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Tracing Protostellar Evolution by Observations of Ices

Tracing Protostellar Evolution by Observations of Ices. Adwin Boogert Geoff Blake Michiel Hogerheijde. Caltech/OVRO Caltech/OVRO Univ. of Arizona. Topics. Introduction: a grain in space The technique: ice processing massive protostars Ices toward low mass protostars

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Tracing Protostellar Evolution by Observations of Ices

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  1. Tracing Protostellar Evolution by Observations of Ices Adwin Boogert Geoff Blake Michiel Hogerheijde Caltech/OVRO Caltech/OVRO Univ. of Arizona

  2. Topics • Introduction: a grain in space • The technique: ice processing massive protostars • Ices toward low mass protostars • Ice location along line of sight • CO ices in an edge on disk • Processing of CO ices • Detection of 13CO isotope in ices • Conclusions and future work

  3. Ice processing massive protostars Solid 13CO2: Evidence envelope heating: • CO2 crystallization (Boogert et al. 2000; Gerakines et al. 1999) • H2O crystallization (Smith et al. 1989) • gas/solid ratio increases (van Dishoeck et al. 1997) • Detailed modelling gas phase mm-wave observations (van der Tak et al. 2000)

  4. Ice processing massive protostars Solid 13CO2: Evidence envelope heating: • CO2 crystallization (Boogert et al. 2000; Gerakines et al. 1999) • H2O crystallization (Smith et al. 1989) • gas/solid ratio increases (van Dishoeck et al. 1997) • Detailed modelling gas phase mm-wave observations (van der Tak et al. 2000)

  5. Ices in low mass YSOs • Ices abundant toward Elias 29: most luminous (30 Lsun) low mass (1-2 Msun) protostar in r Oph cloud • Before drawing conclusions on ice processing, one needs to locate ices along line of sight • With this goal, Elias 29 was studied in gas phase emission lines

  6. Low mass YSOs: where are the ices? • Line of sight Elias 29 is complex! (Boogert, Hogerheijde, Ceccarelli, et al., ApJ 570,708, 2002)

  7. Low mass YSOs: where are the ices? • Line of sight Elias 29 is complex! • Face on disk located behind large column (AV=20) of cool (T< 40 K) foreground material which may well harbor the unprocessed ices. (Boogert, Hogerheijde, Ceccarelli, et al., ApJ 570,708, 2002)

  8. Low mass YSOs: ices in disks! HCO+ 3-2 OVRO: • OVRO spectra low mass protostar L1489 IRS show large 2000 AU radius close to edge-on disk, in almost Keplerian rotation with an infall component (Hogerheijde, ApJ 553, 618, 2001) • 4.7 mm Keck/NIRSPEC CO spectra confirm edge-on infalling nature of disk and confine temperature and density structure (Boogert et al., ApJ 568,761, 2002). • How about the ices? CO Keck/NIRSPEC:

  9. Ices in disk L1489 IRS • Prominent band of solid CO detected toward L1489, originating in large, flaring disk. • CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

  10. Ices in disk L1489 IRS • Prominent band of solid CO detected toward L1489, originating in large, flaring disk. • CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: • 'polar' H2O:CO (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

  11. Ices in disk L1489 IRS • Prominent band of solid CO detected toward L1489, originating in large, flaring disk. • CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: • 'polar' H2O:CO • 'apolar' CO2:CO [NEW!] (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

  12. Ices in disk L1489 IRS • Prominent band of solid CO detected toward L1489, originating in large, flaring disk. • CO band consists of 3 components, explained by laboratory simulations as originating from CO in 3 distinct mixtures: • 'polar' H2O:CO • 'apolar' CO2:CO [NEW!] • 'apolar' pure CO (Boogert, Hogerheijde & Blake, ApJ 568,761, 2002)

  13. Ice processing in disk • Are ices in L1489 IRS disk processed?

  14. Ice processing in disk • Are ices in L1489 IRS disk processed? • Empirical answer by comparing CO ice band with established unprocessed line of sight, NGC 7538 : IRS9: • apolar CO-rich ices evaporated in L1489 IRS disk • abundance CO2 and H2O containing CO ices unchanged • no evidence CO2 formation by energetic processing • Larger sample needs to be studied! • See also poster Pontoppidan et al. (Boogert, Blake & Tielens, ApJ 577n1, in press)

  15. Ice processing in disk • Are ices in L1489 IRS disk processed? • Empirical answer by comparing CO ice band with established unprocessed line of sight, NGC 7538 : IRS9: • apolar CO-rich ices evaporated in L1489 IRS disk • abundance CO2 and H2O containing CO ices unchanged • no evidence CO2 formation by energetic processing • Larger sample needs to be studied! • See also poster Pontoppidan et al. (Boogert, Blake & Tielens, ApJ 577n1, in press)

  16. Detection of solid 13CO:new clues to nature of apolar ices • First detection of solid 13CO • High spectral resolution required! NGC 7538 : IRS9: (Boogert, Blake & Tielens, ApJ 577n1, in press)

  17. Detection of solid 13CO:new clues to nature of apolar ices • First detection of solid 13CO • High spectral resolution required! • New insights into nature apolar ices: • 13CO well fitted with pure CO, but 12CO..... NGC 7538 : IRS9: (Boogert, Blake & Tielens, ApJ 577n1, in press)

  18. Detection of solid 13CO:new clues to nature of apolar ices • First detection of solid 13CO • High spectral resolution required! • New insights into nature apolar ices: • 13CO well fitted with pure CO, but 12CO..... • ...requires ellipsoidal grains NGC 7538 : IRS9: (Boogert, Blake & Tielens, ApJ 577n1, in press)

  19. Detection of solid 13CO:new clues to nature of apolar ices • First detection of solid 13CO • High spectral resolution required! • New insights into nature apolar ices: • 13CO well fitted with pure CO, but 12CO..... • ...requires ellipsoidal grains • CO and CO2 not mixed • Finally: isotope ratios NGC 7538 : IRS9: (Boogert, Blake & Tielens, ApJ 577n1, in press)

  20. Conclusions/Future Work • Comprehensive picture of ices as tracer of evolution of massive YSOs • Infrared observations of ices and (sub-)mm observations of gas need to be combined to determine physical conditions and location of ices • Ices detected in disks of low mass YSOs. Warm upper layers of L1489 disk show evaporation of apolar ices. No signs energetic processing found. • 13CO isotope new tracer of ices • Promising start, but thorough study of large sample of objects both in gas and solid state needed to answer questions on origin and evolution of solar system ices.

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