 yrs * Visible UV IR IR-farIR IR-radio

12 Visiting Committee Catania, 17 dicembre 2007 G. Umana 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 VLA and ATCA project (multi-frequency, multi-configuration) 42 objects Principal Results: o Detected 17 sources; Established their evolutionary status (YPNe) o Other 25 objects are genuine hot post-AGB stars. o Radio spectra consistent with a PN in the early stage of its evolution o High-resolution mapping Bi-polar morphology Hunting for Young PNe 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…

13 Visiting Committee Catania, 17 dicembre 2007 G. Umana YPNe: sub-arc observations VLA-A, 3.6cm 1 Radio morphology: bi-polar shaping is already active! Cerrigone,L., Umana, G., trigilio, C., Buemi, C., Leto, P.., 2008

14 Visiting Committee Catania, 17 dicembre 2007 G. Umana H-alpha IRAS VLA-C, 3.6cm VLA-A, 3.6cm Total flux= 32mJy Central component mJy Consistent with stellar wind? (Mass-loss) new VLA, high resolution, multi-frequency data already available (AU119), waiting for reduction! 1 Umana, G., Trigilio, C., Cerrigone, L., Buemi, C., Leto, P., 2008

15 Visiting Committee Catania, 17 dicembre 2007 G. Umana 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: o CSE around TO generally very compact (not resolved by IRAC) o IRS spectra dominated by thermal dust emission plus spectral structures due to dust (crystalline silicates) o besides recombination lines, no evident differences between radio (YPNe) and not radio detected (hot post-AGB) objects. o about 50% of the sample shows mixed chemistry o necessity to introduce big grains to fit SEDs

16 Visiting Committee Catania, 17 dicembre 2007 G. Umana The dust component: Results - 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 Silicates Cerrigone, L., Hora, J., Umana, G., Trigilio, C., 2007 Cerrigone, L., PhD Thesis, 2008 [ArII] [NeII] PAH Silicates When SED (up to mm) are modeled: - necessity to consider multi-component CSE - big grains ( m) - 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!

17 Visiting Committee Catania, 17 dicembre 2007 G. Umana Stellar Ejecta: LBV log L/L ~ strong mass-loss ~ ÷10 -4 M yr -1 Variability Outbursts ΔV ~ 1-2 mag M MS > 25 Mo

18 Visiting Committee Catania, 17 dicembre 2007 G. Umana LBVs: the ionized gas Goal Understanding the LBV phenomenon through the study of their ejecta (morphology and physics of the nebula) Method 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) VLA Multi-frequency, multi-configuration project Principal Results: o Radio morphologies in general asymmetric and structured o High-resolution allows to resolve the core component o High-resolution, multi-frequency allows to determine mass-loss o Radio observations more efficient than usual H (no extinction) essential to probe the ionized component in strongly reddened object

19 Visiting Committee Catania, 17 dicembre 2007 G. Umana LBVs in Radio Probing the ionized component in a very dusty environment Umana, G., Buemi, C.S., Trigilio, C., Leto, P. et al., 2005 IRAS Strongly reddened object: no optical counterpart VLA-A, C-band -Multi-frequency, high resolution VLA observations: -a core component (LBVs wind) -an extended, asymmetric nebula Current day mass-loss M yr -1 B0-B0.5 I, T eff ~ K

20 Visiting Committee Catania, 17 dicembre 2007 G. Umana LBVs: the dust component Goal Understanding the LBV phenomenon through the study of their ejecta (morphology and physics of the nebula) Method 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 project multi-frequency sub-arcsec imaging Principal Results: o Ejecta morphologies: highly structured o Thermal dust morphologies DIFFERENT from radio.

21 Visiting Committee Catania, 17 dicembre 2007 G. Umana Mapping with pixel scale m m m IRAS

22 Visiting Committee Catania, 17 dicembre 2007 G. Umana Comparison between ionized gas and dust: sub-arcsec mapping IRAS VLA-A, 5 GHz (6cm) VISIR m 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 Visiting Committee Catania, 17 dicembre 2007 G. Umana LBVs: ionized gas and dust comparison Different situation in HD The ionized gas appears contained by dust: - Outflow channeled by a dusty equatorial torus?? kinematical information necessary! VISIR m VLA-A 3.6cm

24 Visiting Committee Catania, 17 dicembre 2007 G. Umana 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: o Dusty CSE around Galactic LBV can be very extended o Both regular (spherical) and asymmetric morphology observed. o IRS spectra: dominated by emission lines and dust spectral features (PAHs) o [Fe II] mid-IR lines detected: possible diagnostics for shocks

25 Visiting Committee Catania, 17 dicembre 2007 G. Umana Stellar ejecta Wray17-96 SST-IRAC mosaic IRAC LBV GTO program

26 Visiting Committee Catania, 17 dicembre 2007 G. Umana In the next years new instrumentations will come on-line ALMA: mm interferometer ( GHz) spectral and continuum capabilities (sub-mJy), sub-arcsec imaging 2011 EVLA: cm interferometer ( GHz) : spectral and continuum capabilities (sub-mJy), sub-arcsec imaging 2009 Stellar ejecta: the future

27 Visiting Committee Catania, 17 dicembre 2007 G. Umana Stellar ejecta possible foregrounds for CMB: - from a feasibility study ~400 CSE will be detected by PLANCK ( Umana, G. Burigana, C., Trigilio, C ) - 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 Stellar ejecta:the future

28 Visiting Committee Catania, 17 dicembre 2007 G. Umana 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 ALMA (sub-arc, sub-mJy) (sub-arc, mJy) HST (sub-arc) EVLA (sub-arc, sub-mJy) SYNERGIES ionized gas continuum continuum ( GHz) RRLs ( GHz) molecular gas CO H2 (near-IR) Dust continuum continuum (mid-IR)

29 Visiting Committee Catania, 17 dicembre 2007 G. Umana ALMA-2011+…… putting together the pieces Radio jet that makes its way through the CO cocoon Dusty disk/torus Molecular Cocoon

30 Visiting Committee Catania, 17 dicembre 2007 G. Umana mm and submm observations provide strong constraints for SED modeling Post-AGB stars mm obs 30m + SEDs modeling (DUSTY): = R = cm dM/dt~ Stellar ejecta:ALMA Buemi, C, Umana, G., Leto,P., Trigilio, C 2007 ALMA: Detailed maps of CSE dimension, structure… VERY strong constraints to the SED Modeling!

31 Visiting Committee Catania, 17 dicembre 2007 G. Umana The link to the Catania University Radioastronomy (C. Trigilio) Undergraduate course (Physics) Galactic Radiosources (G. Umana) Lectures for PhD program 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 All the students trained at INAF-IRA 32m Radiotelescope: acquisition techniques, data reductions ….. Science for ALMA PLANCK, HERSCHEL Science for ALMA PLANCK, HERSCHEL


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